prescriptive residential wood deck construction guide€¦ · all construction and materials...

8/14/2013

Copyright © 2013 American Wood Council 1

www.awc.org

Copyright © 2013 American Wood Council. All rights reserved.

Prescriptive Residential Wood Deck Construction

Guide

John “Buddy” Showalter, P.E.Vice President, Technology TransferAmerican Wood Council

Michelle Kam-Biron, PE, SE, SECBDirector of EducationAmerican Wood Council

www.awc.org

Copyright Materials

This presentation is protected by US and International Copyright laws. Reproduction,

distribution, display and use of the presentation without written permission of the speaker is

prohibited.

© American Wood Council 2013


8/14/2013


www.awc.org

Downloads

DCA6 Deck Guidehttp://www.awc.org/publications/DCA/DCA6/DCA

6-09.pdf

DCA6 Presentationhttp://www.awc.org/pdf/DCA6-Decks-webinar-

Aug2013.pdf

3Copyright © 2013 American Wood Council

www.awc.org

Resources

Forest ProductsSociety

Wood Design Focus

http://www.forestprod.org/


8/14/2013


www.awc.org

Objectives/Outline

Identify minimum prescriptive wood deck requirements

Describe minimum material requirements for deck construction including wood members and fasteners

Discuss design requirements and resources if prescriptive limits are exceeded

Provide a deck design example

Discuss durability issues (will not be covered)

Copyright © 2013 American Wood Council5

www.awc.org

Why is this Important?

News reports on deck collapseCompiled by Dr. Frank Woeste• 66 reports from 1996-2007

• 500+ injuries• 17 deaths

• Example:• Chicago, IL - June 2003

• 13 dead• 40+ injured

“Except for hurricanes and tornadoes, more injuries may be connected to deck failures than all other wood building components and loading cases combined!”Dr. Frank Woeste, P.E.


8/14/2013


www.awc.org

DCA 6

Prescriptive Residential Wood Deck Construction Guide – Design for Code Acceptance No. 6 (DCA 6)

Primary Cooperators American Wood Council International Code Council Fairfax County Virginia


www.awc.org

DCA 6

Additional Cooperators APA-The Engineered Wood Association

National Association of Home Builders

North American Deck & Railing Association

Simpson Strong-Tie Company

Southern Forest Products Association

Southern Pine Inspection Bureau

Stairway Manufacturers’ Association

Virginia Polytechnic Institute and State University

Washington State University

WTCA-Representing the Structural Building Components Industry


8/14/2013


www.awc.org

DCA 6

Basis and Applicability 2009 International Residential Code (IRC) bracketed text shows reference to

applicable IRC sections ex. [R317 and R318].

Recommended prescriptive construction methods meet or exceed IRCminimum requirements

Provisions not included in IRC are considered good practice recommendations

Where differences exist, IRC applies Not intended to preclude use of other

construction methods or materials All construction and materials approved by

the authority having jurisdiction


www.awc.org

DCA 6 Outline


Commentary!!!

8/14/2013


www.awc.org

Minimum Requirements

Single level residential decks only

Hot tubs outside scope Does not apply for snow loads,

snow drift loads, or sliding snow loads that exceed 40 psf

Does not address wind or seismic design issues

Decks shall not be used or occupied until final inspection and approval is obtained

Alternate methods and materials approved by the building official


www.awc.org

Objectives/Outline






8/14/2013


www.awc.org


Lumber• American Lumber Standards Committee (ALSC) approved grade mark

• Naturally durable

• Redwood or Western Cedar

• Preservative treated

• American Wood Protection Association (AWPA)

• Ground contact


www.awc.org


Fasteners Nails – ASTM F 1667

• Threaded nails as stated in this document include helical (spiral) and annular (ring-shank) nails.

