st monica 2007 structural inspection - alberta.ca · 2008-05-16 · st. monica catholic school...

St. Monica Catholic School

2007 Structural Inspection

Prepared for:

Edmonton Catholic Schools

Facilities Services

10734 – 120 Street

Edmonton, Alberta T5H 3P7

Mr. Mike Pieters

Prepared by:

Read Jones Christoffersen Ltd.

Suite 100, 14904 123rd Avenue Edmonton, Alberta T5V 1B4

Mr. Nick Trovato, M.Eng., P.Eng.

Managing Principal

Building Science and Restoration

March 2007

RJC No.: 30233-03

March 2007 St. Monica Catholic School 2007 Structural Inspection RJC No.: 30233-03

TABLE OF CONTENTS

1 .0 TERMS OF REFERENCE

2.0 DESCRIPTION AND HISTORY OF THE BUILDING

3.0 CONDITION SURVEY

3.1 Exter ior Masonr y Block Wal ls

3.2 Inter ior Masonr y Block Wal ls

3. 3 Roof Structure

3.4 S lab on Grade and Foundat ions

3.5 Subsur face Invest igat ion

3.6 Mon i tor ing of B lock Wal l Cracks

3.7 Non-Structura l Comments

4.0 RECOMMENDATIONS

Append ix A : Photographs


March 2007 Page 1St. Monica Catholic School 2007 Structural Inspection RJC No.: 30233-03

1 .0 TERMS OF REFERENCE

At the request of Mr. Mike Pieters of Edmonton Catholic School Board (ECSB), Read Jones

Christoffersen Ltd. (RJC) completed an investigation of the structure of the St. Monica Catholic

School located at 14710 – 53 Avenue, Edmonton, Alberta. This investigation was in response to

the concerns with movement and damage to the building structure. During our inspection, we

also examined the building envelope to provide some preliminary comments on the general

condition of the building exterior cladding.

2.0 DESCRIPTION AND HISTORY OF THE BUILDING

The single storey school building was constructed in 1973 and contains classrooms, offices and a

gymnasium. Presently the building is being used in the Edmonton Catholic School System.

In the fall of 1993, RJC performed a visual inspection of the St. Monica School to determine

whether there were any visible signs of structural distress. The building was found to be

structurally acceptable and safe to occupy, however, a number of recommendations for

monitoring and further investigation were presented to the ECSB in our report dated October

1993. In 1995 RJC performed a second visual inspection of the school in response to the

recommendations for further review of the various components. A subsurface investigation of

the slab on grade and supporting material was also performed. We are not aware of any

subsequent monitoring being performed.

The building is constructed as follows:

Roof Structure: Metal deck supported by open web steel joists and steel beams.

Vertical Elements: Load bearing masonry block walls at perimeters and portions of

the central area.

Steel tube columns in portions of central area.

Floor Slab: Four inch concrete slab on grade with slab thickened under non-

load bearing interior block walls.

Foundations: Grade beams on straight shaft concrete piles.

3.0 CONDITION SURVEY

Our 2007 investigation consisted of a visual review of the exterior elements and a general walk-

through of the interior of the school to identify prior cracks and any new occurrences of

structural damage. Photographs obtained during our inspection are provided in Appendix A.

3. 1 Exter ior Masonr y Block Wal ls

The exterior walls consist of a combination of 8” and 10” standard block units and 8” “split faced”

or textured blocks placed in stack bond.



The north and south walls of the building support the roof joists. The east and west exterior walls

of the building support a small portion (approximately 3’–9” wide strip of roof deck). The wall

elevations are shown in photos 1 to 4. It is our understanding that the exterior of the building has

been painted since our last inspection in 1995. It is unknown what type of paint was used.

