![]() ![]() In stick frame roof applications, ice damming occurs due to air leakage from the interior of the house. Ice damming occurs when the temperature of the roof surface is above the freezing temperature when the outside air is below freezing. This could be considered the ‘cold roof’ over ‘hot roof’ approach. This problem can be avoided by ‘over-cladding’ – adding another layer of sheathing on furring strips to the top of the panels. This can also happen with stick-frame or rafter type roofs (See APA publication K310N – “How to Minimize Buckling of Asphalt Composition Shingles).” One of the key concerns to avoid shingle buckling or ridging than can also lead to this issue is to ensure that the underlayment and roofing are applied over a dry roof deck.Īlthough the ‘telegraphing’ at panel joints in no way has any structural effect on the roof assembly, there is the small matter of aesthetics. The moisture content in the top OSB layer of a SIP roof assembly changes regularly with the seasons and can result in the panel joints ‘telegraphing’ through asphalt shingles (other roofing materials such as wood shingles, shakes and metal roofing are not affected). Having said that, the choice of shingle colour, roof orientation and geographic location will likely have a more profound effect on shingle life than the effect of a slightly higher shingle temperature. Generally speaking, shingles installed over unvented ‘hot roof’ assemblies like SIPs operate at a slightly higher temperature and therefore some reduction in shingle life may be expected. The greater the temperature and UV exposure, the shorter the life of the shingle. ![]() The durability of asphalt shingles correlates directly with temperature and ultra-violet radiation. There are some pretty strong arguments for the practice of ‘over-cladding’ a SIP roof. So, the subject of this blog is ventilation of roof cladding systems above the roof deck or top skin of the SIP. To summarize, the cross-ventilation requirement referenced in the code does not apply to a SIP roof. PIB_207_-_Building_Code_Roof_Ventilation_Requirements The Insulspan SIP system is a closed cavity building component that does not include ‘rafters’ as defined above, and since the EPS insulation is in direct contact with the underside of the OSB top skin of the SIP, there is no opportunity for a condensation plane to develop within the core of the panel. The International Residential Code (IRC) 2006 and the National Building Code of Canada 2005 each have a similar provision stating that ‘except where it can be shown to be unnecessary’, an enclosed attic which is defined ‘as the space formed by application of finish material to the underside of roof rafters’, must have cross ventilation. The type of ventilation discussed in this blog is not to be confused with roof ventilation referred to in most building codes. Review the Rain Screen Blog or the HVAC Requirements Blog. You may recall that in the previous blog we dealt with rain screen requirements for walls built with Insulspan SIPs and previous to that, in Part 1 of the series, we discussed HVAC requirements for buildings built with SIPs. ![]() The energy efficiency extends to the EPS foam itself, given that it takes 24 per cent less energy to produce EPS than fiberglass insulation of equivalent R-value.Welcome to Part 3 of my series regarding appropriate venting applications when building with Structural Insulated Panels (SIPs). In fact, the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN, conducted whole-wall R-value studies that showed a 4-inch SIP wall (nominal) rated at R-14 outperformed a 2×6 stick framed wall with R-19 fiberglass insulation, and was 15 times more airtight than its stick framed counterpart with fiberglass insulation. ![]() From an energy efficiency standpoint, the R-values are high and thermal bridging almost entirely eliminated. Building waste is also reduced substantially. Manufacturers claim that an average 2,000 square foot house can be assembled in one day.Īny cost comparisons to traditional framing techniques requires consideration of the time saved, and the fact that insulation and vapour barriers are integrated in SIPs. The fact that SIPs are delivered made-to-measure with all window and door blocking completed means they fit together quickly and precisely, needing only a boom truck. Prefabricated right down to window and door openings, SIPs assemble quickly with the help of a boom truckįrom an assembly standpoint, SIP’s require a much smaller crew than a stick-framed building. ![]()
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