seattle dpd - 2012 seattle building code, chapter 21 …pan/documents/web_informational/...masonry...

2012 SEATTLE BUILDING CODE 489

CHAPTER 21

MASONRY

SECTION 2101GENERAL

2101.1 Scope. This chapter shall govern the materials,design, construction and quality of masonry.

2101.2 Design methods. Masonry shall comply with the pro-visions of one of the following design methods in this chapteras well as the requirements of Sections 2101 through 2104.Masonry designed by the allowable stress design provisionsof Section 2101.2.1, the strength design provisions of Section2101.2.2, the prestressed masonry provisions of Section2101.2.3, or the direct design requirements of Section2101.2.7 shall comply with Section 2105.

2101.2.1 Allowable stress design. Masonry designed bythe allowable stress design method shall comply with theprovisions of Sections 2106 and 2107.

2101.2.2 Strength design. Masonry designed by thestrength design method shall comply with the provisionsof Sections 2106 and 2108, except that autoclaved aeratedconcrete (AAC) masonry shall comply with the provisionsof Section 2106 and Chapters 1 and 8 of TMS 402/ACI530/ASCE 5.

2101.2.3 Prestressed masonry. Prestressed masonry shallbe designed in accordance with Chapters 1 and 4 of TMS402/ACI 530/ASCE 5 and Section 2106. Special inspec-tion during construction shall be provided as set forth inSection 1705.4.

2101.2.4 Empirical design. Masonry designed by theempirical design method shall comply with the provisionsof Sections 2106 and 2109 or Chapter 5 of TMS 402/ACI530/ASCE 5.

2101.2.5 Glass unit masonry. Glass unit masonry shallcomply with the provisions of Section 2110 or Chapter 7of TMS 402/ACI 530/ASCE 5.

2101.2.6 Masonry veneer. Masonry veneer shall complywith the provisions of Chapter 14 or Chapter 6 of TMS402/ACI 530/ASCE 5.

2101.2.7 Direct design. Masonry designed by the directdesign method shall comply with the provisions of TMS403.

2101.3 Construction documents. The construction docu-ments shall show all of the items required by this code includ-ing the following:

1. Specified size, grade, type and location of reinforce-ment, anchors and wall ties.

2. Reinforcing bars to be welded and welding procedure.

3. Size and location of structural elements.

4. Provisions for dimensional changes resulting from elas-tic deformation, creep, shrinkage, temperature andmoisture.

5. Loads used in the design of masonry.

6. Specified compressive strength of masonry at statedages or stages of construction for which masonry isdesigned, except where specifically exempted by thiscode.

7. Details of anchorage of masonry to structural members,frames and other construction, including the type, sizeand location of connectors.

8. Size and permitted location of conduits, pipes andsleeves.

9. The minimum level of testing and inspection as definedin Chapter 17, or an itemized testing and inspectionprogram that meets or exceeds the requirements ofChapter 17.

2101.3.1 Fireplace drawings. The construction docu-ments shall describe in sufficient detail the location, sizeand construction of masonry fireplaces. The thickness andcharacteristics of materials and the clearances from walls,partitions and ceilings shall be indicated.

SECTION 2102DEFINITIONS AND NOTATIONS

2102.1 General. The following terms are defined in Chapter2:

AAC MASONRY.

ADOBE CONSTRUCTION.

Adobe, stabilized.

Adobe, unstabilized.

ANCHOR.

ARCHITECTURAL TERRA COTTA.

AREA.

Gross cross-sectional.

Net cross-sectional.

AUTOCLAVED AERATED CONCRETE (AAC).

BED JOINT.

BOND BEAM.

BRICK.

Calcium silicate (sand lime brick).

Clay or shale.

Concrete.

CAST STONE.

CELL.

CHIMNEY.

21_Seattle_Build_2012.fm Page 489 Wednesday, November 13, 2013 8:54 AM

MASONRY

490 2012 SEATTLE BUILDING CODE

CHIMNEY TYPES.

High-heat appliance type.

Low-heat appliance type.

Masonry type.

Medium-heat appliance type.

CLEANOUT.

COLLAR JOINT.

COMPRESSIVE STRENGTH OF MASONRY.

DIMENSIONS.

Nominal.

Specified.

FIREPLACE.

FIREPLACE THROAT.

FOUNDATION PIER.

HEAD JOINT.

MASONRY.

Ashlar masonry.

Coursed ashlar.

Glass unit masonry.

Plain masonry.

Random ashlar.

Reinforced masonry.

Solid masonry.

Unreinforced (plain) masonry.

MASONRY UNIT.

Hollow.

Solid.

MORTAR.

MORTAR, SURFACE-BONDING.

PRESTRESSED MASONRY.

PRISM.

RUBBLE MASONRY.

Coursed rubble.

Random rubble.

Rough or ordinary rubble.

RUNNING BOND.

SHEAR WALL.

Detailed plain masonry shear wall.

Intermediate prestressed masonry shear wall.

Intermediate reinforced masonry shear wall.

Ordinary plain masonry shear wall.

Ordinary plain prestressed masonry shear wall.

Ordinary reinforced masonry shear wall.

Special prestressed masonry shear wall.

Special reinforced masonry shear wall.

SPECIFIED.

SPECIFIED COMPRESSIVE STRENGTH OFMASONRY, f ′m.

STACK BOND.

STONE MASONRY.

Ashlar stone masonry.

Rubble stone masonry.

STRENGTH.

Design strength.

Nominal strength.

Required strength.

THIN-BED MORTAR.

TIE, WALL.

TILE, STRUCTURAL CLAY.

WALL.

Cavity wall.

Composite wall.

Dry-stacked, surface-bonded wall.

Masonry-bonded hollow wall.

Parapet wall.

WYTHE.

NOTATIONS.

db = Diameter of reinforcement, inches (mm).

Fs = Allowable tensile or compressive stress inreinforcement, psi (MPa).

fr = Modulus of rupture, psi (MPa).

f ′AAC = Specified compressive strength of AAC masonry, theminimum compressive strength for a class of AACmasonry as specified in ASTM C 1386, psi (MPa).

f ′m = Specified compressive strength of masonry at age of28 days, psi (MPa).

f ′mi = Specified compressive strength of masonry at thetime of prestress transfer, psi (MPa).

K = The lesser of the masonry cover, clear spacingbetween adjacent reinforcement, or five times db,inches (mm).

Ls = Distance between supports, inches (mm).

ld = Required development length or lap length ofreinforcement, inches (mm).

P = The applied load at failure, pounds (N).

St = Thickness of the test specimen measured parallel tothe direction of load, inches (mm).

Sw = Width of the test specimen measured parallel to theloading cylinder, inches (mm).


MASONRY


SECTION 2103MASONRY CONSTRUCTION MATERIALS

2103.1 Concrete masonry units. Concrete masonry unitsshall conform to the following standards: ASTM C 55 forconcrete brick; ASTM C 73 for calcium silicate face brick;ASTM C 90 for load-bearing concrete masonry units orASTM C 744 for prefaced concrete and calcium silicatemasonry units.

2103.2 Clay or shale masonry units. Clay or shale masonryunits shall conform to the following standards: ASTM C 34for structural clay load-bearing wall tile; ASTM C 56 forstructural clay nonload-bearing wall tile; ASTM C 62 forbuilding brick (solid masonry units made from clay or shale);ASTM C 1088 for solid units of thin veneer brick; ASTM C126 for ceramic-glazed structural clay facing tile, facing brickand solid masonry units; ASTM C 212 for structural clay fac-ing tile; ASTM C 216 for facing brick (solid masonry unitsmade from clay or shale); ASTM C 652 for hollow brick(hollow masonry units made from clay or shale) or ASTM C1405 for glazed brick (single-fired solid brick units).

Exception: Structural clay tile for nonstructural use infireproofing of structural members and in wall furringshall not be required to meet the compressive strengthspecifications. The fire-resistance rating shall be deter-mined in accordance with ASTM E 119 or UL 263 andshall comply with the requirements of Table 602.

2103.3 AAC masonry. AAC masonry units shall conform toASTM C 1386 for the strength class specified.

2103.4 Stone masonry units. Stone masonry units shall con-form to the following standards: ASTM C 503 for marblebuilding stone (exterior); ASTM C 568 for limestone build-ing stone; ASTM C 615 for granite building stone; ASTM C616 for sandstone building stone; or ASTM C 629 for slatebuilding stone.

2103.5 Architectural cast stone. Architectural cast stoneshall conform to ASTM C 1364.

2103.6 Ceramic tile. Ceramic tile shall be as defined in, andshall conform to the requirements of, ANSI A137.1.

2103.7 Glass unit masonry. Hollow glass units shall be par-tially evacuated and have a minimum average glass facethickness of 3/16 inch (4.8 mm). Solid glass-block units shallbe provided when required. The surfaces of units intended tobe in contact with mortar shall be treated with a polyvinylbutyral coating or latex-based paint. Reclaimed units shall notbe used.

