Insulation Above Unheated Space

Old 02-01-22, 05:53 AM
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Insulation Above Unheated Space

I had an addition built a few years ago and had the underside of the floor spray foamed. In the winter the floor still get a wee bit cold. After doing a bit of research I realized that the spray foam did not fully cover every surface of the beams. Could the unprotected pieces be the reason for thermal transfer ? I have attached 2 photos .One showing my situation and the other showing how it should be done (I put the dotted line in). Would attaching R10 rigid ,3 sided ,strips help at all ?

Old 02-01-22, 06:03 AM
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What does a wee bit cold mean?
Also what is on the floor above this space?
A floor above an unheated space is always going to be cold in winter depending where you live,
Old 02-01-22, 06:06 AM
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You have an unheated space. Insulation only slows the loss of heat. It doesn't make heat so without heating the floor will be cold. The only way to have a warm floor is to add heat. Only then would I consider additional floor insulation and even then it will have very minimal affect.
Old 02-01-22, 06:24 AM
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Could the unprotected pieces be the reason for thermal transfer ?
But to answer your question, the uninsulated joist has less insulating value than the insulation between them, but the floor is sort of a average of everything..

2xX wood is about R=1.2 per inch, foam is R=6 per inch.
Old 02-01-22, 07:09 AM
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As Dane said, insulation does not add warmth - your floors are cold because cold air falls to the floor.

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