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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 14 09/30/2011
The exhaust fans and open windows should be used whenever bathing, dishwashing,
cooking, or similar activities are occurring.
Excessive condensation can damage interior surfaces and provide conditions for mould or other
fungal colonies to propagate. Some mould or fungal species are toxic to some humans. It is
beyond MAE’s area of expertise to comment on mould or fungal colonies.
During the course of our interior inspections we noted that all of the units that were inspected
have been provided with bathroom and kitchen fans.
4.5 WALLS
For the purposes of this investigation, wall assembles have been categorized into thee types –
one below grade wall assembly, and two above grade wall assemblies: stucco on steel stud
framing and mass concrete walls.
4.5.1 Stucco on Steel Stud Framing
The components that make up the stucco wall assembly are listed and shown schematically in
Figure 1 below. The schematic detail below has been reproduced from the Architectural
drawings provided for our review.
Figure 1 - Stucco Wall Assembly – Plan View
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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 15 09/30/2011
The stucco walls assemblies can be described as face-sealed assemblies. The outer face of the
stucco is the primary defense against water ingress with no provision to handle any moisture
ingress once it occurs. Historically, face sealed wall assemblies have not performed well in our
climate.
The stucco appears to be a pebble-dash stucco and dates back to the original construction period.
It should be noted that the Construction Drawings do not show the presence of building paper or
a sheathing membrane, which is typical for this type of wall assembly. The Construction
Drawings indicate that the original sheathing is a rigid mineral sheathing. While performing the
invasive testing, plywood sheathing was observed at many locations. Batt insulation along with
poly vapour barrier were also typically observed in the exploratory openings.
The paragraphs below describe some of the components that are found in the wall assemblies
followed by descriptions of the expected behavior of the above grade walls.
Wall Sheathing
The sheathing provides backing for stucco attachment and also provides lateral support for the
steel studs.
If the wall sheathing is exposed to moisture for an extended period of time it will deteriorate.
Furthermore, moisture may be able to travel through the sheathing to the underlying structural
components, causing them to deteriorate.
If the sheathing is allowed to deteriorate, the structural capacity of the steel studs, and the
fasteners that connect the stucco to the studs, can be compromised. A reduction in the structural
capacity of the studs and/or fasteners would compromise public safety. During the course of our
investigation we observed no evidence to suggest that structural integrity had been compromised.
Steel Studs
The steel studs form part of the building’s exterior walls and are not designed to carry building
loads. The studs must transfer gravity loads from the weight of the wall assemblies along with
wind and seismic loads.
Batt Insulation
The insulation reduces heat flow between the inner and outer sides of the wall assembly. The
batt insulation’s effectiveness would be reduced if it becomes water damaged.
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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 16 09/30/2011
Vapour Barrier
The vapour barrier resists the movement of water vapour through the assembly. If warm water
vapour is allowed to come into contact with colder components, such as the inside face of the
exterior sheathing, condensation could occur, which may allow liquid water to accumulate within
the hidden sections of the wall assembly. Vapour barriers are generally not required within un-
insulated wall assemblies that enclose unheated spaces.
Expected Behaviour – Stucco Walls
This is the wall’s exterior surface and it’s primary defense against water infiltration. Wire mesh
is embedded into the stucco and is mechanically fastened, through the exterior sheathing, to the
studs. The mesh fasteners must be strong enough to resist vertical, outward, and horizontal
forces that may be imparted on the wall. The mesh performs two primary functions: it controls
stucco cracking and it connects the stucco to the building’s structural components.
Stucco wall assemblies as described above are commonly referred to as a face sealed assembly.In a face sealed assembly, resistance to water penetration is controlled by the continuity of the
outer cladding. This system typically incorporates limited flashings not to direct water out of the
wall assembly but rather away from the assembly. The disadvantages of these assemblies are:
• In a face sealed assembly, in order to effectively resist water infiltration, the outer cladding
and penetrations through the outer cladding, such as windows or similar openings, must
remain watertight. In practice, complete water tightness of the outer cladding is difficult to
achieve.
• In a face sealed assembly, the addition of flashings is meant to assist in directing water away
from the wall assembly. In practice, however, the lack of a drainage plane behind the stucco
cladding traps water between the back of the cladding and the sheathing membrane. As such,
moisture behind the cladding is unable to flow down to the flashings to be directed out of the
wall assembly.
The behavior of a typical face sealed stucco clad wall is described below:
The stucco, acting like a sponge, has the ability to absorb a certain amount of water. If the
amount of water that the stucco must absorb exceeds its capacity, the excess water may be driven
inward through cracks or other breaches in the cladding. The driving force can be supplied by
wind, unbalanced inward vapour pressures that can occur if the exterior face of the wall heats up
from solar energy, or from other unbalanced air pressures. Once the moisture has migrated
through the breaches to the stucco’s inner surface, wind or other unbalanced pressures can
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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 17 09/30/2011
continue to drive the moisture to the sheathing. The exterior sheathing has a limited a capacity to
resist water damage.