2103.8 Second-hand units. Second-hand masonry units shallnot be reused unless they conform to the requirements of newunits. The units shall be of whole, sound materials and freefrom cracks and other defects that will interfere with properlaying or use. Old mortar shall be cleaned from the unitbefore reuse.

2103.9 Mortar. Mortar for use in masonry construction shallconform to ASTM C 270 and Articles 2.1 and 2.6 A of TMS602/ACI 530.1/ASCE 6, except for mortars listed in Sections2103.10, 2103.11 and 2103.12. Type S or N mortar conform-ing to ASTM C 270 shall be used for glass unit masonry.

2103.10 Surface-bonding mortar. Surface-bonding mortarshall comply with ASTM C 887. Surface bonding of concretemasonry units shall comply with ASTM C 946.

2103.11 Mortars for ceramic wall and floor tile. Portlandcement mortars for installing ceramic wall and floor tile shallcomply with ANSI A108.1A and ANSI A108.1B and be ofthe compositions indicated in Table 2103.11.

TABLE 2103.11CERAMIC TILE MORTAR COMPOSITIONS

2103.11.1 Dry-set Portland cement mortars. Premixedprepared Portland cement mortars, which require only theaddition of water and are used in the installation ofceramic tile, shall comply with ANSI A118.1. The shearbond strength for tile set in such mortar shall be asrequired in accordance with ANSI A118.1. Tile set in dry-set Portland cement mortar shall be installed in accordancewith ANSI A108.5.

2103.11.2 Latex-modified Portland cement mortar.Latex-modified Portland cement thin-set mortars in whichlatex is added to dry-set mortar as a replacement for all orpart of the gauging water that are used for the installationof ceramic tile shall comply with ANSI A118.4. Tile set inlatex-modified Portland cement shall be installed in accor-dance with ANSI A108.5.

2103.11.3 Epoxy mortar. Ceramic tile set and groutedwith chemical-resistant epoxy shall comply with ANSIA118.3. Tile set and grouted with epoxy shall be installedin accordance with ANSI A108.6.

2103.11.4 Furan mortar and grout. Chemical-resistantfuran mortar and grout that are used to install ceramic tileshall comply with ANSI A118.5. Tile set and grouted withfuran shall be installed in accordance with ANSI A108.8.

2103.11.5 Modified epoxy-emulsion mortar and grout.Modified epoxy-emulsion mortar and grout that are usedto install ceramic tile shall comply with ANSI A118.8.Tile set and grouted with modified epoxy-emulsion mortarand grout shall be installed in accordance with ANSIA108.9.

2103.11.6 Organic adhesives. Water-resistant organicadhesives used for the installation of ceramic tile shallcomply with ANSI A136.1. The shear bond strength afterwater immersion shall not be less than 40 psi (275 kPa) forType I adhesive and not less than 20 psi (138 kPa) forType II adhesive when tested in accordance with ANSIA136.1. Tile set in organic adhesives shall be installed inaccordance with ANSI A108.4.

LOCATION MORTAR COMPOSITION

Walls

Scratchcoat1 cement;1/5 hydrated lime;

4 dry or 5 damp sand

Setting bed and leveling coat

1 cement;1/2 hydrated lime;5 damp sand to 1 cement

1 hydrated lime, 7 damp sand

Floors Setting bed1 cement;1/10 hydrated lime;5 dry or 6 damp sand; or 1

cement; 5 dry or 6 damp sand

Ceilings Scratchcoat and sand bed

1 cement;1/2 hydrated lime;21/2 dry sand or 3 damp sand


MASONRY


2103.11.7 Portland cement grouts. Portland cementgrouts used for the installation of ceramic tile shall complywith ANSI A118.6. Portland cement grouts for tile workshall be installed in accordance with ANSI A108.10.

2103.12 Mortar for AAC masonry. Thin-bed mortar forAAC masonry shall comply with Article 2.1 C.1 of TMS 602/ACI 530.1/ASCE 6. Mortar used for the leveling courses ofAAC masonry shall comply with Article 2.1 C.2 of TMS 602/ACI 530.1/ASCE 6.

2103.13 Grout. Grout shall comply with Article 2.2 of TMS602/ACI 530.1/ASCE 6.

2103.14 Metal reinforcement and accessories. Metal rein-forcement and accessories shall conform to Article 2.4 ofTMS 602/ACI 530.1/ASCE 6. Where unidentified reinforce-ment is approved for use, not less than three tension and threebending tests shall be made on representative specimens ofthe reinforcement from each shipment and grade of reinforc-ing steel proposed for use in the work.

SECTION 2104CONSTRUCTION

2104.1 Masonry construction. Masonry construction shallcomply with the requirements of Sections 2104.1.1 through2104.4 and with TMS 602/ACI 530.1/ASCE 6.

2104.1.1 Tolerances. Masonry, except masonry veneer,shall be constructed within the tolerances specified inTMS 602/ACI 530.1/ASCE 6.

2104.1.2 Placing mortar and units. Placement of mortar,grout, and clay, concrete, glass, and AAC masonry unitsshall comply with TMS 602/ACI 530.1/ASCE 6.

2104.1.3 Installation of wall ties. Wall ties shall beinstalled in accordance with TMS 602/ACI 530.1/ASCE 6.

2104.1.4 Chases and recesses. Chases and recesses shallbe constructed as masonry units are laid. Masonry directlyabove chases or recesses wider than 12 inches (305 mm)shall be supported on lintels.

2104.1.5 Lintels. The design for lintels shall be in accor-dance with the masonry design provisions of either Sec-tion 2107 or 2108.

2104.1.6 Support on wood. Masonry shall not be sup-ported on wood girders or other forms of wood construc-tion except as permitted in Section 2304.12.

2104.2 Corbeled masonry. Corbeled masonry shall complywith the requirements of Section 1.12 of TMS 402/ACI 530/ASCE 5.

2104.2.1 Molded cornices. Unless structural support andanchorage are provided to resist the overturning moment,the center of gravity of projecting masonry or molded cor-nices shall lie within the middle one-third of the support-ing wall. Terra cotta and metal cornices shall be providedwith a structural frame of approved noncombustible mate-rial anchored in an approved manner.

2104.3 Cold weather construction. The cold weather con-struction provisions of TMS 602/ACI 530.1/ASCE 6, Article1.8 C, shall be implemented when the ambient temperaturefalls below 40°F (4°C).

2104.4 Hot weather construction. The hot weather con-struction provisions of TMS 602/ACI 530.1/ASCE 6, Article1.8 D, shall be implemented when the ambient air tempera-ture exceeds 100°F (37.8°C), or 90°F (32.2°C) with a windvelocity greater than 8 mph (12.9 km/hr).

SECTION 2105QUALITY ASSURANCE

2105.1 General. A quality assurance program shall be usedto ensure that the constructed masonry is in compliance withthe construction documents.

The quality assurance program shall comply with theinspection and testing requirements of Chapter 17.

2105.2 Acceptance relative to strength requirements.Where required by Chapter 17, verification of the strength ofmasonry shall be in accordance with Sections 2105.2.1 and2105.2.2.

2105.2.1 Compliance with f ′m and f ′AAC. Compressivestrength of masonry shall be considered satisfactory if thecompressive strength of each masonry wythe and groutedcollar joint equals or exceeds the value of f ′m for clay andconcrete masonry and f ′AAC for AAC masonry. For par-tially grouted clay and concrete masonry, the compressivestrength of both the grouted and ungrouted masonry shallequal or exceed the applicable f ′m. At the time of prestress,the compressive strength of the masonry shall equal orexceed f ′mi, which shall be less than or equal to f ′m.

2105.2.2 Determination of compressive strength. Thecompressive strength for each wythe shall be determinedby the unit strength method or by the prism test method asspecified herein.

2105.2.2.1 Unit strength method. The determinationof compressive strength by the unit strength methodshall be in accordance with Section 2105.2.2.1.1 forclay masonry, Section 2105.2.2.1.2 for concretemasonry and Section 2105.2.2.1.3 for AAC masonry.

2105.2.2.1.1 Clay masonry. The compressivestrength of masonry shall be determined based onthe strength of the units and the type of mortar spec-ified using Table 2105.2.2.1.1, provided:

1. Units are sampled and tested to verify compli-ance with ASTM C 62, ASTM C 216 orASTM C 652.

2. Thickness of bed joints does not exceed 5/8

inch (15.9 mm).

3. For grouted masonry, the grout meets one ofthe following requirements:

3.1. Grout conforms to Article 2.2 of TMS602/ACI 530.1/ASCE 6.

ñ

ñ

21_Seattle_Build_2012.fm 92 Wednesday, November 13, 2013 8:54 AM

MASONRY


3.2. Minimum grout compressive strengthequals or exceeds f ′m but not less than2,000 psi (13.79 MPa). Thecompressive strength of grout shall bedetermined in accordance with ASTMC 1019.

