Can You Lay New Roofing Shingles Over Old Roofing Shingles?

Sometimes, it's tempting to skip steps or cut corners. This is one simple way to save money and shave time off of home maintenance tasks. However, it's not always a good idea. Especially when it comes to your roofing system! Some homeowners choose to lay new roofing shingles over their existing roofing shingles, rather than have the old materials removed first. While it may seem like a no brainer - extra asphalt shingles should mean extra protection, right? - this isn't necessarily the case. There are a number of problems this situation can create.
So, it is time to answer the question: can you lay new roofing shingles over old roofing shingles? Technically, you can. It is possible to apply new materials over old ones and go from there. (This process is commonly referred to as a re-roof.) Before you get too excited about skipping the tear-off process though... wait! Just because you can lay new materials over top, doesn't necessarily mean you should. In certain areas, a re-roof is illegal. If you live in a town or city that is considered a "moderate hail zone" then this process is a no go. It is also not advisable if your asphalt shingles are worn out or in poor condition. As for other roofing materials like wooden shingles, tile, or slate, they cannot be re-roofed.
Knowing there are so many limitations, it begs the question: why do homeowners choose to go down this path? It can be much faster to have a re-roofing project performed than a full removal and installation. A re-roof also means that you don't need to pay out as much money for labour costs since you get to avoid the tear-off stage completely. Saving money can be pretty tempting for homeowners. Every day maintenance costs tend to add up quickly. That means finding ways to cut corners or reduce labour costs is a major drawing card. Unfortunately, this comes with a raft of issues.
While it may seem easier to leave the existing shingles and add new shingles over top, there is still a lot of work involved. Even for a re-roofing project you will need to remove any warped or misshapen shingles, get rid of the vents, ridge caps, and so on. It isn't as simple as just laying down new shingles! In addition, you merely put off having those old shingles removed. The tear-off will still need to be done at some point. A re-roof simply eliminates that problem for a short period of time. This means that you will wind up spending just as much money to have both layers removed in the future.
Here is the reality about laying new shingles over old shingles: it doesn't make your roof more resistant to water or leaks. Even with two layers of shingles, it will not add more protection to your home. If that wasn't enough, the two layers add more weight to your roofing system. This can be problematic if your roof is not designed to carry the extra load. It could affect the structure of the roof and the rest of your home. Other issues? It is impossible to replace the underlaying with a re-roof, this process can affect your roofing shingle warranty, and it can affect the accuracy of your annual inspections.
It is possible to lay new shingles over old shingles - but keep in mind that cutting corners may wind up costing you in the long run. Your best bet? Have those old shingles removed by a professional and choose quality asphalt shingles to replace them. It is the smartest choice for your home.
Joe Davis knows whether or not to lay new roofing shingles over old shingles. He has experience bringing both residential and commercial roofing products to customers all over the country. In the last few years, he has been working successfully with IKO Shingles.