If the stucco stops being wetted before its capacity to absorb water is reached, a drying process
begins whereby the stucco may be able to dry to the exterior and water ingress may desist. This
system can work provided the drying process is long enough and the wetting process is short
enough. The likelihood of water damage to vulnerable components will increase if a long wet
winter is followed by an unusually wet or cloudy summer.
Stucco, like other cementitious building materials, expands and contracts with changing ambient
temperatures and humidity levels. If appropriate allowances are not made for the
expansion/contraction forces, the stucco will crack. If the cracks are deep enough, the cracks
will breach the cladding. The expansion/contraction forces are usually accounted for by
providing appropriately spaced and detailed control joints. The control joints may be located
beside window or door openings. The British Columbia Wall and Ceiling Association, in the
1993 edition of its Stucco Resource Guide, recommends that “On walls, where the length of
stucco surface exceeds 4,500 mm provide vertical control joints not more than 3,000 mm on
centre.” It is worthy of note that the 1997 edition of the Stucco Resource Guide recommends
that “…joints be installed in framed and sheathed construction so as to create stucco panels of
approximately 14 m2 to 17 m2 in as square a configuration as possible...”
Control joints should be wide enough to accommodate the expected movement in the adjacent
stucco panels. The joints should be flexible enough to accommodate the expected expansion and
contraction of adjacent panels. The recommended style of control joint is usually “w” shaped
and accommodates movement in the materials while being fully embedded in stucco and limitingwater ingress.
4.5.2 Mass Concrete Wall
The components that make up the concrete wall assembly are listed and shown schematically in
Figure 2 on the following page. The schematic detail below has been reproduced from the
Architectural drawings provided for our review.
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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 18 09/30/2011
Figure 2 – Mass Concrete Wall Assembly – Plan View
The exposed concrete walls at Chelsea Terrace have an exterior coating applied to provide
protection from the elements. For descriptions of remaining wall assembly components, refer to
the descriptions in Section 4.5.1.
Expected Behaviour – Concrete Walls
If the concrete has not been coated with elastomeric or similar sealer, it will absorb moisture like
a sponge. Wind can drive absorbed moisture inward or outward, depending on its direction.
Heat from the sun can remove the moisture from the concrete through an evaporation process.
Mass concrete walls are generally considered to be robust especially if they are properly coated.
Moisture absorption, within reason, is not generally thought to be detrimental to the structural
capacity of the walls provided the exposed face of the concrete is maintained in good condition.
4.5.2 Below Grade Walls
The below grade wall assemblies enclose the parking garage and some areas of the suites. The
Architectural Drawings do not indicate how the below grade walls resist water ingress; however ,
typical below grade wall assemblies have some form of dampproofing.
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Building Envelope Condition Assessment for Chelsea Terrace
1040 Pacific Street, Vancouver, British Columbia
Page 19 09/30/2011
A thin bituminous damp-proof membrane appears be adhered to the exterior face of most the
concrete walls at Chelsea Terrace. The presence of a damp-proof membrane was verified at
most exposed walls, and some areas appear to have had more recent repairs performed. If
present, the membrane provides the primary resistance to water infiltration. According to the
Construction Drawings, a drainage pipe is located below the wall to collect ground water and
transport it away from the building.
In the event that there is no damp-proof membrane or that it becomes overwhelmed, the concrete
wall has the capacity to store a certain amount of moisture within its thickness before allowing
water to penetrate to the interior.
Below grade concrete wall assemblies can perform well provided that:
• The drainpipes do not become clogged. Clogged drainpipes could allow a build-up of
hydrostatic pressure;
• The damp-proofing membrane is present and does not break down. Like all building
components, the membrane has a finite reliable life expectancy. In the absence information
regarding the existing membrane, it is difficult to estimate its reliable life expectancy. A
broad estimate of the reliable service of the membrane would be 20 to 30 years;
• The interface between the above grade framing components and the below grade concrete
wall remains watertight.
4.6 WINDOWS AND DOORS
4.6.1 Windows
The exterior windows at Chelsea Terrace are double glazed, aluminum-framed assemblies. The
operable windows are predominantly sliders and some are hinged awning style. Good quality
aluminum windows should provide approximately 20 years of reliable service. Notation on the
window frames indicates that they were manufactured in 1981, thus, at 30 years of age, they
have reached their expected reliable life span.
Aluminum window frames are generally assembled from four separate extruded aluminum
components – two jamb components, one head component and one sill component. The four
components are connected together at the four corners of the assembly and sealed against water
ingress with small joint sealant (caulking). Eventually, the small joint sealant breaks down and
is no longer effective.
