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Presented By Dr. Mark D. Hagel, PhD., P.Eng Executive Director at the Alberta Masonry Council PhD. in civil engineering, BSc. in civil engineering and a BSc. in actuarial science and applied mathematics, all from the University of Calgary. Technical Services Engineer for CCMPA Building envelope and Structural Engineer at Halcrow Yolles (certified EIFS inspector) Depending on the building environment, wood has been shown to be an appropriate building material for single family residences, where sloped roofs and a limited number of stories keep the environmental and structural loads relatively small. Segregated dwellings and limited height reduce the fire risk and decrease noise transmission to adjacent dwellings. Wood’s suitability for multi-family mid-rise residences, which have a significant increase in their structural and environmental loads fire safety risk and noise generation (occupant comfort) requires much more detailed design, construction and inspection. Wood treatments such as Pinkwood are addressing this but these treatments are relatively recent developments. Current design and construction practice of low to mid-rise multi-family residences have led to several building envelope failures in Alberta. We will investigate the building science behind these failures and methods to mitigate penetrations of the building envelope. The Report Confirms many of the issues with Building Envelope in low to mid-rise multi-family residential buildings. Some Shoddy construction with inadequate stucco depth. Recommendations that trade certification for uncertified trades such as wood-framers, stucco installers, etc. The report does not identify some of the other failure mechanisms or address the fact that stucco clad wood-framed condominiums not built during the boom are also failing. Mr. Michael Ball, associate and senior project manager for the buildings and facilities division of Morrison Hershfield Ltd., has been involved in building restoration projects within Calgary for the past 10 years. Mr. Ball was recently quoted in the Calgary Herald article “Calgary condo owners await solutions to long, soggy saga - Alberta seeks new standards, consumer protection” on May 15, 2011. “I could point you to at least 200 condo suites around the city that are under restoration right now that are less than 10 years old” – Michael Ball, 2011 “We're in the infancy of really understanding the scope of the problem. Whether it's catastrophic or not is a matter of whether you're living in a condo that's under restoration.” – Michael Ball, 2011 "I think the scope of the issue is far worse than what industry and government are saying"– Michael Ball, 2011 Mr. Ball further commented that due to the amount of rain Calgary gets per year, it can take up to five years for condo owners to notice water penetration in their building envelope - a fact which leaves exact numbers of affected buildings hard to determine. Bella Vista, Calgary Built 2002 Complete building envelope replacement starting in 2010 $5 million cost to owners Stucco cladding on wood sheathing PVC and asphalt shingle roof Edgecliffe Estates, Calgary Built 1990 Stucco Replacement $10 million cost to owners Stucco cladding on wood sheathing Asphalt shingle sloped roofing Psychrometric Chart Determining the location of the Dew point From the psychometric chart it can be seen that the condensation forms in Alberta when temperature is approximately 4qC or below. Next slide confirms the average temperature in Alberta is frequently below 4qC this frequently (at least 6 months per year) Average Temperatures in Alberta Multi ltti-family residential ial all buildings bu uiildings with wood od framed ffr d construction – A typical example e Flat roofs over a large foot print Face sealed Stucco on wood sheathing and framing The insulation is usually installed on the interior between the wood studs to increase useable interior space The vapour barrier must be on the warm side of the insulation and therefore is placed between the stud and interior drywall finish Typical Wall Cros Cross sss s-Section s of stucco clad wood framed residential wall all Using 2D finite element Thermal modeling software like THERM 6.2 the location of the dew point within the wall can be established. Thermal model of a wood framed stucco clad wall (THERM 6.3.2) • • • • • • ¾” Stucco 2.5 lb./yd2 self furring metal lath ½“ Plywood sheathing 5- ½“ Batt. Insulation ½” Interior gypsum On concrete foundation Thermal model of a wood framed stucco clad wall (THERM 6.3.2) The dew point falls within the stud cavity. Insulation between the studs means condensation can occur and be trapped by the insulation. It demonstrates that on wood stud stucco clad structures, condensation will form in the stud cavity if warm moist air can breach the vapour barrier. Typically 6mil polyethylene sheet is used for the vapour barrier With a vapour barrier that is interior to the structure, it is difficult to seal around the beams, floor joists and services) Also 6mil polyethylene sheet is not self-healing and numerous penetrations by fasteners and services it is almost guaranteed vapour is in the stud wall Mould and