1/2 lb Spray Foam, Light Density, Open Cell (Icynene)
In most residential and commercial cavity wall/ceiling applications we can offer the same high performance envelope solution at up to 50% less cost than 2 Lb foam systems. We can explain the differences and give you options that will give you the best combination of value and performance to meet your budget.
Here are some of the details that you need to know about the main physical properties of light density foams ½ lb spray foams.
-1/2 lb spray foam is not a vapour barrier; it is considered a breathable foam system which is able to provide drying potential to a wall, ceiling or floor assembly. Drying potential is being recognized more and more by the building science community as an important performance characteristic of building envelopes. Where a vapour barrier is required it can be provided by vapour barrier coatings or paints, conventional polyethylene, or in many instances by other components of the assembly. For example in a floor assembly the plywood subfloor is recognized as a vapour retarder since it is on the warm side of the assembly.
-Icynene ½ lb foam and 2 lb spray foam systems are air barriers and meet the performance requirements as set out by the National Research Council. To be considered an air barrier a spray foam must have an air permeance of less than 0.02 L/s.m2 @ 75 Pa as per ASTM test 2178. Many contractors assert that open celled foam insulations are not air barriers but this is not true. Not all ½ lb spray foams meet this requirement. Icynene does. Ask for a data sheet to substantiate this claim.
-Icynene will not wick water, does not soak it up like a sponge. This is one reason we choose Icynene as our preferred product. Water can be forced into it under pressure (ie: held under water) but when removed it will dry rapidly and not lose any of its performance characteristics.
-Icynene is water blown foam. The cellular structure of the foam is created when the water in the foam resin (A component) reacts with the isocyanate (B component). The water boils off, expands and creates the cellular structure trapping air in the cells. Water blown foams such as Icynene are by far the most environmentally friendly spray foam solution. 2 lb foams use a chemical blowing agent known as HFC 245fa. It is does not have an adverse effect on the ozone as previous blowing agents did but it is a greenhouse gas with a Global Warming Potential (GWP) of approximately 950 as designated by the Environmental Protection Agency in the US. Icynene and other water blown foams give off carbon dioxide as a byproduct of the chemical reaction. Carbon dioxide has a GWP of 1.
For even more info please download our Spray Foam eBook