Screws – ANSI/ASME B18.6.1

Bolts/Lags – ANSI/ASME B18.2.1

½″ bolts and lag screws prescribed extensively Edge distance and spacing based

on diameter

Need to adjust for larger or smaller fasteners


8/14/2013


www.awc.org

Minimum Requirements Corrosion Resistance 2009 IRC R317.3

Screws, bolts, nails• Hot-dipped galvanized• Stainless• Silicon bronze• Copper

Hangers and anchors• Galvanized• Stainless

Saltwater exposure• Stainless

Other fasteners/hardware• Approved by building official

Flashing• Nominal 0.019” min.


www.awc.org


Corrosion Resistance 2009/2012 IRC

R317.3 Fasteners and connectors in contact with preservative-treated and fire-retardant-treated wood. Fasteners, including nuts and washers, and connectors in contact with preservative-treated wood and fire-retardant-treated wood shall be in accordance with this section. The coating weights for zinc-coated fasteners shall be in accordance with ASTM A 153.


8/14/2013


www.awc.org


Corrosion Resistance – 2009/2012 IRC R317.3.1 Fasteners for preservative-treated wood. Fasteners, including nuts and washers, for preservative treated wood shall be of hot-dipped, zinc-coated galvanized steel, stainless steel, silicon bronze or copper. Coating types and weights for connectors in contact with preservative-treated wood shall be in accordance with the connector manufacturer’s recommendations. In the absence of manufacturer’s recommendations, a minimum of ASTM A 653 type G185 zinc-coated galvanized steel, or equivalent, shall be used.

Exceptions:

1. One-half-inch-diameter (12.7 mm) or greater steel bolts.

2. Fasteners other than nails and timber rivets shall be permitted to be of mechanically deposited zinc-coated steel with coating weights in accordance with ASTM B 695, Class 55 minimum.

3. Plain carbon steel fasteners in SBX/DOT and zinc borate preservative-treated wood in an interior, dry environment shall be permitted.


www.awc.org

Decking

Dimension lumber (2″ nominal)

Span rated decking ALSC decking policy

Attachment 2-8d commons

2-#8 screws

Spacing 1/8″

Perpendicular or 45°

Bear on 4 joists minimum

Substitution Approved by building official


8/14/2013


www.awc.org

Joists


www.awc.org

Joists


8/14/2013


www.awc.org

Joists

• Span table development – without overhangs– 40 psf uniform live load

– 10 psf uniform dead load

– No. 2 Grade

– L/360 Deflection Limits

– Wet Service Condition


LJ

www.awc.org

Joists

• Span table development – with overhangs– 40 psf uniform live load

– 10 psf uniform dead load

– No. 2 Grade

– Wet Service Condition


LJLJ /4 LJ /4

8/14/2013


www.awc.org

Joists


• Span table development – with overhangs– L/180 cantilever deflection limit

– 220 lb. point load at the end of cantilever 220 lbs.

LJ LJ /4

www.awc.org

Joists

220 lbpoint load controls


8/14/2013


www.awc.org

Joists• AWC Online Span Calculator

– Simple spans (no cantilever)

– Uniform loads

– Wet service conditions

– Incising factor

– 18’-0” MAX (DCA 6)Free at www.awc.org

Apps – not free


www.awc.org

Joists

• Incising factor– Refractory

species

– DFL, HF, SPF

– Reduces strength and stiffness


8/14/2013


www.awc.org

Joists

Incising factor


www.awc.org

Joists

DCA6 – Southern Pine Changes

http://awc.org/publications/DCA/DCA6/DCA6‐09.pdf


8/14/2013


www.awc.org

Beams• Spans

– L/4 maximum overhang

– Splice over posts

– Joists cannot be attached to opposite sides of the same beam


www.awc.org

Beams


8/14/2013


www.awc.org

Beams




www.awc.org

Copyright © 2013 American Wood Council

Beams• Assembly

– For built-up beams

– 10d threaded or #10 wood screws

– 16″ o.c. staggered

35

8/14/2013


www.awc.org


Framing Plan

Southern Pine2 12

11

122

700

1500

10 4

62010122

25 23 23 10 24

1210

3

12

36

www.awc.org


Joist‐to‐Beam Connections

• Options– Toe-nails

– Hurricane clip

– Joist hanger

37

LJ LJ /4

LJ LJ /4

8/14/2013


www.awc.org


Joist‐to‐Beam Connections

• Joist Hangers– Capacity per Table 3A

– Galvanized

– No clips/brackets

DCA6 Addendum

38

www.awc.org


Post Requirements

• 6x6 or larger

• Max. 14′ height

• Centered on footings

• Cut ends field treated– Copper naphthenate

– [R402.1.2]

