wrote in message
...
My house has T-111 type plywood panel siding on it. When it was
installed long before I bought the house, on an addition it was
installed much too close to the ground. Unsurprisingly, in these
areas, the siding has rotted and is falling apart.

snip

This doesn't answer your questions, but are you certain the old siding is
treated? I did this job several years ago and it shows no sign of rot or any
other problems:

http://flickr.com/photos/joearnold/158621674/sizes/o/

Also there are several 'patterns' and thicknesses of T1-11.
Joe