I am an Architect in Toronto. I am designing a new roof addition to a row house building. Because of existing conditions and the shape of the new roof. It may be easiest to use closed cell spray foam within the areas of the joists. My question is when spray foam is used in this situation do I need to worry about how the joist members may be thermal bridges? It is not common to provide a little bit of rigid insulation to protect the joist members? The additional layer of outboard insulation will require an extra layer of plywood above the insulation which will add to cost.
The Canadian National Building Code references the CAN/ULC S705.2 National Application Standard which must be followed during all installations of 2lb medium density closed cell polyurethane foam. Every installer of CAN/ULC-S705.1 compliant medium density, spray applied foam must be licensed in order to spray foam and hold valid photo ID issued by their Quality Assurance Program (QAP) provider showing their license is in good standing.
Heat which is created elsewhere that is transported by means of a fluid, such as water or in our case air. Spray foam insulation's most important attribute is the ability to air seal creating a custom airtight envelope within the building structure. The added benefit to air sealing is the ability to block convective heat transfer from interior to exterior during heating months and vice versa during cooling months, as the heat cannot escape through gaps in the buildings envelope without the aid of air movement from infiltration as a means of transport.
Sta-Kool 780 Siliconized Acrylic White Elastomeric Roof Coating Sta-Kool 780 Siliconized Acrylic White Elastomeric Roof Coating is a high quality flexible white acrylic roof coating. Product is enhanced with silicone for improved water resistance adhesion and life expectancy. Product resists cracking peeling while offering tremendous durability and long term life. The coating forms a durable protective barrier which ...  More + Product Details Close
Note:  A board foot is defined as a 12" x 12" square at 1" thick. Actual output can be affected by a number of factors including temperature and humidity. The theoretical yield has become an industry standard for identifying certain sizes of two component kits. Theoretical yield calculations are performed in perfect laboratory conditions, without taking into account the loss of blowing agent or the variations in application methods and types.

Henry 587 Dura-Brite White Elastomeric Roof Coating is Henry 587 Dura-Brite White Elastomeric Roof Coating is a premium high solids formula offering better weather protection solar reflectivity and longevity than economy grade reflective roof coatings. Cured coating forms a permeable membrane which prevents liquid infiltration but allows moisture vapor to vent or breathe out of underlying substrate. Recommended ...  More + Product Details Close

Spray Foam Contractors


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The roof must be thoroughly cleaned, and allowed to dry thoroughly. This is a critical step to ensure a successful coating application. Be careful not to damage the lap seams. Care should be taken when pressure washing not to disturb the integrity of the underlying roof membrane particularly where there are adhered seams. Refer to the specific coating manufacturer you are using for their specific requirements for roof preparation.

Roof Coating Seal

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