Do you need a new roof on a shoestring budget? Are you considering nailing over your current shingles with new ones?
Buying a new roof isn't fun. It's expensive and you don't necessarily get to use it.
So, I understand some homeowners try to save money where they can. And one of the most common ways to do this is to nail over your old roof.
However, roof can only have a certain number of shingle layers before a full roof replacement is required. On top of that, there are some major things to consider before nailing over old shingles.
For over 35 years, Bill Ragan Roofing has prepared homeowners for their roofing projects with honest and transparent advice. So, let’s break down the number of shingle layers a roof can have and much more.
By the end of this article, you’ll learn the answers to:
In the United States, you’re only allowed to have two layers of shingles on a roof for fire safety reasons. So, you’ll need a full roof replacement if you roof already has two or more layers.
But even if there’s only one layer, nailing over isn't recommended. In fact, most roofs won’t even be in good enough shape to do it.
Not only do the shingles themselves must be almost flat (no lifted or cracked shingles, blisters, or bumps), the roof must also have few penetrations, small amount of flashing, and no walls that butt up against the shingles.
Ultimately, it’s up to you and your roofing contractor to determine if nailing over your old shingles is a good idea. However, it's crucial to hire a reputable local company to ensure you get honest advice.
As I said, most roofs won't be a good fit for a nail-over reroof. Any reputable roofing contractor will recommend a full roof replacement 99 times out of 100.
However, it's your roof and money, so it's really up to you. That said, nailing over old shingles comes with major drawbacks.
Let’s look at the following things to consider before nailing over your old asphalt shingles:
Roof decking (also known as roof sheathing) is the foundation of a roof system. During a full roof replacement, your roofing contractor can inspect the decking’s integrity to see if it can handle your new roof after the old one is torn off.
Because the tear-off process is skipped, inspecting or replacing your decking when nailing over your old shingles can’t happen. This may not seem like a big deal, but rotten or compromised decking leads to structural issues and even potential health hazards.
That’s why a reputable roofer will always recommend tearing off your old roof.
An asphalt shingle roof is heavy as is, and adding another layer doubles the weight. If the decking’s integrity is compromised, it may be unable to handle the weight of the second layer of shingles.
The fact that you can’t check the decking beforehand increases the risks even more. Now, there’s no telling how long it would take for a problem to show up.
However, the weight will cause sagging and eventually lead to structural damage that creates the potential for your roof to cave in.
Roof flashing is a crucial roofing component used that prevents roof leaks in areas where shingles go up against something, like walls, a chimney, or open valleys. I always recommend replacing your old roof flashing when getting a new roof.
However, getting a second layer of shingles means your roofer has to rely on someone else's workmanship and use your roof’s current flashing. Unfortunately, you’ll be dealing with big problems if the metal’s integrity is compromised, rusted, or the flashing is poorly installed.
This means spending even more on repairs and replacing the flashing down the road anyway, which isn't cheap. That’s why you must ask your roofing contractor if they saw any problems when considering adding a second layer of shingles.
The whole point of a roof replacement is to replace roofing materials and components that have reached the end of their lifespan. Like roof flashing, the other components and materials won’t get replaced when adding a second layer of shingles.
However, not replacing crucial materials and components isn’t the only problem. The main issue is the second layer of shingles covers up existing problems on a failing roof system.
These problems don’t magically go away and are still there if water gets under the new layer of shingles, which takes us to the next point.
Finding a roof leak takes skill to track and repair under normal circumstances on an asphalt shingle roof. Unfortunately, adding a second layer of shingles makes it much harder.
If water gets under the new layer, it goes down the old asphalt roof, finds the path of least resistance, and starts leaking inside your home. This makes it harder to find where water is coming from and then repair it to ensure the roof leak is taken care of the first time.
That’s why you shouldn’t even consider nailing over your old roof if it already has leaks and other problems only a replacement will fix.
All asphalt shingles come out of the package with material warranties from the manufacturer. The good thing is that this doesn’t change when adding a second layer of asphalt shingles.
However, you can’t qualify for the 50-year non-prorated enhanced warranty on the entire roof system because you didn’t install the other required components. Manufacturers simply won’t warranty a roof system that doesn’t have all-new roofing components.
This means any problems or roof leaks with a two-layer roof will have to be taken care of by your roofing contractor’s workmanship warranty. Unfortunately, a roofer most likely won’t offer anything long-term because of the high potential for problems down the road.
During a standard roof replacement, your old shingles are torn off down to a clear roof deck. Once it’s torn off, all that debris will be loaded into a dump truck or trailer to be taken to a dump of the contractor’s choice.
But if your roof has more than one layer, there's much more debris coming off your roof. This not only increases labor costs but also the dump fees when getting rid of the torn-off materials.
So, you may save money at first when nailing over your old roof, but you'll have an added cost to remove that layer when getting a new roof in the future.
Ok, let's say a roofing contractor recommends nailing over your old roof. If you're in dire need of a new roof and money is very tight, a nail-over may be an option to get you by.
However, bad roofers will do it anyway to make easy money, even if the situation isn’t right for a nail-over reroof. As soon as you mention you're looking for a nail over, they'll have no problem taking your money and doing sub-par work.
And remember, you most likely won't get a decent workmanship warranty. After all, nailing over an old roof is pretty much just kicking the can down the road and they won't want to deal with the problems.
After reading this article, you know a roof can have two layers and what to consider before nailing over your old roof. It may be an option if your current roof is in decent enough shape and you’re in a tough spot financially.
The important thing is to talk to a reputable roofing contractor and get honest advice on whether a nail-over reroof is a viable option. But as I said, most homeowners will need a full roof replacement.
It will obviously be more expensive, but it doesn’t come with the same drawbacks. In fact, a new roof comes with more benefits than you may think.
Check out the 7 Benefits of Getting a New Roof to learn what you get when investing in a roof replacement.