Understanding air barriers in mechanically attached low slope roofing assemblies for wind uplift

Wind flow over a mechanically attached roofing assembly (MAA) can lift the membrane and cause it to flutter or ?billow?. Air leakage into the assembly from building interior is a concern for wind uplift resistance of MAA. MAA is a growing segment of the low-slope roofing market however there is no widely accepted standard specification or test method to quantify air leakage through them. An experimental procedure has been under development for quantifying the air leakage rate of MAA. Assemblies with two barrier types, conventional polyethylene film and reinforced modified bituminous film, were evaluated. Data clearly indicates that MAA with barriers had lower air leakage rate than without. The air leakage impact on wind uplift resistance has also been evaluated under dynamic environment. Assemblies with barriers performed better than the assemblies without one.L?\ue9coulement du vent par-dessus une toiture \ue0 fixation m\ue9canique (TFM) peut soulever la membrane et provoquer un flottement ou un effet de vague. L?air qui fuie de l?int\ue9rieur du b\ue2timent jusque dans la toiture est probl\ue9matique en ce qui a trait \ue0 la r\ue9sistance au soul\ue8vement sous l?action du vent des TFM. Bien que les TFM repr\ue9sentent un segment en plein essor du march\ue9 des toitures \ue0 faible pente, il n?existe aucune norme ni m\ue9thode d?essai largement reconnues qui permettent de quantifier les fuites d?air \ue0 travers ce type de toiture. Une proc\ue9dure exp\ue9rimentale a fait l?objet de d\ue9veloppements, aux fins de la quantification du d\ue9bit des fuites d?air \ue0 travers les TFM. On a \ue9valu\ue9 des toitures comportant deux (2) types de membranes, soit la membrane de poly\ue9thyl\ue8ne classique et la chape de bitume arm\ue9 modifi\ue9e. Les donn\ue9es indiquent sans \ue9quivoque que les TFM avec membranes pr\ue9sentaient des d\ue9bits de fuite d?air inf\ue9rieurs que les TFM sans membrane. L?incidence des fuites d?air sur la r\ue9sistance au soul\ue8vement sous l?action du vent a \ue9galement \ue9t\ue9 \ue9valu\ue9e en environnement dynamique. Les toitures avec membrane ont mieux perform\ue9 que celles sans membrane.Peer reviewed: YesNRC publication: Ye

Building application and thermal performance of vacuum insulation panels (VIPs) in Canadian subarctic climate

Vacuum insulation panels (VIPs) have thermal resistance values, at the center of the panel, up to 10 times or more than those of conventional thermal insulation materials. In Canada, known for its predominantly extreme cold climate, the potential to apply VIPs in the building construction industry is estimated to be enormous, particularly with the introduction of the new 2011 National Energy Code of Canada for Buildings (NECB 2011). VIPs can play a major role in Canadian buildings to meet energy requirements of the NECB 2011. However, the lack of long-term performance credentials and various constructability issues are among the major barriers for mass application of VIPs in the Canadian construction industry. This paper presents the design strategy, construction details, instrumentation and thermal performance monitoring observations of a VIP retrofitted wall system in Yukon, located in Northern Canada. Experience gained from the construction process and available thermal performance data over a period of three years provide encouraging indicators for the constructability and long-term thermal performance of VIPs in Canadian subarctic weather.Peer reviewed: YesNRC publication: Ye