As a homeowner in need of new shingle roofing, your roofing contractor will typically give you two choices for the installation. You can either have the existing roofing shingles removed and a whole new roof installed, or you can have your new shingles installed directly on top of the existing ones without removing them. While having the new shingles installed over the old ones is more cost-effective, it's important that you understand why it may not be the best idea. Here's a look at a few of the reasons why you should consider having all of the existing shingles removed when installing a new shingle roof.
One of the most common issues with installing new shingles over your existing ones is the added weight that this results in on your roof. While one shingle by itself may not seem like it weighs much, an entire additional layer of shingles over the ones that are already on your roof can add a substantial amount of weight to your home's roof. Without adequate support, this can cause buckling and other structural concerns due to weight. It's best to keep your roof's weight as minimal as possible, which means removing the old shingles before you install new ones.
Increased Risk Of Damage
One of the things that many homeowners don't consider when they decide to install new shingles over the old ones is the fact that leaving the old ones underneath can increase your risk of roofing issues. If any of the roofing nails on the old shingles back out of your roof, which can happen with any shingles, those roofing nails will then lift up the new shingle that's over the top of them, creating a vulnerability in your roof. When that shingle is raised, even just a little bit, by a roofing nail, it can allow water to seep underneath it. It can also make the shingle more vulnerable to wind damage because wind can get under it and lift it up.
Potential Warranty Problems
Another thing that you should discuss with your roofing contractor is the language of your roofing shingle warranty. Most new roofing shingles come with a warranty to cover premature failure, which is an important feature for your roofing investment. However, in many cases, that warranty will be completely voided if you install those new shingles over the top of existing ones. Make sure that you understand the warranty terms for your new shingles before you decide to install them over your existing roof so that you don't inadvertently void the warranty on your new roofing shingles.
Talk with your roofer about these concerns before you decide whether you should install your new shingles over the old ones or remove the old roofing completely.
For more information, contact a local roofing contractor.