Our inspections determined that the exterior of the building exhibited localized signs of

horizontal and vertical cracking in the block walls however, the structural integrity of the building

did not appear to be significantly affected at this time. The cracking observed is summarized as

follows:

.1 All the cracks identified in the 1993 report were re-confirmed with the exception of the

southwest corner (where stucco cladding was placed over the exterior wall face) and

small cracks that had been painted over. The stucco cladding was applied in

approximately the mid 1990’s, covering the original cracks. Since the re-cladding, a new

vertical crack has occurred at the southeast corner (Photo 5) confirming additional

movement of the exterior walls.

.2 In close proximity to the southwest corner is a wide crack located in the inside of the

exterior west wall (Photo 6). This crack appears to have increased approximately 8 mm

in width since our 1993 inspection. The cause of this added movement is discussed in

Item 3.5, “Subsurface Investigation”.

.3 Minor cracking was evident adjacent to the doors and window openings. In some cases,

the crack extended completely through the wall joint. Stresses are generally increased in

a wall around openings therefore cracking is anticipated at these locations (Photo 7).

.4 Additional minor cracking was evident at the northwest and northeast corners of the

building (Photo 8) including an area on the south elevation adjacent to the far east

window. A horizontal crack was also identified on the interior surface of the exterior wall

at the same far east window location. Crack widths did not appear to be significant

however in some cases, the crack extended completely through the wall joint.

.5 The block walls around the gymnasium area have a stucco finish to the exterior. The

finish generally appeared to be in good conditions except for two small horizontal cracks

on the south elevation and stucco delaminations at the base of the west wall and higher

up on the south wall (Photo 9 and 10). The damage at the base of the wall could be due

to vertical movement of the sidewalk or from damage during snow removal. The cause

of the damage at the upper portion of the wall is not known and a more detailed building

envelope investigation is required to determine the cause of the damage noted.

.6 There is a lack of control joints in the exterior block walls. This may result in cracking of

the wall due to expansion and contraction of the block due to changes in temperature.



3.2 Inter ior Masonr y Block Wal ls

Both load bearing and non-load bearing block walls are provided inside the school. The load

bearing walls use 8” wide block units and are in the east-west direction. These walls are

generally in good condition with very little cracking evident.

The non-load bearing walls use both 6” and 8” wide block units and are typically in the north-

south direction. These walls are used to separate the classrooms, office, and storage and

washroom areas. Cracking was evident in a number of locations throughout the building (Photos

11, 12, and 13). Photos 11 and 13 show the cracks identified in the 1993 report that were

subsequently caulked. The failure in the caulking may indicate that additional movement of the

interior wall or that the caulk may have debonded from the substrate due to an incorrect surface

preparation or application. There appears to be little or no change in the size of the cracks

observed.

3.3 Roof Structure

Ceiling tile was installed in the majority of the building therefore the roof structure could not be

totally examined. Selected ceiling tiles were removed in a number of areas to review the

condition of the roof structure. There was also considerable obstruction with mechanical ducting

and piping in the ceiling space.

In general, the roof structure appeared to be in good condition. There were no signs of

overstressing evident in the roof deck or the supporting joists and beams (Photo 14).

The roof deck and joists in the gymnasium area were totally exposed and appeared to be in good

condition (Photo 15).

Steel angles are provided along the east and west perimeter block walls to support the metal roof

deck. Generally, the angles were in good condition and fastened to the block wall with embedded

bolts. In one location (staff room, west wall), several nuts used to anchor the angle were not

tightened. This condition was identified in both RJC’s 1993 and 1995 report. A steel bracket at

the same location was not fastened to the block wall (Photo 6).

3.4 S lab on Grade and Foundat ions

Our inspection of the gymnasium floor noted the following:

.1 The floor is now surfaced with vinyl tiles.

.2 On the northwest portion of the gym floor, a floor crack parallel to the west wall was

identified and the floor slopes outward toward the wall from the crack.

.3 A floor crack was identified in the southwest corner of the gym extending from the west

wall to approximately three feet from the south wall where it then runs east. The floor in

this area also sloped downward from the crack to the exterior wall.

