Can you lay shingles on top of shingles?

The answer is yes, you can lay new roof shingles over old ones. But before we get started, one thing must be clear: adding new roofing over old (sometimes called a “re-roof”) is possible only with asphalt shingles (also called “composition shingles”).Click to see full answer. Also question is, is it OK to put a second layer of shingles on a roof?In most areas, building codes allow for up to two layers of shingles installed on a roof. If two layers already exist, you’ll need to remove the old layers before installing a new layer of shingles. Physically inspect the entire roof to determine the soundness of the wood roof decking, which is under the shingles.One may also ask, can you put plywood over old shingles? The existing asphalt shingles need replacement, so he plans to do a tear-off and re-shingle. Because the plywood roof sheathing under the shingles has become brittle and weak, he plans to install new plywood as well as new shingles. The new plywood will have to be nailed to the rafters or roof trusses. Just so, can you put 3 layers of shingles on a roof? Most building codes allow two layers of organic or fiberglass asphalt shingles on roofs with a 4/12 pitch or less, and three layers on steeper roofs. If the structure can support the added weight, a typical 20-square (2,000-square-foot) reroof will cost at least $1,000 less than a tear-off job.Is it better to remove old shingles?If any areas of the roof have become severely damaged, it’s usually better to remove the old shingles and start from scratch. If you’re going to add a roof on top of an old one, it’s a good idea to remove any loose shingles and apply a new layer of 30-pound roofing felt before laying the new shingles.