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
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 mold 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 UK and Irish Building regulations.
Limits of U Value
U value measures insulation's ability to limit conductive heat flow, the lower the U value the better (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, U value only does so much to prevent even conductive heat flow. Beyond a certain point, increasing insulation to reduce U value makes very little difference, if any. In fact, the cost of reducing U 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 reduce U value, but rather to combine U value with an air barrier. Icynene spray foam insulation provides both in a single step.
Spray Foam Insulation as a Vapour Retarder
Approximately 99% of the water vapour that travels through a building envelope enters through air leakage. Icynene spray foam insulation controls air leakage and the subsequent moisture laden air. It is important to remember that Icynene is not a vapour barrier and local product certifications and building regulations must be adhered to unless an assessment to BS 5250 or EN 15026 states otherwise.
When a separate vapour retarder is needed, it should be applied to the warm side of the wall. Vapour retarder 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.