Insulation board under electric radiant floor heat installed on wood subfloor
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Hi All,
I am installing electric heating system by Warmup in my kitchen and bathrooms under tile and on top of plywood subfloors. I am considering installing the 1/4″ insulation board on top of the subfloor – but it is very expensive. Wondering how much heat is lost down into the subfloor and whether it is worth trying to save when saving it costs so much! Would appreciate thoughts.
Thanks much
Andy
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Replies
Andy,
It depends on what is underneath the floor. No matter what, adding in 1/4" of insulation will not do much.
If it is an unfinished basement/crawlspace, best to add insulation batts into the joist bays underneath.
If it is a finished basement, the heat is not lost as it stays inside the house. An un-insulated floor is around R3, my guess is you would loose about 1/4 of your heat to the basement.
If you want to insulated under the mats, I've used cork+tile backer under tiles before. 3/4" cork (R2.5) would help a bit.