rot result from moisture being trapped by insulation against the wood framing and sheathing This has been demonstrated by numerous documented failures in Calgary and Edmonton low-rise condominiums many of which are less than 10 years old. Unfortunately it is not cost effective to design buildings to be as water tight as submarines. Water will get in to the system so we must provide a method for water to get out. EIFS was not initially designed to clad wood sheathing, it was designed in post WWII Europe to cover damaged masonry or concrete. Masonry and concrete can store moisture without mold or rot. Stucco and EIFS that do not have an unobstructed drainage plane with through wall flashing to direct water out of the cavity, and a vented cavity to dry out the components trap water against the Air barrier/Water Resistant Barrier (WRB). The WRB is often asphalt impregnated building paper (30 minute building paper) and typically two layers. This membrane is compromised after being saturated for 30 minutes. Stucco is cementitious and readily absorbs and stores water. This water can be trapped against the lath and WRB. Large flat roofs are often flashed with a small parapet cap flashing that does not adequately shed water away from the walls increasing the importance of a well sealed building envelope. Light-weight wood framing is not designed structurally to support an adequate roofing system for large foot-print flat roofs. Single-ply roof membranes on wood sheathing are used instead of fluid applied Built-up roof or hot rubberized asphalt. Flat roofs with parapets that have small parapet flashings and no overhangs for clean lines do not direct water away from the walls. An unsealed envelope at the roof wall junctions can occur. Plank sheathed roof decks are not monolithic and can allow direct ingress of water if a single-ply unprotected membrane is penetrated. Un-protected single-ply roof membranes (TPO, EPDM, PVC) on wood sheathing are often used instead of built-up roof or hot rubberized asphalt to avoid torch on to a flammable substrate. Poorly installed windows and doors (inadequate adhesion between non-compatible roof membranes) Inadequate balcony membranes (single ply). Non hydrophobic batt. insulation in the studs stores moisture Timber roof and wall sheathing that does not have the ability to store moisture and rots or molds Unvented wall cavities without adequate drainage in combination with flat roofs with no overhangs that do not shed moisture away from the walls. In short, residential grade design and construction for commercial sized buildings subjected to commercial sized environmental loads requires a high level of attention to detail by designers, installers and inspectors if it is to perform for the intended 25 – 50 years. The construction method was first developed in the early 1960s by the National Research Council of Canada. In its purest form, the method is known as PERSIST — an acronym for PressureEqualized Rain-Screen Insulated Structure Technique. A superior form of building envelope design and construction for cold climates by installing both the air/vapour barrier and insulation exterior to the structural framing according to the PERSIST method. The exterior air/vapour envelope is: 1. 2. 3. more easily installed as a continuous system Insulation on the exterior provides for less thermal bridging, alleviates water vapour being trapped in the insulation by Pressure equalized (vented) cavity allows moisture to dry. Typical Wall Cross sss-Section in Commercial/Institutional Walls ls • • • • • • 4” Brick 1” Air gap 3” XPS Insulation 8” Concrete Block ½” Interior gypsum On concrete foundation The dew point falls on the exterior of the building within the vented air space and insulation. Insulation condensation can drain and dry with venting. If condensation does occur it absorbed by the masonry without mould or rot. Designers builders and inspectors are confronted almost daily with new products It is important especially with performance based code requirements that building components meet all the performance requirements and that the testing on the component meet requirements that are relevant to the Alberta built environment. MILRISE CONDO FIRE – CALGARY 2009 CONDO FIRE – EDMONTON 2010 CITADEL HOME FIRES – CALGARY 2009 CITADEL HOME FIRES – CALGARY 2011 Low to mid-rise wood-framed multi-family residential buildings are typically not designed to support the additional structural load of concrete block partition walls, firewalls, and infill walls. Typically Fire-rated gypsum board is used. Although the gypsum can resist the fire for two hours (CAN/ULC-S102 Surface Burning Characteristics of Building Materials and Assemblies, ASTM E119-11a and ASTM E8411b to achieve the 2 hour rating watch what happens when it’s subjected to fire hose water pressure. Cautions with Performance vs. Prescriptive requirement As was seen in the video clip the fire hose penetrates through the wall in 37 seconds or 10 seconds for the fibre reinforced drywall. Compartmentalization of the fire is not achieved by gypsum and wood-studs. The destruction of the wall can add air to the fire and increase the intensity if the fire has not been doused. The strength