Following The American Psychological Association’s Guidelines
Most buildings once completed take at least one year to settle and require repairs and maintenance. However, many older multiple dwelling buildings have suffered unforeseen issues. The most common problem is water ingress through the building envelope. The reason why residential buildings are critical and require closer and immediate attention is because these buildings belong to people who have invested their life savings into them for comfort and spend most of their time in those places. Commercial and industrial buildings do not require as much attention and their environmental separation requirements vary because they are only occupied by non-residents for the most part. However a residential building can become more complicated due to changes code and material requirements. Unfortunately, no wall system is completely resolvable. It can only be designed for better performance to improve upon environmental separation between the interior and exterior.
This paper describes an envelope repair situation to a typical multiple residential building experiencing long-term water ingress. Besides the material and the work performed, it outlines the duties of the contractors, sub-trades, consultants, and insurance providers for further clarity of the project. Although the work, applications, and materials mentioned may be deemed to resolve the issue, they are merely only examples of products and procedures selected by a consultant and acceptable in a particular climate for envelope repairs. Bear in mind that code requirements and products vary in different climates and geographical locations, and therefore shall not be used in practical applications or pertain to a particular building or address, as this paper is for the purposes of information and a class presentation for the layperson to understand only. Many sections of this paper are arranged to appear in a specification and instructional form of work for each aspect of the building being repaired. Examples of photographs provided are only to illustrate results of water damage to typical assemblies, and throughout the report they are explained in steps to reinforce an exterior wall system to solve water ingress problems.
For further clarity, at the end of the written report, a section explaining the timeline and progress of the work is added under Section 11.0. as implying each step within the specification section would be too complicated.
Keywords: building envelope repairs, water ingress, environmental separation, exterior wall cladding systems, moisture/vapor barriers, stucco wall damage
- Project Summary
The project consists of building envelope repairs and upgrades to a building known as Sunwater Dwellings, a multiple dwelling low-rise building (four storeys). The building is strata-titled and property management has filed together agreements from all strata members in the building who wish to see the building undergo rightful repairs and exterior wall remediation to bring the building up to the provinces latest code requirements.
The building, according to the architectural drawings, was constructed in 1989. It is constructed of wood-framed, combustible construction over a cast-in place concrete perimeter and underground parking garage. Since the building contains a fair amount of combustible elements, the building has a sprinkler system installed as was required at the time of construction as stated in the by-law. The existing cladding mostly consists of face-sealed stucco with a smaller percentage of wood-panel siding at the bay window walls. The windows are aluminum frames with double-glazed units. The existing balconies are covered with poly-vinyl chloride (PVC) cap sheeting on the surface. The existing 4th floor deck waterproofing is comprised of a built-up roofing system with wooden deck boards over top.
2.0 Scope of Work
Prior to any work initiated, a detailed assessment revolving about the building is required to determine the extent of the repairs and to determine which professionals are required and suitable for the task. The building strata requested a licensed contractor, specialists in building envelopes, to carry out a building envelope condition assessment (BECA) at the Sunwater Dwellings residential project. The intent of the assessment is to first investigate the building envelope assemblies and their general conditions in order to conform to the current building code. Some elements of the current assemblies shall require replacements of their component parts or replaced with new products depending on the condition of components and whether the code permits the use and application of existing components to be replaced. The following descriptions will provide reasons for conducting the remedial work:
- Whether signs of problems at recent balcony renovations and other isolated problems continue to occur on a more widespread basis at other balconies and decks.
- What renovation strategies may be required to ensure the long-term performance of the balconies and decks, given the problems already uncovered during a recent site investigation.
- Whether any unknown concerns exist at other building envelope assemblies such as cladding, windows, and doors that may warrant higher priority renewals or that may impact on the work recommended at the balconies and decks, and
- How the strata may best manage or stage the long-term renewals of the remaining building envelope systems for cladding components, and where their current state is such that immediate repairs or renovations are not necessary.
- Exterior Walls
- Windows and Doors
- Balcony Decks
- At-Grade Waterproofing Assemblies
2.2 Exterior Walls
Where the base of the walls intersecting onto the roofs were opened up, and a series of openings made during the investigation, the east elevation seems to be significantly affected by water and moisture retention resulting in deterioration to the structure. The remaining elevations visually appear to be in a generally dry and stable state. However, during the construction of the building the vapour barriers were applied closer to the cold side of the exterior wall. This implies in the years to come, water moisture will continue to build up and cause dry rot, prompting a second wave of repairs. Only during the work in progress stage will the internal conditions of the walls be determined. Where the stucco cladding meets the balconies are significantly deteriorated due to water ingress at poorly constructed column intersections and at parapet flashing intersections. These conditions have also affected isolated wall section around and below balconies and decks.
Though the rest of the building walls appear stable because of their bearings around the building, they do show signs of varying degrees of withering and distress common to buildings of this age, plus the orientation of the vapour barrier. Various components such as openings around the windows and doors show trails of water ingress into the walls from these openings.