TABLE 2105.2.2.1.1COMPRESSIVE STRENGTH OF CLAY MASONRY

For SI: 1 pound per square inch = 0.00689 MPa.

2105.2.2.1.2 Concrete masonry. The compressivestrength of masonry shall be determined based onthe strength of the unit and type of mortar specifiedusing Table 2105.2.2.1.2, provided:

1. Units are sampled and tested to verify compli-ance with ASTM C 55 or ASTM C 90.


inch (15.9 mm).



3.2. Minimum grout compressive strengthequals or exceeds f ′m but not less than2,000 psi (13.79 MPa). Thecompressive strength of grout shall bedetermined in accordance with ASTMC 1019.

TABLE 2105.2.2.1.2COMPRESSIVE STRENGTH OF CONCRETE MASONRY

For SI: 1 inch = 25.4 mm, 1 pound per square inch = 0.00689 MPa.a. For units less than 4 inches in height, 85 percent of the values listed.

2105.2.2.1.3 AAC masonry. The compressivestrength of AAC masonry shall be based on thestrength of the AAC masonry unit only and the fol-lowing shall be met:

1. Units conform to ASTM C 1386.


inch (3.2 mm).



3.2. Minimum grout compressive strengthequals or exceeds f ′AAC but not lessthan 2,000 psi (13.79 MPa). Thecompressive strength of grout shall bedetermined in accordance with ASTMC 1019.

2105.2.2.2 Prism test method. The determination ofcompressive strength by the prism test method shall bein accordance with Sections 2105.2.2.2.1 and2105.2.2.2.2.

2105.2.2.2.1 General. The compressive strength ofclay and concrete masonry shall be determined bythe prism test method:

1. Where specified in the construction docu-ments.

2. Where masonry does not meet the require-ments for application of the unit strengthmethod in Section 2105.2.2.1.

2105.2.2.2.2 Number of prisms per test. A prismtest shall consist of three prisms constructed andtested in accordance with ASTM C 1314.

2105.3 Testing prisms from constructed masonry. Whenapproved by the building official, acceptance of masonry thatdoes not meet the requirements of Section 2105.2.2.1 or2105.2.2.2 shall be permitted to be based on tests of prismscut from the masonry construction in accordance with Sec-tions 2105.3.1, 2105.3.2 and 2105.3.3.

2105.3.1 Prism sampling and removal. A set of threemasonry prisms that are at least 28 days old shall be sawcut from the masonry for each 5,000 square feet (465 m2)of the wall area that is in question but not less than one setof three masonry prisms for the project. The length, widthand height dimensions of the prisms shall comply with therequirements of ASTM C 1314. Transporting, preparationand testing of prisms shall be in accordance with ASTM C1314.

2105.3.2 Compressive strength calculations. The com-pressive strength of prisms shall be the value calculated inaccordance ASTM C 1314, except that the net cross-sec-tional area of the prism shall be based on the net mortarbedded area.

NET AREA COMPRESSIVE STRENGTHOF CLAY MASONRY UNITS (psi) NET AREA COMPRESSIVE

STRENGTH OF MASONRY (psi)Type M or S mortar Type N mortar

1,700 2,100 1,000

3,350 4,150 1,500

4,950 6,200 2,000

6,600 8,250 2,500

8,250 10,300 3,000

9,900 — 3,500

11,500 — 4,000

NET AREA COMPRESSIVESTRENGTH OF CONCRETE

MASONRY UNITS (psi)NET AREA COMPRESSIVE

STRENGTH OF MASONRY (psi)a

Type M or S mortar Type N mortar

1,250 1,300 1,000

1,900 2,150 1,500

2,800 3,050 2,000

3,750 4,050 2,500

4,800 5,250 3,000


MASONRY


2105.3.3 Compliance. Compliance with the requirementfor the specified compressive strength of masonry, f ′m,shall be considered satisfied provided the modified com-pressive strength equals or exceeds the specified f ′m.Additional testing of specimens cut from locations inquestion shall be permitted.

SECTION 2106SEISMIC DESIGN

2106.1 Seismic design requirements for masonry. Masonrystructures and components shall comply with the require-ments in Section 1.18 of TMS 402/ACI 530/ASCE 5 depend-ing on the structure’s seismic design category.

SECTION 2107ALLOWABLE STRESS DESIGN

2107.1 General. The design of masonry structures usingallowable stress design shall comply with Section 2106 andthe requirements of Chapters 1 and 2 of TMS 402/ACI 530/ASCE 5 except as modified by Sections 2107.2 through2107.4.

2107.2 TMS 402/ACI 530/ASCE 5, Section 2.1.7.7.1.1, lapsplices. In lieu of Section 2.1.7.7.1.1, it shall be permitted todesign lap splices in accordance with Section 2107.2.1.

[W] 2107.2.1 Lap splices. The minimum length of lapsplices for reinforcing bars in tension or compression, ld,shall be

ld = 0.002db fs (Equation 21-1)

For SI: ld = 0.29db fs

but not less than 12 inches (305 mm). In no case shall thelength of the lapped splice be less than 40 bar diameters.

where:

db = Diameter of reinforcement, inches (mm).

fs = Computed stress in reinforcement due to designloads, psi (MPa).

In regions of moment where the design tensile stressesin the reinforcement are greater than 80 percent of theallowable steel tension stress, Fs, the lap length of splicesshall be increased not less than 50 percent of the minimumrequired length but need not be greater than 72db. Otherequivalent means of stress transfer to accomplish the same50 percent increase shall be permitted. Where epoxycoated bars are used, lap length shall be increased by 50percent.

2107.3 TMS 402/ACI 530/ASCE 5, Section 2.1.7.7, splicesof reinforcement. Modify Section 2.1.7.7 as follows:

2.1.7.7 Splices of reinforcement. Lap splices, weldedsplices or mechanical splices are permitted in accordancewith the provisions of this section. All welding shall con-form to AWS D1.4. Welded splices shall be of ASTM A706 steel reinforcement. Reinforcement larger than No. 9

(M #29) shall be spliced using mechanical connections inaccordance with Section 2.1.7.7.3.

2107.4 TMS 402/ACI 530/ASCE 5, Section 2.3.7, maxi-mum bar size. Add the following to Chapter 2:

2.3.7 Maximum bar size. The bar diameter shall notexceed one-eighth of the nominal wall thickness and shallnot exceed one-quarter of the least dimension of the cell,course or collar joint in which it is placed.

[W] 2107.5 TMS 402/ACI 530/ASCE 5. Modify Section2.3.4 Axial compression and flexure, as follows:

2.3.4.2.1 The compressive force in reinforced masonrydue to axial load only shall be permitted to not exceed thatgiven by Equation 2-21 or Equation 2-22.

(a) For members having an h/r ratio not greater than 99:

Pa = (0.33 f ′mAn + 0.65Ast Fs) [1-(h/140r)2](Equation 2-21)

(b) For members having an h/r ratio not greater than 99:

Pa = (0.33 f ′mAn + 0.65Fs Ast) (70r/h)2 (Equation 2-22)

SECTION 2108STRENGTH DESIGN OF MASONRY

2108.1 General. The design of masonry structures usingstrength design shall comply with Section 2106 and therequirements of Chapters 1 and 3 of TMS 402/ACI 530/ASCE 5, except as modified by Sections 2108.2 through2108.3.

Exception: AAC masonry shall comply with the require-ments of Chapters 1 and 8 of TMS 402/ACI 530/ASCE 5.

2108.2 TMS 402/ACI 530/ASCE 5, Section 3.3.3.3 devel-opment. Modify the second paragraph of Section 3.3.3.3 asfollows:

The required development length of reinforcement shall bedetermined by Equation (3-16), but shall not be less than12 inches (305 mm) and need not be greater than 72 db.

2108.3 TMS 402/ACI 530/ASCE 5, Section 3.3.3.4, splices.Modify items (c) and (d) of Section 3.3.3.4 as follows:

3.3.3.4 (c). A welded splice shall have the bars butted andwelded to develop at least 125 percent of the yieldstrength, ƒy, of the bar in tension or compression, asrequired. Welded splices shall be of ASTM A 706 steelreinforcement. Welded splices shall not be permitted inplastic hinge zones of intermediate or special reinforcedwalls or special moment frames of masonry.

3.3.3.4 (d). Mechanical splices shall be classified as Type1 or 2 according to Section 21.2.6.1 of ACI 318. Type 1mechanical splices shall not be used within a plastic hingezone or within a beam-column joint of intermediate or spe-cial reinforced masonry shear walls or special momentframes. Type 2 mechanical splices are permitted in anylocation within a member.

ñ

ñ

ñ


MASONRY


SECTION 2109EMPIRICAL DESIGN OF MASONRY

2109.1 General. Empirically designed masonry shall con-form to the requirements of Chapter 5 of TMS 402/ACI 530/ASCE 5, except where otherwise noted in this section.

