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Spray Foam Insulation & Building Science

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The Principles of Building Science

Practicing building science, also known as a “systems approach,” means accounting for the ways all building components interact, including the foundation, walls, roofs, doors, windows, insulation and mechanical systems. Doing so is critical to optimize building performance and prevent building failures. The principles of building science include:

  • Creating a continuous air barrier combined with proper mechanical ventilation
  • Providing thermal resistance
  • Managing moisture
  • Improving indoor air quality
  • Using appropriate heating and AC systems

Icynene spray foam insulation addresses all of these principles to help building and design professionals practice building science techniques with ease. The benefits are verified through extensive research and testing performed on all Icynene products.

How Icynene Spray Foam Insulation Plays a Vital Role

Building scientists are now stressing the importance of air barriers like Icynene spray foam insulation in building design and construction. This is partly because many buildings constructed in the past decade without air barriers have already experienced major failures in terms of moisture damage and mould caused by condensation, which stemmed from air leakage.

In addition, research shows that without an air barrier, insulation cannot deliver optimal energy efficiency or comfort. This is why air barriers are now a critical part of code and industry standards such as ASHRAE 90.1.

Limits of R Value

R value measures insulation’s ability to limit conductive heat flow (heat that is transferred through it). But the primary method of heat transfer is not conductive heat flow — it’s air leakage (convection), which can account for up to 40% of a building’s energy loss.

In addition, R value only does so much to prevent even conductive heat flow. Beyond a certain point, increasing insulation R value makes very little difference, if any. In fact, the cost of increasing R value alone can actually far outweigh the energy savings that result, meaning it will take much longer to break even.

Therefore, the best way to increase efficiency is not merely to increase R value, but rather to combine R value with an air barrier. Icynene spray foam insulation provides both in a single step.

Spray Foam Insulation as a Vapour Barrier

Approximately 99% of the water vapour that travels through a building envelope enters through air leakage. Icynene spray foam insulation controls air leakage so effectively that a separate vapour barrier is often not necessary. In fact, when a building code requires it, closed-cell ICYNENE MD-C-200™ spray foam insulation officially qualifies as a vapour barrier in Canada.

When open-cell spray foam insulation is used, a separate vapour barrier may or may not be necessary. Exceptions include places with high interior relative humidity, such as interior swimming pools.

When a separate vapour barrier is needed, it should be applied to the warm side of the wall. vapour barrier paint is often the simplest solution. This kind of paint can be applied to the surface of drywall or sprayed directly onto cured Icynene spray foam insulation.

The following paints have been applied directly over ICYNENE LD-C-50® spray foam insulation and tested. They achieved a permeance rating of less than 1 (< 60 ng/Pa.s.m2) and qualify as vapour barriers according to building codes in Canada.

  • Benjamin Moore® Fresh Start Primer – Product Code K024-00
  • CORO-BOND™ Universal Primer – Product Code 1147-111


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