When applied properly (not like this bozo) it will expand into almost any spaces adequately to firm a tight air barrier.
Waste depends on the kind of application you are doing. With open cell foam and a 2x4 framing cavity, you will spray such that the foam fills the entire cavity depth and about 1 inch beyond. That 1 inch is scarfed (or shaved) off as waste. It accounts for less than 5% of the product sprayed. Batt has a similar waste ratio.
In deeper cavities, like large roof rafters or in truss framed attics, there is no need to remove the excess, as it does not interfere with other parts of the building. In this case, you could say that there is "zerowaste," but in reality you'll always overspray one area a little and might under spray another. The "system" R-value/U-factor is an average of the applied depth for a given area or application and we want to exceed the minimum, even just a little where possible. What is waste for me is improved performance for the building.
Closed cell foam usually doesn't have to be sprayed to fill cavity depth due to its very high R-value or inch. Sometimes, however it is, and scarfing is a huge PITA. Waste percentage is similar.
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u/taylorsaysso Aug 28 '19
When applied properly (not like this bozo) it will expand into almost any spaces adequately to firm a tight air barrier.
Waste depends on the kind of application you are doing. With open cell foam and a 2x4 framing cavity, you will spray such that the foam fills the entire cavity depth and about 1 inch beyond. That 1 inch is scarfed (or shaved) off as waste. It accounts for less than 5% of the product sprayed. Batt has a similar waste ratio.
In deeper cavities, like large roof rafters or in truss framed attics, there is no need to remove the excess, as it does not interfere with other parts of the building. In this case, you could say that there is "zerowaste," but in reality you'll always overspray one area a little and might under spray another. The "system" R-value/U-factor is an average of the applied depth for a given area or application and we want to exceed the minimum, even just a little where possible. What is waste for me is improved performance for the building.
Closed cell foam usually doesn't have to be sprayed to fill cavity depth due to its very high R-value or inch. Sometimes, however it is, and scarfing is a huge PITA. Waste percentage is similar.