• Post-to-Beam– Notch

• 3x or 4x beam

• 2-ply beam

• Two ½″ bolts w/ washers

– Post cap• 3-ply beams

39

8/14/2013


www.awc.org


Post Requirements

• Prohibited connection– Beam to side of post

– Ensures wood-to-wood bearing

– Avoids potential issues with non-compliant fasteners

– Bolts in wet service environments have reduced capacity

40

www.awc.org


Rim Joist Requirements• Decking attachment

– #10 x 3″ min. wood screws @ 6″ o.c.

– 10d threaded nails @ 6″ o.c.

• Joist attachment– (3) #10 x 3″ min. wood screws

– (3) 10d threaded nails

41

8/14/2013


www.awc.org

Footings [R403]

• Depth > 12″ or frost line

• Soil 1,500 psf bearing capacity


www.awc.org

Footings

• Sizes– Square footings 2″ less than

round

– 1,500 psf soil bearing

– 2,500 psi concrete strength

– Coordinate thickness with anchors

• Anchor length < footing thickness


8/14/2013


www.awc.org

• Ledger board depth > deck joist depth

• Ledger board depth < rim joist depth

• Flashing with drip edge

– Corrosion resistant

Ledger Requirements [R502.2.1]


www.awc.org

45

2012 IRC

Deck Stability – Lateral Loads


8/14/2013


www.awc.org

Ledger Requirements• Ledger board to foundation wall

– Concrete or solid masonry

– ½″ approved anchors


www.awc.org

Ledger Requirements• Ledger board to foundation wall

– Hollow masonry

– ½″ approved anchors

– Grout at anchor locations


8/14/2013


www.awc.org

Ledger Requirements

48

• I-joists

– 1″ or thicker EWP band joist• OSB

• SCL including LVL

– <1″ band joist• Free standing deck

• Full plan submission

• Trusses

– 2x4 ribbon• No deck attachment

– Requirements• Standard details

• Free-standing deck

• Full plan submission

• SBCA tech note www.sbcindustry.com


www.awc.org

Prohibited Ledger Attachment• Exterior veneers

– Brick

– Masonry

– Stone

• Requires free-standing deck

Photo courtesy of John Bouldin. All rights reserved.


8/14/2013


www.awc.org

• Cantilevered floors

• Bay windows

• Requires free-standing deck

Prohibited Ledger Attachment


www.awc.org

• Virginia Tech & Washington State University

• 3 common conditions

• ½″ diameter lag screws & bolts.

• Fastener spacing values limited to:

– Deck live load of 40 psf and 10 psfdead

– Band joist lumber with G ≥ 0.42

– Composite rim board with thickness ≥ 1″ and equivalent G ≥ 0.50

– PPT deck ledger lumber with G ≥ 0.43

– Deck ledger can be incised and wet

– Proper installation including flashing

– No decay present

– No fastener corrosion

Deck Ledger Testing

Photo courtesy of Frank Woeste and Joseph Loferski. All rights reserved.