2109.1.1 Limitations. The use of empirical design ofmasonry shall be limited as noted in Section 5.1.2 of TMS402/ACI 530/ASCE 5. The use of dry-stacked, surface-bonded masonry shall be prohibited in Risk Category IVstructures. In buildings that exceed one or more of the lim-itations of Section 5.1.2 of TMS 402/ACI 530/ASCE 5,masonry shall be designed in accordance with the engi-neered design provisions of Section 2101.2.1, 2101.2.2 or2101.2.3 or the foundation wall provisions of Section1807.1.5.

Section 5.1.2.2 of TMS 402/ACI 530/ASCE 5 shall bemodified as follows:

5.1.2.2 Wind – Empirical requirements shall not applyto the design or construction of masonry for buildings,parts of buildings, or other structures to be located inareas where Vasd as determined in accordance with Sec-tion 1609.3.1 of the International Building Codeexceeds 110 mph.

2109.2 Surface-bonded walls. Dry-stacked, surface-bondedconcrete masonry walls shall comply with the requirementsof Chapter 5 of TMS 402/ACI 530/ASCE 5, except whereotherwise noted in this section.

2109.2.1 Strength. Dry-stacked, surface-bonded concretemasonry walls shall be of adequate strength and propor-tions to support all superimposed loads without exceedingthe allowable stresses listed in Table 2109.2.1. Allowablestresses not specified in Table 2109.2.1 shall comply withthe requirements of TMS 402/ACI 530/ASCE 5.

TABLE 2109.2.1ALLOWABLE STRESS GROSS CROSS-SECTIONAL

AREA FOR DRY-STACKED, SURFACE-BONDED CONCRETE MASONRY WALLS

For SI: 1 pound per square inch = 0.006895 MPa.

2109.2.2 Construction. Construction of dry-stacked, sur-face-bonded masonry walls, including stacking and level-ing of units, mixing and application of mortar and curingand protection shall comply with ASTM C 946.

2109.3 Adobe construction. Adobe construction shall com-ply with this section and shall be subject to the requirementsof this code for Type V construction, Chapter 5 of TMS 402/ACI 530/ASCE 5, and this section.

2109.3.1 Unstabilized adobe. Unstabilized adobe shallcomply with Sections 2109.3.1.1 through 2109.3.1.4.

2109.3.1.1 Compressive strength. Adobe units shallhave an average compressive strength of 300 psi (2068

kPa) when tested in accordance with ASTM C 67. Fivesamples shall be tested and no individual unit is permit-ted to have a compressive strength of less than 250 psi(1724 kPa).

2109.3.1.2 Modulus of rupture. Adobe units shallhave an average modulus of rupture of 50 psi (345 kPa)when tested in accordance with the following proce-dure. Five samples shall be tested and no individualunit shall have a modulus of rupture of less than 35 psi(241 kPa).

2109.3.1.2.1 Support conditions. A cured unit shallbe simply supported by 2-inch-diameter (51 mm)cylindrical supports located 2 inches (51 mm) infrom each end and extending the full width of theunit.

2109.3.1.2.2 Loading conditions. A 2-inch-diame-ter (51 mm) cylinder shall be placed at midspan par-allel to the supports.

2109.3.1.2.3 Testing procedure. A vertical loadshall be applied to the cylinder at the rate of 500pounds per minute (37 N/s) until failure occurs.

2109.3.1.2.4 Modulus of rupture determination.The modulus of rupture shall be determined by theequation:

f r = 3 PLs /2 Sw (St2) (Equation 21-2)

where, for the purposes of this section only:

Sw = Width of the test specimen measured parallelto the loading cylinder, inches (mm).

fr = Modulus of rupture, psi (MPa).

Ls = Distance between supports, inches (mm).

St = Thickness of the test specimen measuredparallel to the direction of load, inches (mm).

P = The applied load at failure, pounds (N).

2109.3.1.3 Moisture content requirements. Adobeunits shall have a moisture content not exceeding 4 per-cent by weight.

2109.3.1.4 Shrinkage cracks. Adobe units shall notcontain more than three shrinkage cracks and any sin-gle shrinkage crack shall not exceed 3 inches (76 mm)in length or 1/8 inch (3.2 mm) in width.

2109.3.2 Stabilized adobe. Stabilized adobe shall complywith Section 2109.3.1 for unstabilized adobe in addition toSections 2109.3.2.1 and 2109.3.2.2.

2109.3.2.1 Soil requirements. Soil used for stabilizedadobe units shall be chemically compatible with thestabilizing material.

2109.3.2.2 Absorption requirements. A 4-inch (102mm) cube, cut from a stabilized adobe unit dried to aconstant weight in a ventilated oven at 212°F to 239°F(100°C to 115°C), shall not absorb more than 21/2 per-cent moisture by weight when placed upon a constantlywater-saturated, porous surface for seven days. A mini-mum of five specimens shall be tested and each speci-men shall be cut from a separate unit.

DESCRIPTION MAXIMUM ALLOWABLE STRESS (psi)

Compression standard block 45

Flexural tensionHorizontal spanVertical span

3018

Shear 10


MASONRY


2109.3.3 Allowable stress. The allowable compressivestress based on gross cross-sectional area of adobe shallnot exceed 30 psi (207 kPa).

2109.3.3.1 Bolts. Bolt values shall not exceed those setforth in Table 2109.3.3.1.

TABLE 2109.3.3.1ALLOWABLE SHEAR ON BOLTS IN ADOBE MASONRY

For SI: 1 inch = 25.4 mm, 1 pound = 4.448 N.

2109.3.4 Detailed requirements. Adobe constructionshall comply with Sections 2109.3.4.1 through 2109.3.4.9.

2109.3.4.1 Number of stories. Adobe constructionshall be limited to buildings not exceeding one story,except that two-story construction is allowed whendesigned by a registered design professional.

2109.3.4.2 Mortar. Mortar for adobe constructionshall comply with Sections 2109.3.4.2.1 and2109.3.4.2.2.

2109.3.4.2.1 General. Mortar for stabilized adobeunits shall comply with Chapter 21 or adobe soil.Adobe soil used as mortar shall comply with mate-rial requirements for stabilized adobe. Mortar forunstabilized adobe shall be Portland cement mortar.

2109.3.4.2.2 Mortar joints. Adobe units shall belaid with full head and bed joints and in full runningbond.

2109.3.4.3 Parapet walls. Parapet walls constructed ofadobe units shall be waterproofed.

2109.3.4.4 Wall thickness. The minimum thickness ofexterior walls in one-story buildings shall be 10 inches(254 mm). The walls shall be laterally supported atintervals not exceeding 24 feet (7315 mm). The mini-mum thickness of interior load-bearing walls shall be 8inches (203 mm). In no case shall the unsupportedheight of any wall constructed of adobe units exceed 10times the thickness of such wall.

2109.3.4.5 Foundations. Foundations for adobe con-struction shall be in accordance with Sections2109.3.4.5.1 and 2109.3.4.5.2.

2109.3.4.5.1 Foundation support. Walls and parti-tions constructed of adobe units shall be supportedby foundations or footings that extend not less than6 inches (152 mm) above adjacent ground surfacesand are constructed of solid masonry (excludingadobe) or concrete. Footings and foundations shallcomply with Chapter 18.

2109.3.4.5.2 Lower course requirements. Stabi-lized adobe units shall be used in adobe walls for thefirst 4 inches (102 mm) above the finished first-floorelevation.

2109.3.4.6 Isolated piers or columns. Adobe unitsshall not be used for isolated piers or columns in a load-bearing capacity. Walls less than 24 inches (610 mm)in length shall be considered isolated piers or columns.

2109.3.4.7 Tie beams. Exterior walls and interior load-bearing walls constructed of adobe units shall have acontinuous tie beam at the level of the floor or roofbearing and meeting the following requirements.

2109.3.4.7.1 Concrete tie beams. Concrete tiebeams shall be a minimum depth of 6 inches (152mm) and a minimum width of 10 inches (254 mm).Concrete tie beams shall be continuously reinforcedwith a minimum of two No. 4 reinforcing bars. Thespecified compressive strength of concrete shall beat least 2,500 psi (17.2 MPa).

2109.3.4.7.2 Wood tie beams. Wood tie beamsshall be solid or built up of lumber having a mini-mum nominal thickness of 1 inch (25 mm), and shallhave a minimum depth of 6 inches (152 mm) and aminimum width of 10 inches (254 mm). Joints inwood tie beams shall be spliced a minimum of 6inches (152 mm). No splices shall be allowed within12 inches (305 mm) of an opening. Wood used in tiebeams shall be approved naturally decay-resistant orpreservative-treated wood.

2109.3.4.8 Exterior finish. Exterior walls constructedof unstabilized adobe units shall have their exterior sur-face covered with a minimum of two coats of Portlandcement plaster having a minimum thickness of 3/4 inch(19.1 mm) and conforming to ASTM C 926. Lathingshall comply with ASTM C 1063. Fasteners shall bespaced at 16 inches (406 mm) o.c. maximum. Exposedwood surfaces shall be treated with an approved woodpreservative or other protective coating prior to lathapplication.

