by caseydog » Wed Oct 22, 2008 7:49 pm
I looked at this same thing, and found that the R-Value of Plywood sheets is not much worse than the R-Value of foam panels, in equal thickness. You could add a radiant barrier to your plywood and get a nice bump in R-Value, too. Put some Thinsulate material inside the walls, and you get a nice R-Value.
I'm going with 3/4 plywood on my next build. I'll probably use a radiant barrier and insulation in my roof, but just plywood on the walls. Here in North Texas, it is not unusual for summer temperatures to be around 40 C. And in January, we will often see freezing temperatures at night. I doubt you see that much variance in the UK.
Do some web searches for information on R-Values, and I think you will be surprised at how much information is available.
CD
My build journal is
HERE