8/14/2013


www.awc.org

Ledger Board Fasteners• IRC Table R502.2.2.1 modified to include

EWP rim boards


www.awc.org

Ledger Board Fasteners

53

IRC 2012


8/14/2013


www.awc.org

Ledger Board Fasteners• Placement

– 2″ min. for top row

– 2″ min. from ends

– Staggered in 2 rows

– Bottom row depends on ledger depth

– 5″ max. between rows

• Bolts– ½″ diameter with washers

– Pilot holes

• Expansion/Adhesive Anchors– ½″ diameter with washers

– Concrete or solid masonry

– Hollow masonry with grouted cells– Embedment length per manufacturer


www.awc.org


55

IRC 2012


8/14/2013


www.awc.org


• Lag Screws– ½″ diameter with washers

– Threads in band board

– Extend ½″ beyond band board

• Lag Screw Installation– Pilot holes

• ½″ diameter in ledger

• 5/16″ diameter in band board

– Insert by turning

– Do not hammer

– Soap or lubricant

– Snug but not over-tightened


www.awc.org

Free Standing Deck• To resist vertical loads

• Located within L/4 of wall

• Deck and house footings same elevation

• Caisson minimizes excavation by basements


8/14/2013


www.awc.org

Deck Stability• Decks > 2′ above grade

– require diagonal bracing

– Attach to exterior wall

• Parallel to beam – Bolt to beam and post

• Perpendicular to beam– Bolt to post and joist or blocking


www.awc.org


• Attachment to House – Free-standing Deck– 3/8″ ext. wall

sheathing

– 16″ o.c. fasteners staggered

– Flashing over rim joist


8/14/2013


www.awc.org

Deck Stability


Brian J. Parsons, Donald A. Bender, Ph.D., P.E., J. Daniel Dolan, Ph.D., P.E., and Frank E. Woeste, Ph.D., P.E.

www.awc.org

Deck Stability

• Attachment to House – Deck Supported by Ledger– Lateral

attachment to house floor system

– 2009 IRC

– 2 locations per deck

– 1500 lb capacity


8/14/2013


www.awc.org

62

2012 IRC



www.awc.org

Guard Requirements

• Decks > 30″ above grade require guard


8/14/2013


www.awc.org

Guard Requirements

Adjacent Fixed Seating Requirement

• 36″ measurement from seat

R312.2 Height. Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 36 inches (914 mm) high measured vertically above the adjacent walking surface, adjacent fixed seating or the line connecting the leading edges of the treads.


www.awc.org

Guard Post Testing

• IBC/IRC require guard rails to resist 200 lbconcentrated load

• Tests require 2.5 safety factor per IBC

• Virginia Tech Research– Typical ½″ bolt or lag

screw connections failed

– Commercial hold down passed

Photo courtesy of Frank Woeste and Joseph Loferski. All rights reserved.


8/14/2013


www.awc.org

Guard Requirements• Minimum 4x4 post

• Bending design value > 1,100 psi– All No.2 species shown in Table 2

– CM = 0.85, Ci = 0.80, CD = 1.6


www.awc.org

Guard Requirements

• Guard Post to Rim Joist– Hold down anchors

– Minimum of two ½″ bolts


8/14/2013


www.awc.org

Stair Requirements

• Treads and Risers– 7-3/4″ rise & 10″ run

– Except where amended

– 1x risers

– Treads per Table 6

– Openings < 4″ diameter sphere


www.awc.org

Stair Requirements

• Stringers– Minimum 2x12

– Spans per Figure 28

– Intermediate landings permitted


8/14/2013


www.awc.org

Stair Requirements

71




www.awc.org

Stair Requirements

• Stringers– Cut < 18″ o.c.

– Solid < 36″ o.c.

• Treads– Sizes per Table 6

– Connections per Fig 29


8/14/2013


www.awc.org

Stair Requirements


www.awc.org

Stair Requirements

74




8/14/2013


www.awc.org

Stair Requirements

• Guard Requirements– Required if 30″ total rise

– 6′ maximum between posts

– 34″ height minimum

– Opening <6″ diameter sphere

– Openings <43/8″ for tread guards


www.awc.org

Stair Requirements

• Stringer Attachment– Hangers

• Sloped joist hanger

• Per manufacturer


8/14/2013


www.awc.org

Stair Requirements

• Handrails– Required for stairs

with 4 or more treads

– Height 34″ – 38″


www.awc.org

Stair Requirements

• Handrails– Type I: 4″ – 6¼″

perimeter

• Circular

– 1¼″ – 2″ diameter

• Noncircular

– Max. cross section 2¼″

– Type II: >6¼″ perimeter• Graspable recess


8/14/2013


www.awc.org

Stair Requirements

• Handrails– Continuous from

lowest to highest riser

– Return to guard at each end

– May be interrupted by guard at turn


www.awc.org

Stair Requirements• Stair Footings [R403]