2109.3.4.9 Lintels. Lintels shall be considered struc-tural members and shall be designed in accordance withthe applicable provisions of Chapter 16.

SECTION 2110GLASS UNIT MASONRY

2110.1 General. Glass unit masonry construction shall com-ply with Chapter 7 of TMS 402/ACI 530/ASCE 5 and thissection.

2110.1.1 Limitations. Solid or hollow approved glassblock shall not be used in fire walls, party walls, fire barri-ers, fire partitions or smoke barriers, or for load-bearingconstruction. Such blocks shall be erected with mortar andreinforcement in metal channel-type frames, structuralframes, masonry or concrete recesses, embedded panelanchors as provided for both exterior and interior walls or

DIAMETER OF BOLTS (inches)

MINIMUM EMBEDMENT (inches)

SHEAR (pounds)

1/2 — —5/8 12 2003/4 15 3007/8 18 400

1 21 500

11/8 24 600

�


MASONRY


other approved joint materials. Wood strip framing shallnot be used in walls required to have a fire-resistance rat-ing by other provisions of this code.

Exceptions:

1. Glass-block assemblies having a fire protectionrating of not less than 3/4 hour shall be permittedas opening protectives in accordance with Sec-tion 716 in fire barriers, fire partitions and smokebarriers that have a required fire-resistance ratingof 1 hour or less and do not enclose exit stair-ways, exit ramps or exit passageways.

2. Glass-block assemblies as permitted in Section404.6, Exception 2.

SECTION 2111MASONRY FIREPLACES

2111.1 Definition. A masonry fireplace is a fireplace con-structed of concrete or masonry. Masonry fireplaces shall beconstructed in accordance with this section.

2111.2 Footings and foundations. Footings for masonryfireplaces and their chimneys shall be constructed of concreteor solid masonry at least 12 inches (305 mm) thick and shallextend at least 6 inches (153 mm) beyond the face of the fire-place or foundation wall on all sides. Footings shall befounded on natural undisturbed earth or engineered fill belowfrost depth. In areas not subjected to freezing, footings shallbe at least 12 inches (305 mm) below finished grade.

2111.2.1 Ash dump cleanout. Cleanout openings, locatedwithin foundation walls below fireboxes, when provided,shall be equipped with ferrous metal or masonry doors andframes constructed to remain tightly closed, except whenin use. Cleanouts shall be accessible and located so thatash removal will not create a hazard to combustible mate-rials.

2111.3 Seismic reinforcing. In structures assigned to SeismicDesign Category A or B, reinforcement and seismic anchorageare not required. Masonry or concrete fireplaces shall be con-structed, anchored, supported and reinforced as required in thischapter. In structures assigned to Seismic Design Category Cor D, masonry and concrete fireplaces shall be reinforced andanchored as detailed in Sections 2111.3.1, 2111.3.2, 2111.4and 2111.4.1 for chimneys serving fireplaces. In structuresassigned to Seismic Design Category E or F, masonry and con-crete chimneys shall be reinforced in accordance with therequirements of Sections 2101 through 2108.

2111.3.1 Vertical reinforcing. For fireplaces with chim-neys up to 40 inches (1016 mm) wide, four No. 4 continu-ous vertical bars, anchored in the foundation, shall beplaced in the concrete between wythes of solid masonry orwithin the cells of hollow unit masonry and grouted inaccordance with Section 2103.13. For fireplaces with chim-neys greater than 40 inches (1016 mm) wide, two additionalNo. 4 vertical bars shall be provided for each additional 40inches (1016 mm) in width or fraction thereof.

2111.3.2 Horizontal reinforcing. Vertical reinforcementshall be placed enclosed within 1/4-inch (6.4 mm) ties or

other reinforcing of equivalent net cross-sectional area,spaced not to exceed 18 inches (457 mm) on center in con-crete; or placed in the bed joints of unit masonry at a mini-mum of every 18 inches (457 mm) of vertical height. Twosuch ties shall be provided at each bend in the vertical bars.

2111.4 Seismic anchorage. Masonry and concrete chimneysin structures assigned to Seismic Design Category C or Dshall be anchored at each floor, ceiling or roof line more than6 feet (1829 mm) above grade, except where constructedcompletely within the exterior walls. Anchorage shall con-form to the following requirements.

2111.4.1 Anchorage. Two 3/16-inch by 1-inch (4.8 mm by25.4 mm) straps shall be embedded a minimum of 12inches (305 mm) into the chimney. Straps shall be hookedaround the outer bars and extend 6 inches (152 mm)beyond the bend. Each strap shall be fastened to a mini-mum of four floor joists with two 1/2-inch (12.7 mm) bolts.

2111.5 Firebox walls. Masonry fireboxes shall be con-structed of solid masonry units, hollow masonry units groutedsolid, stone or concrete. When a lining of firebrick at least 2inches (51 mm) in thickness or other approved lining is pro-vided, the minimum thickness of back and sidewalls shalleach be 8 inches (203 mm) of solid masonry, including thelining. The width of joints between firebricks shall not begreater than 1/4 inch (6.4 mm). When no lining is provided,the total minimum thickness of back and sidewalls shall be 10inches (254 mm) of solid masonry. Firebrick shall conform toASTM C 27 or ASTM C 1261 and shall be laid with medium-duty refractory mortar conforming to ASTM C 199.

2111.5.1 Steel fireplace units. Steel fireplace units arepermitted to be installed with solid masonry to form amasonry fireplace provided they are installed according toeither the requirements of their listing or the requirementsof this section. Steel fireplace units incorporating a steelfirebox lining shall be constructed with steel not less than1/4 inch (6.4 mm) in thickness, and an air-circulating cham-ber which is ducted to the interior of the building. The fire-box lining shall be encased with solid masonry to providea total thickness at the back and sides of not less than 8inches (203 mm), of which not less than 4 inches (102mm) shall be of solid masonry or concrete. Circulating airducts employed with steel fireplace units shall be con-structed of metal or masonry.

2111.6 Firebox dimensions. The firebox of a concrete ormasonry fireplace shall have a minimum depth of 20 inches(508 mm). The throat shall not be less than 8 inches (203mm) above the fireplace opening. The throat opening shallnot be less than 4 inches (102 mm) in depth. The cross-sec-tional area of the passageway above the firebox, including thethroat, damper and smoke chamber, shall not be less than thecross-sectional area of the flue.

Exception: Rumford fireplaces shall be permitted pro-vided that the depth of the fireplace is at least 12 inches(305 mm) and at least one-third of the width of the fire-place opening, and the throat is at least 12 inches (305mm) above the lintel, and at least 1/20 the cross-sectionalarea of the fireplace opening.


MASONRY


[W] 2111.7 Fireplaces. Fireplaces shall be provided witheach of the following:

1. Tightly fitting flue dampers, operated by a readilyaccessible manual or approved automatic control.

Exception: Fireplaces with gas logs shall beinstalled in accordance with International Mechani-cal Code Section 901, except that the standards forliquefied petroleum gas installations shall be NFPA58 (Liquefied Petroleum Gas Code) and NFPA 54(National Fuel Gas Code).

2. An outside source for combustion air ducted into thefirebox. The duct shall be at least 6 square inches andshall be provided with an operable outside air ductdamper.

Exception: Washington certified fireplaces shall beinstalled with the combustion air systems necessaryfor their safe and efficient combustion and as speci-fied by the manufacturer in accordance with Section2114.

3. Site built fireplaces shall have tight fitting glass ormetal doors, or a flue draft induction fan or as approvedfor minimizing back-drafting. Factory built fireplacesshall use doors listed for the installed appliance.

2111.7.1 Lintel and throat. Masonry over a fireplaceopening shall be supported by a lintel of noncombustiblematerial. The minimum required bearing length on each endof the fireplace opening shall be 4 inches (102 mm). Thefireplace throat or damper shall be located a minimum of 8inches (203 mm) above the top of the fireplace opening.

((2111.7.1)) 2111.7.2 Damper. Masonry fireplaces shallbe equipped with a ferrous metal damper located at least 8inches (203 mm) above the top of the fireplace opening.Dampers shall be installed in the fireplace or at the top ofthe flue venting the fireplace, and shall be operable fromthe room containing the fireplace. Damper controls shallbe permitted to be located in the fireplace.

2111.8 Smoke chamber walls. Smoke chamber walls shallbe constructed of solid masonry units, hollow masonry unitsgrouted solid, stone or concrete. The total minimum thicknessof front, back and sidewalls shall be 8 inches (203 mm) ofsolid masonry. The inside surface shall be parged smoothwith refractory mortar conforming to ASTM C 199. When alining of firebrick at least 2 inches (51 mm) thick, or a liningof vitrified clay at least 5/8 inch (15.9 mm) thick, is provided,the total minimum thickness of front, back and sidewalls shallbe 6 inches (152 mm) of solid masonry, including the lining.Firebrick shall conform to ASTM C 1261 and shall be laidwith refractory mortar conforming to ASTM C 199. Vitrifiedclay linings shall conform to ASTM C 315.

