<html> Tom, what I tell people is this: if they can lay their hands on the wall at different times of day, and it feels the same, they don't really have much to worry about, assuming, of course, that it isn't near a leaky window. It's also much better, of course, if the sun doesn't beat on outside of the wall. If they are worried, they could drape a piece of quilted fabric down the back of the piano. With a piece of plastic film, I might worry about condensation. If I cover over the back of a piano, I sometimes put wads of steel wool at the bottom between the back posts, so that mice don't find a happy sheltered home back there. I find that direct sun through a window is much more dangerous than an outside wall in a fairly new house. Susan Kline At 11:56 PM 12/1/2002 -0700, you wrote: <blockquote type=cite class=cite cite>Dear list,     can you give  some suggestions for a customer`s following inquiry:             - in a 20 year old home she needs to put her piano on an outside wall (she doesn`t know if the home has inside and outside moisture barrier but says it has insulation).           - her question is:  - is there some type of buffer that can located between the piano and the outside wall to compensate for the piano having to be placed there?  e.g.- plywood                                                                                                   - cloth                                                                                                   - plastic thanks in advance, Tom Carpenter Berthoud, CO    </blockquote></html>