– 12″ min. depth or frost line

– 10″ square or 12″ diameter

– 6″ thick

– 4x4 posts centered

• Bearing Block– 2x4

– 8 fasteners

• Stringer– ½″ bolts only if guard is

required

• Lighting– Top landing

– Illuminate all landings

– Light switch inside the house


8/14/2013


www.awc.org

Framing at Chimney or Bay Window

• Headers 6′ maximum span– Use 6x6 post to reduce spans to <6′

– >6′ span requires plan submission


www.awc.org

Framing at Chimney or Bay Window

• Trimmers– Triple

• 12"-16" joist spacing

• Spans > 8'-6"

– Double• 24" joist

spacing

• Spans < 8'-6"

– “a” < 3'


8/14/2013


www.awc.org

DCA 6 Commentary

83

Beam

Joist Typ.


• Background information

• Example calculations

• Alternate prescriptive provisions– Ex: Joists framing into 2 sides of the same beam

• 8′-0″ joists from opposite sides• Use 16′-0″ joist spans for equivalent tributary area

www.awc.org

Footing Design

T

R

P5.5″

B or D

Figure C12. Footing dimensions and variables.

DCA 6 Commentary

Post load:

4

L

2

L

4

L

2

L50 R BBJJ

Square footing: 1500

12R

B

Round footing: 1500

412

RD

Footing thickness: T > P; 2

5.5

DT


8/14/2013


www.awc.org

Footing Design

DCA 6 Commentary

Table C4 - additional footing diameters/thicknesses not shown in Table 4 Assumes 1,500 psf soil

bearing capacity

Assumes 2,500 psi concrete compressive strength


www.awc.org

Objectives/Outline






8/14/2013


www.awc.org

Additional Resources

2005 National Design Specification® (NDS ®) for Wood Construction Structural lumber

• Design values

• Grading rules

Column design

Beam design

Connection design

Footing design Per engineering mechanics


www.awc.org

Design ValuesStructural Lumber Classifications Dimension Lumber

Rectangular or square cross-section 2" - 4" thick and 2" or more wide

Beams and Stringers Rectangular cross-section 6" x 8" and larger Graded for strength in bending on

narrow face

Posts and Timbers Square or nearly square cross-

section 5" x 5" and larger Graded for use as posts


8/14/2013


www.awc.org

Additional Resources

2012 National Design Specification® (NDS ®) for Wood Construction Structural lumber

• Design values

• Grading rules

Column design

Beam design

Connection design

Footing design Per engineering mechanics


www.awc.org

Design Values

Structural Lumber Classifications

Dimension Lumber Rectangular or square cross-section 2" - 4" thick and 2" or more wide

Beams and Stringers Rectangular cross-section 6" x 8" and larger Graded for strength in bending on

narrow face

Posts and Timbers Square or nearly square cross-

section 5" x 5" and larger Graded for use as posts


8/14/2013


www.awc.org

Design Values

Design values are assigned to predict strength and stiffness properties to meet engineering design requirements


www.awc.org

Design Properties ‐ Bending

93

Fiber Stress in Bending Fb


8/14/2013


www.awc.org

Design Properties ‐ Compression

94

Compression Parallel to Grain Fc||


www.awc.org

Design Properties ‐ Tension

95

Tension Parallel to Grain Ft


8/14/2013


www.awc.org

Lumber Adjustment Factors

Most common adjustment factors for decks

Beams/Joists

Columns


www.awc.org

Load Duration Factors

Assumption for decks is occupancy live load


8/14/2013


www.awc.org

Load Duration Curve


www.awc.org

Size Adjustment Factor

Common for joists/beams


8/14/2013


www.awc.org

Repetitive Member Factor, Cr

2"- 4" dimension lumber

24" o.c. or less

3 or more members

Load distributing element

Applies to Fb

For decks: Joists

Built-up beams

Cr = 1.15


www.awc.org

Wet Service Factor, CM

• Note the adjustment is unity if:

