Hi - our roof has one layer of cedar shakes & 2 layers of asphalt shingles (no plywood). Most estimates for replacement are for tearing off the cedar, putting up plywood & new asphalt shingles. We have one individual who says he can put water & ice paper right over the cedar shakes & then a layer of asphalt shingles. I realize this is not the best route, but we are getting ready to sell the house, which is only valued at about 65000 (built in 1930), so it is very tempting. The estimate is MUCH cheaper. Does anyone have any experience with this? Thanks!

The best advice I can give you is: DON'T DO IT
The best thing to do is go with the plywood deck and apply new shingles. When you sell a home it's required by law for the existing homeowner to disclose any faults or defects via a seller's disclosure form. You may not only lower your selling price, but be held liable for any damages that are incurred due to faulty roofing. Look at it this way, it's an investment in your investment. Besides, what if the potential buyers get a home inspection, and you haven't told them about the roof? How does that make you look?