2111.8.1 Smoke chamber dimensions. The inside heightof the smoke chamber from the fireplace throat to thebeginning of the flue shall not be greater than the insidewidth of the fireplace opening. The inside surface of thesmoke chamber shall not be inclined more than 45 degrees(0.76 rad) from vertical when prefabricated smoke cham-ber linings are used or when the smoke chamber walls arerolled or sloped rather than corbeled. When the inside sur-

face of the smoke chamber is formed by corbeledmasonry, the walls shall not be corbeled more than 30degrees (0.52 rad) from vertical.

2111.9 Hearth and hearth extension. Masonry fireplacehearths and hearth extensions shall be constructed of concreteor masonry, supported by noncombustible materials, andreinforced to carry their own weight and all imposed loads.No combustible material shall remain against the undersideof hearths or hearth extensions after construction.

2111.9.1 Hearth thickness. The minimum thickness offireplace hearths shall be 4 inches (102 mm).

2111.9.2 Hearth extension thickness. The minimumthickness of hearth extensions shall be 2 inches (51 mm).

Exception: When the bottom of the firebox opening israised at least 8 inches (203 mm) above the top of thehearth extension, a hearth extension of not less than 3/8-inch-thick (9.5 mm) brick, concrete, stone, tile or otherapproved noncombustible material is permitted.

2111.10 Hearth extension dimensions. Hearth extensionsshall extend at least 16 inches (406 mm) in front of, and atleast 8 inches (203 mm) beyond, each side of the fireplaceopening. Where the fireplace opening is 6 square feet (0.557m2) or larger, the hearth extension shall extend at least 20inches (508 mm) in front of, and at least 12 inches (305 mm)beyond, each side of the fireplace opening.

2111.11 Fireplace clearance. Any portion of a masonry fire-place located in the interior of a building or within the exte-rior wall of a building shall have a clearance to combustiblesof not less than 2 inches (51 mm) from the front faces andsides of masonry fireplaces and not less than 4 inches (102mm) from the back faces of masonry fireplaces. The airspaceshall not be filled, except to provide fireblocking in accor-dance with Section 2111.12.

Exceptions:

1. Masonry fireplaces listed and labeled for use in con-tact with combustibles in accordance with UL 127 andinstalled in accordance with the manufacturer's instal-lation instructions are permitted to have combustiblematerial in contact with their exterior surfaces.

2. When masonry fireplaces are constructed as part ofmasonry or concrete walls, combustible materialsshall not be in contact with the masonry or concretewalls less than 12 inches (306 mm) from the insidesurface of the nearest firebox lining.

3. Exposed combustible trim and the edges of sheath-ing materials, such as wood siding, flooring and dry-wall, are permitted to abut the masonry fireplacesidewalls and hearth extension, in accordance withFigure 2111.11, provided such combustible trim orsheathing is a minimum of 12 inches (306 mm) fromthe inside surface of the nearest firebox lining.

4. Exposed combustible mantels or trim is permitted tobe placed directly on the masonry fireplace frontsurrounding the fireplace opening, provided suchcombustible materials shall not be placed within 6inches (153 mm) of a fireplace opening. Combusti-


MASONRY


ble material directly above and within 12 inches(305 mm) of the fireplace opening shall not projectmore than 1/8 inch (3.2 mm) for each 1-inch (25 mm)distance from such opening. Combustible materialslocated along the sides of the fireplace opening thatproject more than 11/2 inches (38 mm) from the faceof the fireplace shall have an additional clearanceequal to the projection.

2111.12 Fireplace fireblocking. All spaces between fire-places and floors and ceilings through which fireplaces passshall be fireblocked with noncombustible material securelyfastened in place. The fireblocking of spaces between woodjoists, beams or headers shall be to a depth of 1 inch (25 mm)and shall only be placed on strips of metal or metal lath laidacross the spaces between combustible material and thechimney.

2111.13 Exterior air. Factory-built or masonry fireplacescovered in this section shall be equipped with an exterior airsupply to ensure proper fuel combustion unless the room ismechanically ventilated and controlled so that the indoorpressure is neutral or positive.

2111.13.1 Factory-built fireplaces. Exterior combustionair ducts for factory-built fireplaces shall be listed compo-nents of the fireplace, and installed according to the fire-place manufacturer's instructions.

2111.13.2 Masonry fireplaces. Listed combustion airducts for masonry fireplaces shall be installed according tothe terms of their listing and manufacturer's instructions.

2111.13.3 Exterior air intake. The exterior air intakeshall be capable of providing all combustion air from theexterior of the dwelling. The exterior air intake shall not belocated within a garage, attic, basement or crawl space ofthe dwelling nor shall the air intake be located at an eleva-tion higher than the firebox. The exterior air intake shallbe covered with a corrosion-resistant screen of 1/4-inch(6.4 mm) mesh.

2111.13.4 Clearance. Unlisted combustion air ducts shallbe installed with a minimum 1-inch (25 mm) clearance to

combustibles for all parts of the duct within 5 feet (1524mm) of the duct outlet.

2111.13.5 Passageway. The combustion air passagewayshall be a minimum of 6 square inches (3870 mm2) and notmore than 55 square inches (0.035 m2), except that com-bustion air systems for listed fireplaces or for fireplacestested for emissions shall be constructed according to thefireplace manufacturer's instructions.

2111.13.6 Outlet. The exterior air outlet is permitted to belocated in the back or sides of the firebox chamber orwithin 24 inches (610 mm) of the firebox opening on ornear the floor. The outlet shall be closable and designed toprevent burning material from dropping into concealedcombustible spaces.

SECTION 2112MASONRY HEATERS

2112.1 Definition. A masonry heater is a heating applianceconstructed of concrete or solid masonry, hereinafter referredto as “masonry,” which is designed to absorb and store heatfrom a solid fuel fire built in the firebox by routing theexhaust gases through internal heat exchange channels inwhich the flow path downstream of the firebox may includeflow in a horizontal or downward direction before enteringthe chimney and which delivers heat by radiation from themasonry surface of the heater.

2112.2 Installation. Masonry heaters shall be installed inaccordance with this section and comply with one of the fol-lowing:

1. Masonry heaters shall comply with the requirements ofASTM E 1602; or

2. Masonry heaters shall be listed and labeled in accor-dance with UL 1482 and installed in accordance withthe manufacturer's installation instructions.

2112.3 Footings and foundation. The firebox floor of amasonry heater shall be a minimum thickness of 4 inches(102 mm) of noncombustible material and be supported on anoncombustible footing and foundation in accordance withSection 2113.2.

2112.4 Seismic reinforcing. In structures assigned to SeismicDesign Category D, E or F, masonry heaters shall beanchored to the masonry foundation in accordance with Sec-tion 2113.3. Seismic reinforcing shall not be required withinthe body of a masonry heater with a height that is equal to orless than 3.5 times its body width and where the masonrychimney serving the heater is not supported by the body ofthe heater. Where the masonry chimney shares a commonwall with the facing of the masonry heater, the chimney por-tion of the structure shall be reinforced in accordance withSection 2113.

2112.5 Masonry heater clearance. Combustible materialsshall not be placed within 36 inches (765 mm) of the outsidesurface of a masonry heater in accordance with NFPA 211,Section 8-7 (clearances for solid fuel-burning appliances),

For SI: 1 inch = 25.4 mm

FIGURE 2111.11ILLUSTRATION OF EXCEPTION TO

FIREPLACE CLEARANCE PROVISION


MASONRY


and the required space between the heater and combustiblematerial shall be fully vented to permit the free flow of airaround all heater surfaces.

Exceptions:

1. When the masonry heater wall thickness is at least 8inches (203 mm) thick of solid masonry and the wallthickness of the heat exchange channels is at least 5inches (127 mm) thick of solid masonry, combusti-ble materials shall not be placed within 4 inches(102 mm) of the outside surface of a masonry heater.A clearance of at least 8 inches (203 mm) shall beprovided between the gas-tight capping slab of theheater and a combustible ceiling.

2. Masonry heaters listed and labeled in accordancewith UL 1482 and installed in accordance with themanufacturer's instructions.

SECTION 2113MASONRY CHIMNEYS

2113.1 Definition. A masonry chimney is a chimney con-structed of solid masonry units, hollow masonry units groutedsolid, stone or concrete, hereinafter referred to as “masonry.”Masonry chimneys shall be constructed, anchored, supportedand reinforced as required in this chapter.

2113.2 Footings and foundations. Footings for masonrychimneys shall be constructed of concrete or solid masonry atleast 12 inches (305 mm) thick and shall extend at least 6inches (152 mm) beyond the face of the foundation or supportwall on all sides. Footings shall be founded on natural undis-turbed earth or engineered fill below frost depth. In areas notsubjected to freezing, footings shall be at least 12 inches (305mm) below finished grade.