FbCF < 1150 psi


8/14/2013


www.awc.org

Incising Factor, Ci Sawn Lumber -

Refractory Species

Increase Preservative Penetration

0.4" Depth

3/8" Length

1100 teeth / ft2

density


www.awc.org

Incising Factor, Ci


8/14/2013


www.awc.org

Adjustment Factors ‐ Example

No. 2 grade, 2x8 Hem Fir deck joist, 16" o.c., incised, wet use, tabulated Fb = 850 psi CF = 1.2 CM = 1.0 Ci = 0.80 Cr = 1.15

Allowable Fb' is:850(1.2)(1.0)(0.80)(1.15) = 938 psi

Used to calculate joist spans


www.awc.org

Column Design

Columns and posts must be designed for stability and load carrying capacity Tributary area Floor/deck load Column or post length (height)

Design of solid columns with unbraced lengths in either the strong or weak axis requires buckling analysis in accordance with NDS 3.7


8/14/2013


www.awc.org

Post Height for DCA 6

6x6 minimum

4x4 Alternate DCA 6 Commentary

Southern pine – 10' max.

Other species – 8' max.


www.awc.org

Beam/Joist Design

Beam/Joist Spans are based on: Species and grade of lumber Cross-sectional size of beam Tributary load it supports

Design Considerations Bending Shear Deflection Bearing


8/14/2013


www.awc.org

Joist/Beam Design ‐ Notches

Notching Provisions – Sawn Lumber NDS 3.2.3 & R502.8

OUTER THIRD OF SPAN ONLY

1/3 JOISTDEPTH, MAX.

DEPTH, MAX. 1/4 JOIST

1/6 JOISTDEPTH, MAX.


www.awc.org

Column and Beam Design

Tables simplify process

Wood Structural Design Data (WSDD) Column load tables

Beam load tables

Requires adjusted design values

Free at www.awc.org


8/14/2013


www.awc.org

Column and Beam Design

Tables simplify process

Wood Structural Design Data (WSDD) Column load tables

Beam load tables

Requires adjusted design values

Free at www.awc.org


www.awc.org

Span Tables for Joists and Rafters Floors, ceilings, rafters Loads

Dead loads - 5, 10, & 20 psf Live loads - 20, 30, 40, 50, & 60 psf Deflection criteria

• L/180, L/240, & L/360• Adjustment factors for L/480 & L/600

Design value adjustments Size factor Repetitive member Load duration Wet service Incising

Free at www.awc.org Span table tutorial

http://www.awc.org/technical/spantables/tutorial.html


8/14/2013


www.awc.org

Span Calculator

• AWC Online Span Calculator– Simple spans (no cantilever)

– Uniform loads

– Wet service conditions

– Incising factor


www.awc.org

Connection Design

• NDS design values– Equations

– Tables

– Penetration

– Spacing, end, and edge distance

– Tension perpendicular to grain

• Materials– Wood to wood

– Wood to steel

– Wood to concrete


8/14/2013


www.awc.org

NDS Capacity Tables


www.awc.org

NDS Connection Calculator

• Single fasteners

• All 6 yield modes

• ASD and LRFD

• Free at www.awc.org


8/14/2013


www.awc.org

Spacing, End, & Edge Distances

Parallel to Grain


www.awc.org

Spacing, End, & Edge Distances

Perpendicular to Grain


8/14/2013


www.awc.org

Connecting Wood

wood and tension perpendicular to grain the evil of wood connections

initiators:• notches• large diameter fasteners• hanging loads• shrinkage


www.awc.org

Tension Perpendicular to Grain

These are no‐no’s!