Cracks were noted in the washrooms and office in the southwest corner of the school



Slab cracks were noted in the southeast entrance, the south entrance and the west entrance to

the building. Vertical movement of the slab was evident in the southeast corner of the building

(Photo 16). Cracking and vertical movement was also evident at the south entrance to the school.

Much of the remaining floor slabs were overlaid with carpet therefore direct inspection of the

concrete slab in these areas could not be performed.

The cracks noted are not of structural concern and do not affect the structural integrity of the

floor slabs. These cracks appear to be likely caused by movement of the slab on grade and may

be due to settlement of the underlying soil. This is discussed further in Item 3.5.

3.5 Subsur face Invest igat ion

Cracking of the exterior block walls and the non-load bearing interior block walls is primarily

evident along the south side of the building. It appears that there may have been vertical

movement of the structure in this area.

A review of the geotechnical report for this project (prepared by R.M. Hardy and Associates and

dated July 28, 1972) determined that there may have been areas on site where as much as 4 feet

of fill would be required to achieve the finished floor elevations for the slab on grade. The report

noted that if clay fill was used beneath the floor slab, some swelling of the clay could be

anticipated. Highly plastic silty clays have the potential to shrink or swell with changes in

moisture content therefore it is possible that the movement may be due to settlement of the

foundations or uplift due to swelling of the soil.

In order to examine existing soils conditions and to determine whether the soil has settled under

the slab on grade, cores were removed from the floor slab at five locations. These locations were

along the interior perimeter of the building at various areas throughout the school. Soil samples

were obtained and examined to determine the condition of the material below the slab on grade.

Testing was performed by HBT Agra Limited.

Their testing determined that the slab was placed on clay fill. Since the clay fill can be expected

to move with changes in moisture content, this may have resulted in the movement and cracking

of the floor slabs and block wall.

The testing also determined that at three locations, voids of ½ to 1 inch were present between the

floor slab and the sub base material. This may be due to a combination of settlement of the

compacted fill after construction of the building and/or swelling and shrinking of the soil.

It is our opinion that the slab-on-grade cracking relates to the soil conditions encountered on site.

The movement noted does not appear to be excessive and does not appear to pose a structural

concern.

If desired, the sub base conditions under the slab on grade can be monitored to determine if

water is penetrating the soil and possibly causing some of the movement in the building. The

core holes provided during the test program have been covered with a removable grating. These



covers can be removed and checked for moisture in the holes by RJC or by the Building

Maintenance staff. Data could be recorded over a one or two-year period at three-month

intervals to determine if water is evident in the sub base. If water is evident, an appropriate

repair method could be determined to try to control the moisture under the slab.

3.6 Mon i tor ing of B lock Wal l Cracks

The 1993 inspection determined that the building exhibited localized signs of horizontal and

vertical cracking in the exterior and interior block walls. In general, the structural integrity of the

building did not appear to have been significantly affected by this cracking. It was recommended

that the crack widths be monitored to determine whether there was ongoing movement in the

structure.

In December 1993, crack widths were measured at twelve locations throughout the school. These

locations were recorded on site and monitored to determine whether there was any noticeable

change in these cracks. Crack widths were measured for a two-year period.

During the monitoring there was no significant movement recorded. In general, the change in

crack widths was less than 1 mm.

At the time of this inspection, one of the cracks identified in 1993 and 1995 had increased in size

by 8 mm (staff room). The appearance of the new crack on the southeast corner may indicate

that this portion of the school may be experiencing more movement compared to the rest of the

building.

In 1994, a number of cracks were sealed by ECSB staff with a flexible caulking and then walls

painted. Generally, these repairs are performing as intended with some added movement

apparent at selected areas (Photos 11 and13).

Isolated areas were observed where the caulking was not fully bonded to the block (Photo 17).

This was primarily in the meter room area in the southeast corner and in the bathrooms off the

main entrance of the school (Photos 11 and 13). It appears that there may be some movement in

this area or that the joints may not have been adequately prepared or filled with caulking at the

time of application.