2113.3 Seismic reinforcing. Masonry or concrete chimneysshall be constructed, anchored, supported and reinforced asrequired in this chapter. In structures assigned to SeismicDesign Category C or D, masonry and concrete chimneysshall be reinforced and anchored as detailed in Sections2113.3.1, 2113.3.2 and 2113.4. In structures assigned to Seis-mic Design Category A or B, reinforcement and seismicanchorage is not required. In structures assigned to SeismicDesign Category E or F, masonry and concrete chimneysshall be reinforced in accordance with the requirements ofSections 2101 through 2108.

2113.3.1 Vertical reinforcing. For chimneys up to 40inches (1016 mm) wide, four No. 4 continuous verticalbars anchored in the foundation shall be placed in the con-crete between wythes of solid masonry or within the cellsof hollow unit masonry and grouted in accordance withSection 2103.13. Grout shall be prevented from bondingwith the flue liner so that the flue liner is free to move withthermal expansion. For chimneys greater than 40 inches(1016 mm) wide, two additional No. 4 vertical bars shallbe provided for each additional 40 inches (1016 mm) inwidth or fraction thereof.

2113.3.2 Horizontal reinforcing. Vertical reinforcementshall be placed enclosed within 1/4-inch (6.4 mm) ties, or

other reinforcing of equivalent net cross-sectional area,spaced not to exceed 18 inches (457 mm) o.c. in concrete,or placed in the bed joints of unit masonry, at a minimumof every 18 inches (457 mm) of vertical height. Two suchties shall be provided at each bend in the vertical bars.

2113.4 Seismic anchorage. Masonry and concrete chimneysand foundations in structures assigned to Seismic Design Cat-egory C or D shall be anchored at each floor, ceiling or roofline more than 6 feet (1829 mm) above grade, except whereconstructed completely within the exterior walls. Anchorageshall conform to the following requirements.

2113.4.1 Anchorage. Two 3/16-inch by 1-inch (4.8 mm by25 mm) straps shall be embedded a minimum of 12 inches(305 mm) into the chimney. Straps shall be hooked aroundthe outer bars and extend 6 inches (152 mm) beyond thebend. Each strap shall be fastened to a minimum of fourfloor joists with two 1/2-inch (12.7 mm) bolts.

2113.5 Corbeling. Masonry chimneys shall not be corbeledmore than half of the chimney's wall thickness from a wall orfoundation, nor shall a chimney be corbeled from a wall orfoundation that is less than 12 inches (305 mm) in thicknessunless it projects equally on each side of the wall, except thaton the second story of a two-story dwelling, corbeling ofchimneys on the exterior of the enclosing walls is permittedto equal the wall thickness. The projection of a single courseshall not exceed one-half the unit height or one-third of theunit bed depth, whichever is less.

2113.6 Changes in dimension. The chimney wall or chim-ney flue lining shall not change in size or shape within 6inches (152 mm) above or below where the chimney passesthrough floor components, ceiling components or roof com-ponents.

2113.7 Offsets. Where a masonry chimney is constructedwith a fireclay flue liner surrounded by one wythe ofmasonry, the maximum offset shall be such that the centerlineof the flue above the offset does not extend beyond the centerof the chimney wall below the offset. Where the chimney off-set is supported by masonry below the offset in an approvedmanner, the maximum offset limitations shall not apply. Eachindividual corbeled masonry course of the offset shall notexceed the projection limitations specified in Section 2113.5.

2113.8 Additional load. Chimneys shall not support loadsother than their own weight unless they are designed and con-structed to support the additional load. Masonry chimneys arepermitted to be constructed as part of the masonry walls orconcrete walls of the building.

2113.9 Termination. Chimneys shall extend at least 2 feet(610 mm) higher than any portion of the building within 10feet (3048 mm), but shall not be less than 3 feet (914 mm)above the highest point where the chimney passes through theroof.

2113.9.1 Chimney caps. Masonry chimneys shall have aconcrete, metal or stone cap, sloped to shed water, a dripedge and a caulked bond break around any flue liners inaccordance with ASTM C 1283.


MASONRY


2113.9.2 Spark arrestors. Where a spark arrestor isinstalled on a masonry chimney, the spark arrestor shallmeet all of the following requirements:

1. The net free area of the arrestor shall not be less thanfour times the net free area of the outlet of the chim-ney flue it serves.

2. The arrestor screen shall have heat and corrosionresistance equivalent to 19-gage galvanized steel or24-gage stainless steel.

3. Openings shall not permit the passage of sphereshaving a diameter greater than 1/2 inch (12.7 mm)nor block the passage of spheres having a diameterless than 3/8 inch (9.5 mm).

4. The spark arrestor shall be accessible for cleaningand the screen or chimney cap shall be removable toallow for cleaning of the chimney flue.

2113.9.3 Rain caps. Where a masonry or metal rain cap isinstalled on a masonry chimney, the net free area under thecap shall not be less than four times the net free area of theoutlet of the chimney flue it serves.

2113.10 Wall thickness. Masonry chimney walls shall beconstructed of concrete, solid masonry units or hollowmasonry units grouted solid with not less than 4 inches (102mm) nominal thickness.

2113.10.1 Masonry veneer chimneys. Where masonry isused as veneer for a framed chimney, through flashing andweep holes shall be provided as required by Chapter 14.

2113.11 Flue lining (material). Masonry chimneys shall belined. The lining material shall be appropriate for the type ofappliance connected, according to the terms of the appliancelisting and the manufacturer’s instructions.

2113.11.1 Residential-type appliances (general). Fluelining systems shall comply with one of the following:

1. Clay flue lining complying with the requirements ofASTM C 315.

2. Listed chimney lining systems complying with UL1777.

3. Factory-built chimneys or chimney units listed forinstallation within masonry chimneys.

4. Other approved materials that will resist corrosion,erosion, softening or cracking from flue gases andcondensate at temperatures up to 1,800°F (982°C).

2113.11.1.1 Flue linings for specific appliances. Fluelinings other than those covered in Section 2113.11.1intended for use with specific appliances shall complywith Sections 2113.11.1.2 through 2113.11.1.4 andSections 2113.11.2 and 2113.11.3.

2113.11.1.2 Gas appliances. Flue lining systems forgas appliances shall be in accordance with the Interna-tional Fuel Gas Code.

2113.11.1.3 Pellet fuel-burning appliances. Flue lin-ing and vent systems for use in masonry chimneys withpellet fuel-burning appliances shall be limited to fluelining systems complying with Section 2113.11.1 and

pellet vents listed for installation within masonry chim-neys (see Section 2113.11.1.5 for marking).

2113.11.1.4 Oil-fired appliances approved for usewith L-vent. Flue lining and vent systems for use inmasonry chimneys with oil-fired appliances approvedfor use with Type L vent shall be limited to flue liningsystems complying with Section 2113.11.1 and listedchimney liners complying with UL 641 (see Section2113.11.1.5 for marking).

2113.11.1.5 Notice of usage. When a flue is relinedwith a material not complying with Section 2113.11.1,the chimney shall be plainly and permanently identifiedby a label attached to a wall, ceiling or other conspicu-ous location adjacent to where the connector enters thechimney. The label shall include the following messageor equivalent language: “This chimney is for use onlywith (type or category of appliance) that burns (type offuel). Do not connect other types of appliances.”

2113.11.2 Concrete and masonry chimneys formedium-heat appliances.

2113.11.2.1 General. Concrete and masonry chimneysfor medium-heat appliances shall comply with Sections2113.1 through 2113.5.

2113.11.2.2 Construction. Chimneys for medium-heatappliances shall be constructed of solid masonry unitsor of concrete with walls a minimum of 8 inches (203mm) thick, or with stone masonry a minimum of 12inches (305 mm) thick.

2113.11.2.3 Lining. Concrete and masonry chimneysshall be lined with an approved medium-duty refrac-tory brick a minimum of 41/2 inches (114 mm) thicklaid on the 41/2-inch bed (114 mm) in an approvedmedium-duty refractory mortar. The lining shall start 2feet (610 mm) or more below the lowest chimney con-nector entrance. Chimneys terminating 25 feet (7620mm) or less above a chimney connector entrance shallbe lined to the top.

2113.11.2.4 Multiple passageway. Concrete andmasonry chimneys containing more than one passage-way shall have the liners separated by a minimum 4-inch-thick (102 mm) concrete or solid masonry wall.

2113.11.2.5 Termination height. Concrete andmasonry chimneys for medium-heat appliances shallextend a minimum of 10 feet (3048 mm) higher thanany portion of any building within 25 feet (7620 mm).

2113.11.2.6 Clearance. A minimum clearance of 4inches (102 mm) shall be provided between the exteriorsurfaces of a concrete or masonry chimney formedium-heat appliances and combustible material.

2113.11.3 Concrete and masonry chimneys for high-heat appliances.

2113.11.3.1 General. Concrete and masonry chimneysfor high-heat appliances shall comply with Sections2113.1 through 2113.5.

