wrote in message
ups.com...
I have a cathedral ceiling with no insulation. Construction is 2x6
pine tongue and groove sitting on 4x10 beams. These beams are spaced 4
feet on center. The roofing material is Cedar Shake. What I would like
to do is install 4" styrofoam sm (R20) between the beams and finish
with pine again to retain the original look. Will I encounter
condensation problems? If so what needs to be done to rectify the
problem? Thanks.


Are you absolutely sure there is NO insulation? Anything built in 1960s
on up, the common practice was to lay down some sort of fiber panels over
the T&G, then paper and shingle over that. Are there slats or something
under the shakes to keep the back of them dry? How old are the shakes?

I'd get a good roofing contractor in, and price what it would take to
insulate from the outside- pull off the shakes and any low-R fiber panels,
reskin the roof with modern high-R foam panels designed for exterior use,
and lay a new roof surface over that, with suitable flashing and trim around
the edges to make it look right. (My preference would be some sort of
standing seam metal- I hate the upkeep of shakes. If you want the shake
look, they make plastic ones now that outlast wood, and don't rot.)Note that
this would take a roofing company experienced in commercial-grade work, not
the typical residential re-roofer that uses low-buck crews hired from
anywhere.

Unless you give up a foot of headroom, and install a whole 'nother ceiling
system and faux beams below, I don't think there is any good way to do what
you are proposing, and have it come out looking right. Lots and lots of
cracks between warm and cold material, and if condensation happens, lots of
crevices for stuff to grow.

aem sends....