Based on our inspection and monitoring of selected cracks in the structure, it appears that the

ongoing movement in the building is minimal and that the structure’s load carrying capacity has

not been significantly affected.

The structure will continue to undergo movement due to thermal changes and fluctuations in the

moisture content in the soil around the building. We do not anticipate that this movement will be

very significant however; it is recommended that an annual inspection of the structure be

performed to determine whether new cracks have formed or existing cracks have increased in

size. It is recommended that the joints in the meter room and any other wide cracks in the

exterior walls be cleaned and caulked. This will permit easy inspection and monitoring of future

movements in the structure.



3.7 Non-Structura l Comments

Although our inspection was limited to the structural components of the building, the following

non-structural items are noted for your review.

.1 Roofing

Water stained ceiling tile was evident in isolated areas (Photo 18). These stains may be

caused by leaks in the roof, water penetration through the exterior wall, or leaky mechanical

components located above the ceiling tiles. Further investigation is required to determine

the exact cause of the stains. The roof was not inspected during this investigation due to it

being covered with snow. It is recommended that the roofing be inspected by a qualified

roofing inspector once the snow has melted.

.2 Building Envelope

The building envelope physically separates the exterior environment from the interior

environment. In this case , it includes the block walls, the windows and doors, and the roof.

The following comments are offered:

1. Several cracks in the exterior walls were identified. These cracks could allow air and

water to enter the block wall causing deterioration of the block. Air loss through

these cracks is also expected, creating greater loads on the building heating system.

It is recommended that the direct water penetration and air infiltration be addressed

by sealing all cracks with a flexible sealant.

2. Staining and powdery deposits (efflorescence) were noted on the interior surfaces of

the exterior block walls (Photos 19, 20, and 21). It appears that the walls are poorly

insulated and that moisture is entering the block either through leakage at the roof

level, direct penetrations through the exterior block face, or as a result of

condensation. Although this presently does not pose a structural problem,

continued exposure to moisture may deteriorate the block and interior finishes.

The condensation problem would require further investigation. The ECSB may

consider performing an assessment of the building envelope and roofing system to

determine cost-effective methods to improve the energy efficiency of the building

and reduce water infiltration onto the structure.

3. The windows consist of manually glazed sealed units in aluminum frames with

spandrel panels at the top and awning style vents below. Air infiltration was

observed during smoke tests on selected windows and doors (Photo 22). The

interior and exterior caulking at the perimeter of the windows appeared to be in poor

condition (Photo 22 and 23). It is recommended that the windows and doors be re-

caulked to prevent further air movement through these locations. Yearly inspection

and periodic replacement of weather stripping by maintenance staff is also

recommended to reduce the potential for leakage.



4.0 RECOMMENDATIONS

Based on our investigation, it appears that the structure is experiencing some movement induced

cracking of the block walls and slab-on-grade however, it is our opinion that the school is

presently safe to occupy. Our recommended work is minor in nature and could be performed as

part of building maintenance. We recommend the following:

• In general, the cracking observed does not present an immediate concern to the structural

integrity of the building. We anticipate that the building structure should perform adequately

for the life of the building however, on-going movement of the foundations and slab on grade

will likely occur. It is recommended that the building be monitored on a regular basis to

determine the extent of crack movement. We recommend that the next inspection be

performed within 2 or 3 years.

• The slab on grade movement appears to be due to the underlying soil conditions. The

cracking does not pose a structural concern. In order to reduce the risk of slab movement,

the following options could be considered:

o The floor could be stabilized by removing the slab, performing sufficient surface

preparation to the underlying soil and replacing the slab, ensuring it is anchored to the

perimeter grade beam to provide some structural support at that location.

o The floor could be removed and replaced with foundations and a structural slab on

grade.

These options are very expensive and likely not warranted for this building.

If the sloped floor identified in the gym, staff room, and meter room poses a serviceability

problem with the users of the building, consideration could be given to application of a

lightweight, self-leveling floor filler to level the surface. If future movement occurs (uplift or

settlement), the filler could be removed or additional material provided as required.

