On Mon, 17 Oct 2005 03:16:04 GMT, "ESM" wrote:

Downside to blown in stuff is it settles over time. My house is 25 years
old, had blown in fiberglass and it settles down to around an R10 value.
Probably was R19 originally. So now I'm at R30 range.

Attended a house building course years ago when I was building mine
with sweat equity. On insulation calculations the data was that up
to R30 the gain in insulation efficiency is a straight slope upwards.
After R30 the slope flattens which is to say any gain in insulation
efficiency ( reduction in heat loss) after R30 is very marginal. That
is you won't get your money's worth beyond R30.