8/14/2013


www.awc.org

Saturated

19% MC

Dry

CM 0.4 Lateral load (D>1/4″)

fabrication MCin-service MC

CM = 1.0 if:

1 fastener

2+ fasteners

split splice plates

Wet Service Factor, CM


www.awc.org

Objectives/Outline






8/14/2013


www.awc.org

Deck Design Example 1 Deck height = 2'-0" 8' x 12' deck surface Structural members: southern pine Decking: 5/4 radius edge southern

pine decking 48" frost line

Determine sizes for joists, beams, hangers, footings, stringers, and treads

Determine fastener spacing for lag screws in southern pine house rim board

HouseDeck


Joists

Beam

www.awc.org

Deck Design Example 1

Joist Size for 8′ span dimension (w/out overhang) DCA 6 Table 2

2x8 @ 24″ o.c.

Cantilever has same max span


8/14/2013


www.awc.org

Deck Design Example 1 Beam Size for 12′ span dimension

DCA 6 Table 3 For 8′ joist span Try 2-2x8: spans 7′-7″ LB/4 = 7′-7″ /4 = 1′-10¾″ 7′-7″ + 1′-10¾″ + 1′-10¾″ = 11′-4½″ < 12’ NG

Try 3-2x8: spans 9′-6″ LB/4 = 9′-6″ /4 = 2′-4½″ 9′-6″ + 2′-4½″ + 2′-4½″ =

14’-3” > 12” OK Use 8′ span with 2′

overhangs at each end*2‐2x10 also works


www.awc.org


Joist Hanger Size DCA 6 Table 3A

For 2x8

500 lb joist hanger


8/14/2013


www.awc.org


Footing Size DCA 6 Table 4 Thickness = 6″ Square = 15″ Round = 17″ Below frost line


www.awc.org


Ledger Fastener Spacing Assume 2x10 southern pine house rim board

Assume 2x8 southern pine ledger

DCA 6 Table 5

½″ lag screws @ 18″ o.c.


8/14/2013


www.awc.org


Stair Stringers DCA 6 Figure 28

2′ deck height

Requires 2′-6″ cut stringer span assuming 7¾″ rise and 10″ run 6’-0” > 2’-6” ok

Use a Cut stringer


www.awc.org


Stair Treads DCA 6 Table 6

Cut stringer

5/4x6 southern pine treads


8/14/2013


www.awc.org

Deck Design Example 1 Guard requirements

Deck height < 30″

Guard optional


www.awc.org

Southern Pine2 8

18

500

N/A

2 6

65/4

0882

17 15 15 6 48

80

0

8

N/A

N/A

Deck Design Ex. #1 ‐ Framing Plan

2’2’


8/14/2013


www.awc.org

Deck Design Example 2 Deck height = 8'-0" 16' x 20' deck surface Structural members: southern pine Decking: 5/4 radius edge southern

pine decking Framing around a 5′ wide by 2½′

deep bay window 48" frost line


Determine fastener spacing for bolts in 1-1/8″ EWP house rim board

HouseDeck


Joists

Beam

www.awc.org

Deck Design Example 2 Joist Size for 16′ span dimension

DCA 6 Table 2

2x10 @ 16″ o.c.

Cantilever = LJ/4• 14′-0″ /4 = 3′-6″

• 14′ + 3′-6″ =17′-6″ > 16’ OK


8/14/2013


www.awc.org


Beam Size for 20′ span dimension DCA 6 Table 3 For 14′ joist span 2-2x12 spans 8′-0″ 6x6 posts @ 8′ o.c. LB/4 = 8′/4 = 2′

overhangs 8′ + 8′ + 2′ + 2′ = 20′

OK


www.awc.org



For 2x10

600 lb joist hanger


8/14/2013


www.awc.org




www.awc.org


Ledger Fastener Spacing Assume 1-1/8″ EWP house rim board

Assume 2x10 southern pine ledger

DCA 6 Table 5

½″ bolts @ 12″ o.c.


