Construction Photo 70 Tradd

The addition under construction

Spray Foam

Notes Based on  “Spray Foam Details & Myths Explored!  Chemistry, Application and Field Performance”, presented by Bob Duke, elected member of the Board of Directors for the Spray Polyurethane Foam Alliance.

Vistit SPFA website for in depth information www.sprayfoam.org

Spray Foam Insulation

What is it?
•    Spray Foam is a Polyurethane Insulation
•    It is a mixture of  – 1) Dimethyl Isocyanite and 2) Polyol Resin Blend
•    Alone Dimethyl Isocyanite is very toxic, when mixed with the Polyol Resin Blend it becomes inert
•    The product is not green – certain aspects of the Resin Blend can be green based, but there is always Dimethyl Isocyanite in the mix. It can be at most 7-8% organic content.

What types are there?
•    Low Density, AKA half pound, is open cell foam
•    Medium Density, 2 lb, is closed cell residential foam
•    High Density, 3lb, is roof foam
•    Open Cell has the possibility of absorbing water, according to the Mr. Duke.

•    Open Cell is a little better with sound absorption
•    Open Cell should not be used in a crawl space or unconditioned space because it can absorb humidity.

What happens when the mixture combines to create the foam?
•    It is an exothermic reaction that happens, creating heat when the two are combined
•    a blowing agent is needed in order to cool the foam as it is combined.
•    245fa is the blowing agent used now replacing the old CFC’s that ceased to be used in 2005
•    The SPFA states that there is no VOC offgassing by foam.

What are the R values?
•    Spray foam R values are dependent on the application
•    Hot foam should never be sprayed on top of hot foam – it makes the foam expand more and get a higher puff, but the insulating value is not the the same.
•    Get a good applicator, and it’s worth testing the foam by taking samples after the application -
•    There should be a felty feel to the interior of closed cell foam, and you can test it by weighing it.
•    closed cell, when applied correctly, achieves an R Value of approximately 7 per inch
•    open cell, when applied correctly, achieves an R value of approximately 3.5 per inch

Application
•    Temperature, Humidity, and Temperature of Substrate influence how the application goes on.
•    Cold absorbs more, hot weather gives a better yield in application
•    Cures 90 % in one hour, fully cured in 24 hours.
•    Should be applied in layers – 1 inch per pass.
•    Closed cell foam should look like a pebbly wall when complete

Other Information
•    Unless your foam exceeds the ASTM testing and your code official approves it, you probably need an ignition barrier applied to the foam if it’s in an attic storage space.
•    This is a product that is extremely difficult to remove, requiring scrapers and chisels.
•    Conversely the product significantly strengthens the rigidity of walls and increases the resistance of roofs against uplift.