required for these sized building requires engineered wood which use flammable glues to achieve the strength. Wood-framed structures are typically not designed to support concrete floor slabs. The floors are typically engineered wood floors that burn hotter and quicker and jeopardized the lives of both occupants and firefighters. Occasionally, the floors may have a thin concrete (like Gyp-creteTM) topping for fire and noise reduction but that topping (typically ¾” to 1-½”) will not resist fire like the typical 4” – 6” floor slab. If the building is clad in vinyl siding the fire risk is considerably amplified as this is a combustible structure wrapped in a highly combustible cladding. Fire treatments (Pinkwood) have also been developed to address these concerns but are still in their infancy. If the wood is fire treated….it is fire resistant not fire-proof. Currently there is a standata in Alberta that two hour firewalls be constructed of concrete or masonry. I would encourage Alberta Building and Fire Code decision makers to maintain this standata especially with the impending adoption of 6 storey wood-frame buildings. Concrete and Masonry are Fire proof not fire resistant and don’t have to worry if the treatment is going to perform in 10 years as it does today Design an exterior envelope – with a protected fluid applied or SBS mod bit roof membrane and self-healing air/vapour barrier on exterior of wall sheathing. Use a water resistant sheathing such as exterior glassmat gypsum (DensGlass Gold, Glassroc, etc.) or Treated OSB ( Pinkwood, etc.) Use Pinkwood treated TJI joists for Fire and mould resistance Use non-combustible cladding where possible (brick, split face block, natural/manufactured stone, Hardie) Avoid Vinyl and wood siding. Specify concrete block partition, infill and fire walls (a 125mm (5”) unit fully grouted is 2hour fire rated with STC=50) Let the structural engineers figure out how to make block walls work with a wood-framed structure. Use exterior self-healing air/vapour barrier (Blueskin, Grace, Soprema) and exterior insulation. Use stucco over masonry for better moisture management OR Design drained cavity rain screen walls for all stucco and EIFS applications on wood sheathing. Properly tie in window and door membranes to wall membrane Properly flash around services, windows and doors On flat roofs avoid the use of unprotected single-ply roofing and be cautious with PVC as it is not compatible with the typical asphalt and silicone sealants many other building envelope products and will require special attention to products and substitutions. Use hydrophobic exterior EPS or XPS insulation where possible and avoid batt insulation in attic space Use sloped roofs where possible to increase watershed and reduce ponding. MASONRY MANAGES MOISTURE, NOISE, AND FIRE!! 2004 New Condo Buyers in Greater Vancouver Report by Cement Association of Canada. The cost of a concrete condo in Vancouver is only 10% - 15% than the same woodframed condo. 46% of people surveyed in the same report would be willing to pay 10% to 15% more for concrete condo. 74% of people are willing to pay 5% to 15% The leaky condo crisis that struck Vancouver 15 to 20 years ago is now materializing in Alberta as evidenced by the number of failures. Vancouver now requires all cladding to be drained and requires a 5 year building envelope warranty Alberta is introducing a warranty – it should be 10 years because our dry climate it can take longer for serious envelope issues to appear. Concrete or steel framed structure that can support a proper flat roof system, concrete slab floors, and concrete block infill and partition walls The masonry walls manage moisture and the concrete floors and block walls compartmentalize and insulate sound and fire. Self-healing air/vapour membrane (BlueskinTM Grace, Soprema) exterior to the building structure for easy tie-in (easier to wrap the outside of a box than the inside, selfhealing greatly reduces discontinuities from punctures by fasteners and services) Extruded polystyrene (XPS) or expanded polystyrene (EPS) insulation spray foamed at joints and penetrations. Exterior to the building structure. This reduces thermal bridging of the structure and services and is hydrophobic. Masonry veneer – rain screen wall with a drained and vented cavity. Can always stucco over the masonry if that aesthetic is desired. Concrete block firewalls, partition walls, and infill walls. Cast-in-place or pre-cast concrete slab floors. Theses elements compartmentalize fire and reduce noise transfer. Protected membrane fluid applied hot rubberized asphalt or 4-ply built-up roofing (for flat roofs). These are Self-healing membranes. Protected SBS mod bit is an affordable alternative. Extruded polystyrene insulation (StyrofoamTM exterior to the roof structure and sloped toward the drains (hydrophobic and great R-value) For sloped roofs use clay tile or rubber tile where possible. Masonry is recyclable. Masonry often uses recycled material in its manufacture (fly ash). Maintains Air Indoor Air Quality Is LEED applicable Indoor Air Quality: No off-gassing, toxicity or VOC's. Masonry does not support mould growth Website: https:/albertamasonrycouncil.ca.