8/14/2013


www.awc.org


Stair Stringers DCA 6 Figure 28

8′ deck height

Requires 10′-4″ stringer span assuming 7-3/4″ rise and 10″ run 13’3” > 10’-4” solid stringer

Use solid stringer

Note: cut stringers could be used with intermediate support


www.awc.org



Solid stringer

2x8 southern pine treads

Note 5/4 treads could be used if a cut stringer is included between solid stringers


8/14/2013


www.awc.org

Deck Design Example 2 Bay Window

Header = 6′

a = 2’-6”

Double trimmer joist

Trimmer hanger = 1,400 lbs


www.awc.org


Lateral attachment


8/14/2013


www.awc.org

Southern Pine2 10

12

2

600

1400

10 4

8208122

20 18 18 8 48

140

2’6”10

Deck Design Ex. #2 ‐ Framing Plan2’

2’ 2’

10

1-1/8” house rim

8’8’


www.awc.org


Deck height = 14'-0" 24' x 30' deck surface Structural members: southern pine Decking: 5/4 radius edge southern

pine decking Framing around a 8′ wide by 3′ deep

bay window 48" frost line


Determine fastener spacing for bolts in southern pine house rim board


HouseDeck

Joists

Beam

Beam

8/14/2013


www.awc.org

Deck Design Example 3 Joist Size for 24′ span

dimension DCA 6 Table 2 2x12 @ 12″ o.c. Cantilever = LJ/4

• 18′ /4 = 4′-6″• 18′ + 4′-6″ = 22′-6″ < 24’ NG

Cantilever both ends• Free-standing deck• 18′ + 3′ + 3′ = 24’ or• 16′ + 4′ + 4′ = 24’


www.awc.org

Deck Design Example 3 Beam Size for 30′ span dimension

DCA 6 Table 3 - LJ/4 = 2′-2.5″ For 18′ joist span - 3(8′-10″) + 2(2′-2.5″) = 30′-11″ OK 3-2x12 spans 8′-10″ - Use 1′-9″ overhangs each end 6x6 posts @ 8′ o.c.


8/14/2013


www.awc.org



For 2x12

700 lb joist hanger


www.awc.org



Since deck height is 14′, footing top needs to be at ground level (see Figure 22)

48″ tall caisson


8/14/2013


www.awc.org



Attachment to house

Free-standing deck DCA 6 Figure 23

½″ lag screws @ 16″ o.c. staggered

www.awc.org


Stair Stringers DCA 6 Figure 28 14′ deck height Requires 18′-4″ stringer

span assuming 7-3/4″ rise and 10″ run

NG

Requires intermediate support

• Landing• 4x4 posts


8/14/2013


www.awc.org



Solid stringer

2x8 southern pine treads

Note 5/4 treads could be used if a cut stringer is included between solid stringers


www.awc.org


Bay Window Free-standing deck

No trimmers or headers needed


8/14/2013


www.awc.org


Lateral attachment Not required for free-

standing deck


www.awc.org

Deck Design Ex. #3 ‐ Framing Plan

supportedN/A

Southern Pine

16

700

N/A

18 4

82108122

25 23 23 10 48

180

3

12

N/A

3’

3’

Supported

See figure 23

staggered

8’10’’ 8’10’’8’10’’

154

1’9’’1’9’’


beam

8/14/2013


www.awc.org

Resources

DCA6 Deck Guidehttp://www.awc.org/publications/DCA/DCA6/DCA

6-09.pdf

DCA6 Presentationhttp://www.awc.org/pdf/DCA6-Decks-webinar-

Aug2013.pdf


www.awc.org

Resources

Forest ProductsSociety

Wood Design Focus

http://www.forestprod.org/


8/14/2013


www.awc.org

Downloads

AWC DCA6 Deck Guidehttp://www.awc.org/publications/DCA/DCA6/DCA6-09.pdf

AWC DCA6 Presentation

http://www.awc.org/pdf/DCA6-Decks-webinar-Aug2013.pdf

AWC DCA6 One-Pager to Post to Website

http://www.awc.org/pdf/DCA6-ResidentialDeckGuide-1009-onepager.pdf

Forest Products Society - Wood Design Focus

http://www.forestprod.org


www.awc.org

Questions

?www.awc.org

[email protected]

202-463-2766


prescriptive residential wood deck construction guide€¦ · all construction and materials...

Documents