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Building Envelope Condition Assessment for Chelsea Terrace
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Window frames are generally flush with the exterior face of adjacent walls and are typically
surrounded by continuous stucco cladding. Photo 4 shows a typical exterior window/wall
interface. Head flashing has been installed at window heads, however the lack of end dams has
significantly reduced the effectiveness of the head flashing. Windowsill flashing was not present
at the building. A good portion of the windows are located directly beneath roof/balcony
overhangs, which provides the windows with protection from bulk water penetration.
Photo 4 – Typical windowsill/ wall interface. Photo 5 – Typical Window head and head flashing
detail.
The Architectural Drawings do not indicate how window assemblies interface with adjacent wall
assemblies. Sealant has generally been used at the window-to-wall interfaces to provide
protection against air and water infiltration. The condition of the sealant ranged from fair to
poor.
Deteriorated sealant will increase the likelihood of water infiltration and allow air to pass
through the window-to-wall interfaces. Water ingress can deteriorate interior finishes and
structural components, while the increased air flow will:
• Increase the likelihood of water infiltration;
• Reduce the building’s energy efficiency;
• Increase the likelihood of condensation on the inside face of the window assemblies, and;
• Increase the cold drafts in the vicinity of windows.
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Building Envelope Condition Assessment for Chelsea Terrace
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4.6.2 Doors
Suspended balconies and patios are accessed via aluminum framed sliding glass doors. The
majority of the sliding glass doors are located beneath roof or balcony overhangs and are thus
protected from wind driven rain. Sliding glass door details are similar to window details.
The exterior doors at Chelsea Terrace are typically metal assemblies that have been mounted inmetal frames. The overhang varied from door to door, but was generally present. The main
entrance doors are glazed storefront assemblies under a large overhang.
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Building Envelope Condition Assessment for Chelsea Terrace
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Page 22 09/30/2011
5.0 OBSERVATIONS, DISCUSSIONS, AND RECOMMENDATIONS
This section describes relevant observations and, where applicable, our recommendations to
address observed deficiencies. Time frames for implementation of the recommendations are
given. Delaying the implementation of these recommendations may, over time, increase the
magnitude of the noted deficiencies, which in turn will increase the eventual cost of implementation.
Each recommendation is presented with an order of magnitude budget, which has been derived
from our perusal of the Construction Drawings and our experience with similar projects.
It is difficult to provide an accurate cost estimate without some preliminary design work and a
clearly defined scope of work. The actual cost of the work cannot be known until material
quantities have been reliably estimated, project drawings and specifications have been produced,
contractors have bid on the project, and the extent of any hidden damage is known.
Where applicable, budget values account for consulting fees, taxes, and contingency for hidden
damages, but do not account for inflation.
5.1 OCCUPANT SURVEY
All of the completed occupant surveys have been reproduced in Appendix C. A summary of the
survey results is presented in Table 4.
Table 4 – Occupant Survey Results
Total number of units at Chelsea Terrace: 112
Total number of units that responded to the survey: 57 (51%)
ANALYZED DATA
# of
Responses
% of Units That
Responded
% of Total #
of Units
Units reporting signs of interior water stains 19 33% 17%
Possible water leaks 7 12% 6%
Probable window condensation 14 25% 13%
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Building Envelope Condition Assessment for Chelsea Terrace
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Page 23 09/30/2011
A review of Table 4 and the raw data that is presented in Appendix C indicates that one third of
the collected surveys report some evidence of leakage or condensation, which is 17 percent of
the total units in the building.
5.2 ROOFS
The low-slope roofs will be divided into two categories for this report: the main roofs and the
lower tier roofs. The roofs are comprised of SBS sheet membrane over a concrete substrate.
The main roof will include the large roof above the ninth level (including the mechanical room
roofs), the roof above the eighth level (west side and southeast corner), and the roof above the
fifth level (west side). The lower tier roofs will include all the smaller roofs projecting from the
building. Refer to Drawing A2 for the roof plan.
The main roofs appear are roughly 14 years old. A good quality 2-ply SBS roof membrane that
has been properly maintained should provide 20 years of effective service. The roofs are
generally in good condition for their age. Refer to Photo 6. The roofs cover the majority of the
building and have few mechanical penetrations compared to their size, which provides a simple
roof configuration and drainage plan. No leaks were reported from the main roofs during our
investigation.
Photo 6 – Main roof above ninth level. Photo 7 – Roof penetration detail on upper
mechanical roof required some maintenance.
The main roofs should receive regular maintenance to ensure they reach their expected service
life. It was noted that some SBS cap sheet is beginning to delaminate at the seams of some
penetrations, which should be addressed as a maintenance item. Refer to Photo 7. Additionally,
a patio furniture set was observed set up on the roof above the eighth level, west side. Refer to
Photo 8. The roof membrane is not designed to accommodate such point loads and foot traffic