2113.11.3.2 Construction. Chimneys for high-heatappliances shall be constructed with double walls of


MASONRY


solid masonry units or of concrete, each wall to be aminimum of 8 inches (203 mm) thick with a minimumairspace of 2 inches (51 mm) between the walls.

2113.11.3.3 Lining. The inside of the interior wall shallbe lined with an approved high-duty refractory brick, aminimum of 41/2 inches (114 mm) thick laid on the 41/2-inch bed (114 mm) in an approved high-duty refractorymortar. The lining shall start at the base of the chimneyand extend continuously to the top.

2113.11.3.4 Termination height. Concrete andmasonry chimneys for high-heat appliances shallextend a minimum of 20 feet (6096 mm) higher thanany portion of any building within 50 feet (15 240mm).

2113.11.3.5 Clearance. Concrete and masonry chim-neys for high-heat appliances shall have approvedclearance from buildings and structures to preventoverheating combustible materials, permit inspectionand maintenance operations on the chimney and pre-vent danger of burns to persons.

2113.12 Clay flue lining (installation). Clay flue liners shallbe installed in accordance with ASTM C 1283 and extendfrom a point not less than 8 inches (203 mm) below the low-est inlet or, in the case of fireplaces, from the top of thesmoke chamber to a point above the enclosing walls. The lin-ing shall be carried up vertically, with a maximum slope nogreater than 30 degrees (0.52 rad) from the vertical.

Clay flue liners shall be laid in medium-duty nonwater-soluble refractory mortar conforming to ASTM C 199 withtight mortar joints left smooth on the inside and installed tomaintain an air space or insulation not to exceed the thicknessof the flue liner separating the flue liners from the interiorface of the chimney masonry walls. Flue lining shall be sup-ported on all sides. Only enough mortar shall be placed tomake the joint and hold the liners in position.

2113.13 Additional requirements.

2113.13.1 Listed materials. Listed materials used as fluelinings shall be installed in accordance with the terms oftheir listings and the manufacturer’s instructions.

2113.13.2 Space around lining. The space surrounding achimney lining system or vent installed within a masonrychimney shall not be used to vent any other appliance.

Exception: This shall not prevent the installation of aseparate flue lining in accordance with the manufac-turer’s instructions.

2113.14 Multiple flues. When two or more flues are locatedin the same chimney, masonry wythes shall be built betweenadjacent flue linings. The masonry wythes shall be at least 4inches (102 mm) thick and bonded into the walls of the chim-ney.

Exception: When venting only one appliance, two fluesare permitted to adjoin each other in the same chimney

with only the flue lining separation between them. Thejoints of the adjacent flue linings shall be staggered at least4 inches (102 mm).

2113.15 Flue area (appliance). Chimney flues shall not besmaller in area than the area of the connector from the appli-ance. Chimney flues connected to more than one applianceshall not be less than the area of the largest connector plus 50percent of the areas of additional chimney connectors.

Exceptions:

1. Chimney flues serving oil-fired appliances sized inaccordance with NFPA 31.

2. Chimney flues serving gas-fired appliances sized inaccordance with the International Fuel Gas Code.

2113.16 Flue area (masonry fireplace). Flue sizing forchimneys serving fireplaces shall be in accordance with Sec-tion 2113.16.1 or 2113.16.2.

2113.16.1 Minimum area. Round chimney flues shallhave a minimum net cross-sectional area of at least 1/12 ofthe fireplace opening. Square chimney flues shall have aminimum net cross-sectional area of at least 1/10 of the fire-place opening. Rectangular chimney flues with an aspectratio less than 2 to 1 shall have a minimum net cross-sec-tional area of at least 1/10 of the fireplace opening. Rectan-gular chimney flues with an aspect ratio of 2 to 1 or moreshall have a minimum net cross-sectional area of at least 1/8

of the fireplace opening.

2113.16.2 Determination of minimum area. The mini-mum net cross-sectional area of the flue shall be deter-mined in accordance with Figure 2113.16. A flue sizeproviding at least the equivalent net cross-sectional areashall be used. Cross-sectional areas of clay flue linings areas provided in Tables 2113.16(1) and 2113.16(2) or asprovided by the manufacturer or as measured in the field.The height of the chimney shall be measured from the fire-box floor to the top of the chimney flue.

TABLE 2113.16(1)NET CROSS-SECTIONAL AREA OF ROUND FLUE SIZESa

For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.a. Flue sizes are based on ASTM C 315.

FLUE SIZE, INSIDE DIAMETER (inches)

CROSS-SECTIONAL AREA (square inches)

6 28

7 38

8 50

10 78

103/4 90

12 113

15 176

18 254


MASONRY


TABLE 2113.16(2)NET CROSS-SECTIONAL AREA OF SQUARE

AND RECTANGULAR FLUE SIZES

For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.

2113.17 Inlet. Inlets to masonry chimneys shall enter fromthe side. Inlets shall have a thimble of fireclay, rigid refrac-tory material or metal that will prevent the connector frompulling out of the inlet or from extending beyond the wall ofthe liner.

2113.18 Masonry chimney cleanout openings. Cleanoutopenings shall be provided within 6 inches (152 mm) of thebase of each flue within every masonry chimney. The upperedge of the cleanout shall be located at least 6 inches (152mm) below the lowest chimney inlet opening. The height ofthe opening shall be at least 6 inches (152 mm). The cleanoutshall be provided with a noncombustible cover.

Exception: Chimney flues serving masonry fireplaces,where cleaning is possible through the fireplace opening.

2113.19 Chimney clearances. Any portion of a masonrychimney located in the interior of the building or within theexterior wall of the building shall have a minimum airspaceclearance to combustibles of 2 inches (51 mm). Chimneyslocated entirely outside the exterior walls of the building,including chimneys that pass through the soffit or cornice,shall have a minimum airspace clearance of 1 inch (25 mm).

FLUE SIZE, OUTSIDE NOMINAL DIMENSIONS (inches)

CROSS-SECTIONAL AREA (square inches)

4.5 × 8.5 234.5 × 13 34

8 × 8 428.5 × 8.5 498 × 12 67

8.5 × 13 7612 × 12 1028.5 × 18 10113 ×13 12712 × 16 13113 × 18 17316 × 16 18116 × 20 22218 × 18 23320 × 20 29820 × 24 33524 × 24 431

For SI: 1 inch = 25.4 mm, 1 square inch = 645 mm2

FIGURE 2113.16FLUE SIZES FOR MASONRY CHIMNEYS


MASONRY


The airspace shall not be filled, except to provide fireblock-ing in accordance with Section 2113.20.

Exceptions:

1. Masonry chimneys equipped with a chimney liningsystem listed and labeled for use in chimneys in con-tact with combustibles in accordance with UL 1777,and installed in accordance with the manufacturer’sinstructions, are permitted to have combustiblematerial in contact with their exterior surfaces.

2. Where masonry chimneys are constructed as part ofmasonry or concrete walls, combustible materialsshall not be in contact with the masonry or concretewall less than 12 inches (305 mm) from the insidesurface of the nearest flue lining.

3. Exposed combustible trim and the edges of sheath-ing materials, such as wood siding, are permitted toabut the masonry chimney sidewalls, in accordancewith Figure 2113.19, provided such combustibletrim or sheathing is a minimum of 12 inches (305mm) from the inside surface of the nearest flue lin-ing. Combustible material and trim shall not overlapthe corners of the chimney by more than 1 inch (25mm).

2113.20 Chimney fireblocking. All spaces between chim-neys and floors and ceilings through which chimneys passshall be fireblocked with noncombustible material securelyfastened in place. The fireblocking of spaces between woodjoists, beams or headers shall be self-supporting or be placedon strips of metal or metal lath laid across the spaces betweencombustible material and the chimney.

SECTION 2114EMISSION STANDARDS

[W] 2114.1 Emission standards for factory-built fire-places. New and used factory-built fireplaces shall be certi-fied and labeled in accordance with procedures and criteriaspecified in ASTM E2558 Standard Test Method for Deter-mining Particulate Matter Emission from Fires in Low MassWood-burning Fireplaces.

To certify an entire fireplace model line, the internalassembly shall be tested to determine its particulate matteremission performance. Retesting and recertifying is requiredif the design and construction specifications of the fireplacemodel line internal assembly change. Testing for certificationshall be performed by a Washington State Department ofEcology (DOE) approved and U. S. Environmental Protec-tion Agency (EPA) accredited laboratory.

2114.2 Emission standards for certified masonry and con-crete fireplaces. Masonry and concrete fireplace model linescertified to Washington State Building Code Standard 31-2prior to July 1, 2013 may retain certification if the design andconstruction specifications of the fireplace model line inter-nal assembly do not change.

FIGURE 2113.19ILLUSTRATION OF EXCEPTION THREE CHIMNEY

CLEARANCE PROVISION


seattle dpd - 2012 seattle building code, chapter 21 …pan/documents/web_informational/...masonry...

Documents