Can Architectural Shingles Be Installed over Architectural Shingles?
Several readers have recently asked me if they can have architectural shingles installed over existing architectural shingles during a re-roofing project. With the growing number of architectural shingles being used today it’s no wonder the question keeps coming up. So in this article I’ll go over this issue and some of my thoughts on the subject.
Re-Roofing Options – To Tear or Not To Tear Off
Re-roofing used to be pretty straight forward with 3-tab shingles. The standard practice was that you could install a new layer of singles directly over the old layer during a re-roof. Most people would limit this practice to a total of two layers of shingles. Any more than that and you’d have to tear off the old shingles before installing a new layer.
Today the question of installing architectural shingles over an older layer of architectural shingles is a bit more complicated and one that doesn’t seem to have 100% consensus.
The answer to the question starts with the drastic difference between an architectural (laminated) shingle and an old school 3-tab shingle. Three tab shingles are a constant thickness while architectural shingles have multiple layers that create an uneven surface. If you look at the picture above you can see the difference.
The quick answer is yes you can re-roof architectural shingles over existing architectural shingles (however you must check with the shingle manufacturer as well). Having said that it will be nearly impossible to get a good looking quality installation. As you can see from the photo the architectural shingles will have bumps created by the old shingles which will keep the new shingles from looking flat and smooth.
Best Solution is Tearing Off the Old Shingles First
The professional answer is no you should not attempt to re-roof architectural shingles over existing architectural shingles. I wouldn’t do it to my home and I certainly would not recommend it to a client. The reality is it would be nearly impossible to get a good look and frankly keep the shingles down flat on the roof and prevent wind damage. I also think that many shingle companies probably prohibit it as well.
For a more professional installation I would highly recommend tearing off the old shingles before installing the new ones. Frankly I’ve yet to see an architectural shingle that needed to be replaced except ones damaged by weather like hail.