Insulation Value of Wood
Wood's R-value is not trivial, but air leaks and bypasses often dominate the equation. April 11, 2008
I have a customer that is going to finish off the inside of a pole barn with 5 inch thick poplar and he would like to know its R value. I told him that I don't think it will be very much. He already has 2'' thick pink foam board and wants this to protect the foam and insulate. Can anybody help me give him an answer?
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
The link below has the R-value of 1.1 per inch of thickness for yellow poplar at 12% MC (Chapter 3, page 3-19). So, for 5" material, he would have 5.5 R value... not bad at all. Wood is a good insulator indeed.
The real problem with R-values in general is that air leaks and window/door leaks often result in more heat loss than the wall itself. In the case of a barn, the floor and roof can lose many times more heat than the walls. That is why we use perimeter insulation around the foundation and double the insulation in a roof.
(Special note: In a kiln with good air circulation, the extra roof insulation is not needed; it is only when interior hot air will rise to the ceiling that the extra insulation is beneficial in reducing heat loss.)
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