Alternatively, the floor could be raised by mud-jacking. Mud-jacking is a process where grout

is placed below the slab under sufficient pressure to fill voids and raise the slab. The risk

with this method is that if the soil swells and the slab lifts in the future, the slab will be higher

than the desired elevation. This will be difficult to correct and would require grinding or

removal of the slab.

We note that both these solutions do not address future movement and it is possible that the

slab could continue to lift or settle and that further repair would be required. Since it is

possible that the slabs may be continually moving, we would recommend that the areas be

monitored for movement prior to performing any repairs.

• The roof structure generally appeared to be in good condition. Two minor deficiencies were

noted in the southwest corner staff room. It is recommended that the loose nuts observed in

the ceiling space along the west wall be properly tightened against the deck support angle.

Also, the block along the west wall should be repaired and the anchors fastened to the roof

truss bracket.



• An inspection of the roof membrane should be performed annually to identify possible areas

of repair with the roofing membrane and flashing.

• Repair of areas where the block and stucco may be loose (such as the south-west corner) is

recommended. This work should be performed in the summer of 2007.

• Water appears to have entered the exterior block either through leakage at the roof level,

direct penetration through the exterior block face, or as a result of condensation. Although

this presently does not pose a structural problem, continued exposure to moisture may

deteriorate the block and interior finishes. Also, there is minimal insulation in the exterior

wall assembly. It is anticipated that there is considerable heat loss through the exterior walls,

thereby increasing the heating costs for this building.

It is recommended that in the short-term, the direct water penetration be addressed by

sealing all wall cracks and window joints with a flexible sealant, reviewing and repairing any

leakage at the parapet level.

If the building is to be kept in service for the long-term, consideration should be given to re-

cladding the exterior. This could include application of a waterproof coating, insulation and

new exterior cladding. We also recommend that a detailed assessment of the building

envelope be performed to determine cost-effective methods to improve the overall building

envelope.

Read Jones Christoffersen Ltd. would be pleased to assist you with the implementation of the

recommendations presented. We can assist you with the technical and administrative requirements for

this project. Our services would include the preparation of specifications and drawings for bidding of the

project, site inspection services during construction, and contract administration.

Thank you for selecting RJC for this project. Should you have any questions or comments regarding this

report, or if we may be of further service, please do not hesitate to call this office.

READ JONES CHRISTOFFERSEN LTD.

Nick Trovato, M.Eng., P.Eng.

Managing Principal

Building Science and Restoration


March 2007 St. Monica Catholic School 2007 Structural Inspection RJC No.: 30233-03

APPENDIX A

Photographs


March 2007 Page A-1St. Monica Catholic School 2007 Structural Inspection RJC No.: 30233-03

Photo 1: South Elevation

Photo 2: North Elevation



Photo 3: East Elevation

Photo 4: Partial West Elevation



Photo 5 Southwest corner.

Photo 6: Crack in West wall (staff room).



Photo 7: Cracks above window (window not shown) - East elevation.

Photo 8: Northeast corner.



Photo 9: South wall of gym stucco delaminations.

Photo 10: Delaminations repaired at the base of the gym west wall.



Photo 11: Interior wall crack filled with caulking.

Photo 12: Storage room crack, west facing.



Photo 13: Bathroom adjacent to main entrance.

Photo 14: Roof structure.



Photo 15: Gymnasium roof structure.

Photo 16: East entrance.



Photo 17: Meter room.

Photo 18: Water stains on ceiling tiles in gym equipment room.



Photo 19: Efflorescence on the interior surface of the exterior block walls.

Photo 20: Efflorescence and paint peeling.



Photo 21: Efflorescence on east wall in meter room.

Photo 22: Air infiltration, east wall classroom.



Photo 23: Failed caulking on exterior window frame.


st monica 2007 structural inspection - alberta.ca · 2008-05-16 · st. monica catholic school...

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