2.3 Windows and Doors
2.4 Balcony Decks
The parapet walls and columns that enclose the balconies and decks are significantly damaged at most balconies and decks. Additionally, the through-wall scupper drains are poorly detailed and allowing water seepage to occur at the front face of the balconies. The existing waterproofing membrane is a state of aged fatigue that it can no longer be reasonably salvaged without replacement. Based on the combination of these components, the general state of the balconies and decks is in poor condition with withering to the structure occurring on a fairly widespread basis.
The flat roof and pitched roof systems have not been replaced since the building was first built. The mainframe of the roof itself is in fairly good condition, but the perimeter where it meets the exterior walls need to tie in with the proposed exterior wall cladding along with new membrane. The eyebrow roofs at various areas of the building, particularly those that interface or are adjacent to the to balconies, are showing signs of deterioration at isolated sections which are likely due to water ingress from the balcony parapets.
2.6 At-Grade Waterproofing Assemblies
The condition of the concrete slab over the underground parking is structurally stable, however the waterproofing is in a poor state. Localized repairs at the perimeter of the building and injection of the concrete slab from below may be required as issues related to water ingress. This may be required on a continuous basis around the perimeter until the full waterproofing membrane is replaced, but may not be completed for at least another five years.
Based on the observations and descriptions above, certain areas of the building require extensive renovations where others appear to be in stable condition and only require isolated repairs and maintenance. As for the areas that require immediate attention, the following recommendations shall be top priority:
- Systematically renovate the stucco walls at the east elevation including replacement of the windows at this elevation of the building with the option to retain and reinstate them.
- Apply a new paint finish to all stucco and exterior wood elements to blend renovated areas to existing areas.
- Complete a comprehensive refurbishment and maintenance program to the existing windows and doors.
- Systematically renovate all balconies and decks with new waterproofing membranes, new rainscreen cladding at parapets, new parapet flashing detailing, and other related improvements with the option to renew the sliding doors at the balconies and decks to coincide with the renovation of the balconies.
- Monitor the grade level waterproofing assemblies for any signs of leakage and attend to required repairs in an effective and immediate manner to minimize the occurrence of damage to the building or concrete slab.
Beyond the aforementioned, the other important recommendation arising from the building assessment is the strata corporation shall implement a regular ongoing maintenance and monitoring program of the proposed systems not renovated. The systems may include cladding, windows and doors to ensure their continued function and performance and magnify their longevity. At the same time planning for eventual renewal of the building components shall be encouraged.
For a variety of reasons, budget costs have been prepared for the recommendations of this report. Firstly, the strata corporation needs to make various critical decisions as to what remedial approach and strategies they feel would best serve their needs. The decisions depend on how long the strata owners have lived at Sunwater Dwellings or how much longer they plan to stay before moving on. The short-term and long-term needs will also determine the extent of the renovations as well as the overall impact of the project costs.
Secondly, for targeted renovations proposed, the information is still only conceptual and shall be confirmed by a more focused analysis of how the scope of work performance shall proceed. Even then, with envelop repairs, much of the actual work cannot fully be confirmed until removal of existing material to reveal the building infrastructure. Once further examination of the physical aspects of the building is conducted, drawings and specifications can be developed and accurate price bidding procedures can be obtained from qualified building restoration contractors. The costs can be compared to a reasonable degree of accuracy by labour and material factors.
Sunwater Dwellings is comprised of a three level wood-framed low-rise residential apartment building and a four level (two separate buildings) residential apartment building connected by a ground level hallway and common building and is constructed over a below ground parking garage. The building is currently occupied. Therefore proper coordination of the scope of work with the residents and resident manager is essential to minimize the impact on the occupants.
4.1 Existing Building Information
The building portion above grade is wood frame combustible construction. The parking garage that is below grade is a concrete structure with cast-in-place concrete and is non-combustible. This concrete aggregate is a suspended slab supported by concrete columns and perimeter foundation walls. The existing building envelope systems are comprised of the following:
- Cladding – stucco cladding fastened to oriented strand board sheathing at the main wall areas and wood panel cladding at the bay windows
- Glazing Systems – dual glazed, aluminum frame windows and sliding doors
- Balconies – plywood sheathing with liquid applied PVC sheet membrane
- 4th Floor Decks – built-up asphaltic roof membrane system on top of deck sheathing. Wood deck board walking surface above membrane.
- Eyebrow roofs – SBS modified sheet membrane system on top of deck sheathing
- Slab Assembly – Fluid applied polyurethane membrane on top of concrete suspended slab where parking garage extends beyond the building footprint. Landscaping materials and patio topping above membrane.
Other miscellaneous material such as strapping, soffit, and fasteners also make up the building envelope depending on the various wall systems, but will be omitted for clarity. The main roof area is to be left alone and not be part of the scope of work other than being tied in at the perimeter with the exterior walls.
