Choosing between overlaying new asphalt shingles on top of existing ones or doing a full tear-off depends on several important factors related to the condition of your roof, local building codes, and warranty considerations. Overlaying means placing a new layer of shingles right over the old one, which can save time and money and reduce disposal costs. However, this option is only viable if your existing roof is in good shape—free from curling, broken, or missing shingles, without signs of water damage, rot, or structural issues underneath. You can perform a simple visual inspection by checking for imperfections such as buckling or unevenness. If your roof has more than one layer of shingles already, local codes may prohibit overlays for safety reasons. Also, some manufacturers may void the warranty if an overlay is done, so it’s essential to review the warranty terms before deciding.
If your inspection reveals any damage, water stains in the attic, or a previously layered roof, a tear-off is usually the safer and more reliable choice. Removing all old shingles allows for a thorough check of the underlying decking, ensures proper installation of new materials, and can extend your roof’s lifespan. For a safe DIY check, look in your attic for daylight coming through the roof or signs of moisture, which are clues that you might need a tear-off. When consulting a roofing contractor, ask, “What is the condition of the roof deck after tear-off?” and “How will an overlay affect my shingle warranty?” These questions help protect your investment and ensure you make a well-informed decision based on material condition, local rules, and long-term value.