"cece e." wrote:

My last question before I get started with insulating my crawl space...
What does the "R" mean for insulation.

Resistance to heat flow. Specifically, Ohm's law for heatflow says I = E/R
Btu/h, where E is an F temp diff and R is the R-value of 1 square foot of
insulation. For A square feet, multiply the heatflow by A.

For instance, a 2'x8' R5 Styrofoam (vs R4 beadboard) wall that's 70 F on
one side and 30 F on the other will have I = (70F-30F)2'x8'/R5 = 128 Btu/h
of heat (38 watts) flowing through it.

Nick