5.0 Project Intent
The current select components of the existing building envelope assemblies are allowing unintended water seepage that is resulting in damage to the existing wood structure at some locations. As a result of these factors, a targeted renovation of the building exterior is required. The project intent is to address the various areas of unintended water egress or envelope failure and renovate the building exterior in a targeted nature as outlined in the specifications and illustrated in the details provided. The general project scope is to do the following (see also Section 3.0 under Recommendations):
- Complete a comprehensive replacement of the balcony, deck, and eyebrow roof systems throughout the complex.
- Replace the existing stucco cladding system throughout the east elevation of the east building and various other wall areas with a new rain screen stucco cladding system.
- Replace existing windows with new energy efficient polyvinyl chloride (PVC) frame windows at all rain screen stucco areas, notably the east elevation of the east building and various other specified locations.
- Replace existing waterproofing membrane at the suspended concrete slab planters on the east side of the east building.
6.0 Homeowner Protection Act
This project is to include the mandated renovation warranty insurance requirements of the Homeowner Protection Act for the specified repair work at the east elevation of the east building. The reason for this is because the building is still less than 25 years in age and the work at the east wall covers more than 60 percent of this elevation. The remaining portions of the renovation scope are exempt from the above note insurance requirements. An insurance provider selected would follow up to make sure all bidding contractors are registered with it. In addition to specific warranty coverage called foe in the specifications, the following General Contractor warranty coverage is to be provided:
- 2 year labour and materials coverage on all existing elements installed or reinstated as part of the project.
- 5 year water penetration coverage on all water penetration into the building structure from the new systems installed as part of the project.
- Contractor bonding: 50 percent labour and material payment bond, and 50 percent performance bond that is to be maintained for a period of two years beyond the date of substantial performance.
- All necessary insurance coverage in compliance with the latest requirements in the insurance requirements document.
7.0 Contract Method
Certain items noted as part of the scope of work portion of the work that are considered quantifiable and are to form a lump sum fixed price for the project. Other items that are anticipated to be required, but cannot be accurately quantified are to form part of the contingency allowance or cash allowance and will be completed on an as required basis to be directed and administered by the consultant. Work to be excluded from the project are removing personal items from the interior or exterior and not attached to the building, and removal of any plants and landscaping to specifically be salvaged for reinstatement by the strata owners.
8.0 Proposed Scope of Work
This section describes the scope of work to be completed with new proposed products. There may be some items of work not specifically noted but that may still be required to meet the true intent of the project specifications. The contractor shall ensure and note any conflicts that may arise within the documents for resolution and clarification by the consultant before proceeding. In most cases where the existing materials are to be removed as instructed shall expose existing structure. If the event that the existing structure is damaged and requires replacement, a professional engineer shall be retained to provide detailed structural drawings to replace damaged structural components.
The following pertains to the base scope portion of the project and is broken down to components. Some require additional steps for clarity, while other that only require brief finishes and repairs are only generally modified:
8.1 Exterior Wall Types 1 and 2
- Existing stucco walls are to be removed including all accessories, flashings, building paper and other related components to expose the existing wood sheathing.
- Install new rain screen stucco cladding assemblies identified over existing framing and sheathing including all required flashing, accessories, sealants at the intersections, and related detailing and other components specified.
- Apply a new paint finish throughout.
- Install all new electrical outlets including boxes, plugs and covers, vent flashings, and hose bibs at all new cladding areas.
- Exterior Wall Type 3
- New stucco cladding assembly at balcony and deck parapet walls.
- Remove the existing wall structure and install new framing sheathing.
- Install new rain screen stucco cladding assembly over new framing and sheathing including all required flashings, accessories, sealants at intersections, and related detailing and other components.
- Apply new paint finish.
8.3 Cedar Board Assembly at Balcony and Deck Posts
- Replace existing wood posts and retain posts in good condition unless specified otherwise by consultant.
- Install new cedar board cladding over new or existing post structure including all required flashings, accessories, sealants at intersections, and related details.
- Apply new paint finish.
8.4 Existing Stucco Cladding Assembly
Not much is required for this wall system being undisturbed, other than an extra coat of paint finish for protection.
8.5 Existing Wood Panel at Bay Windows
A new paint finish shall be applied along with new sealants at wood joints between the existing cladding and the exterior windows. New flashings are needed to cover and protect the sealants between joints. At all wall surfaces with large spans greater than one floor, a through wall flashing between cladding needs to be installed horizontally to provide water breaks out toward the exterior.
8.6 Windows and Doors
Existing aluminum frames, double-glazed windows and sliding doors need to be removed to allow for installation of waterproof membranes, new framing, and new windows and doors. The windows and doors may be reinstated on the 3rd and 4th floors.
All balconies to be repaired are to have existing waterproofing, sheathing, furring, and stucco removed to expose the framing. All existing material shall be replaced with new and tie in where balcony surface meets the wall surface. Adequate tie in shall involve enough membrane overlap to prevent water ingress.
The decks apply to water tightness over living spaces. Proper and continuous ventilation between the interior and exterior needs to be provided to prevent air from being trapped, and therefore also to prevent condensation. The vapor barrier installed shall be applied to the warm side of the deck.