"FrozenNorth" wrote in message
...
Been lurking here quite a while...

The situation is this, I have a south facing sunroom/extension on the back
of my house built by the previous owner, I've hired a contractor to
replace
the windows, exterior door and exterior siding ...
I plan on doing the interior myself, new wood casing/ledges around the
windows, beadboard on interior walls/ceiling, probably in pine. It gets
*very* hot in there in the summer, even on sunny days in the winter. So I
was figuring on using an exterior grade finish on the pine, for the extra
UV protection. [...]

I have no opinion on the finishes problem but this is important:
Get the correct coatings on all the glass to filter out the UV rays.
Otherwise the sun will be very destructive to anything and everything which
is in there; fabrics, books, plastics wood, whatever. The filters will also
keep the temperature down considerably. Then you won't have to worry about
exterior grade finishes indoors.

Tim w