Do you need a new roof? Are you trying to save money by nailing over your old roof but need to know if it already has two layers?
I always recommend contacting a professional roofing contractor to get an expert opinion. After all, checking for multiple layers is standard during a roof inspection.
But I understand wanting to know if your roof already has two layers and what it means for your future roof investment. Fortunately, you can figure this out by knowing where to look.
For over 30 years, Bill Ragan Roofing has taken pride in helping homeowners become as educated as possible before their roofing project. So, let’s take a look at how to identify two layers of shingles and more.
By the end of this article, you’ll have the answers to:
- How do you identify two layers of shingles on a roof?
- What issues come with a two layer roof?
How do you identify two layers of shingles on a roof?
The easiest way to identify two layers of shingles on your roof is to climb a ladder and examine the edges, the rakes and eaves. At the eaves (the gutter line), you’ll have to gently lift the shingles and look underneath for another row of shingles.
This is hard to spot without experience because starter shingles can easily be misidentified as a second layer. On the other hand, multiple layers of shingles stand out more on the rakes (the vertical sloped edges of your roof).
You can identify two layers of shingles due to the thickness and stair-step-like appearance you see from the side. Now, I never recommend getting on a roof unless you feel 100% comfortable on a ladder.
Instead, you should look for a less smooth or uniform appearance across your roof. A roof with multiple shingle layers can have ridges, bumps, and/or dips if the bottom layer(s) is too worn, damaged, or already has an uneven appearance.
What issues come with two shingle layers on a roof?
Now, you know how to identify two layers of shingles on a roof. In the majority of the United States, two shingle layers are the maximum a roof can have.
So, if a homeowner is on a very tight budget and only has one layer, nailing over the old roof may be an option. However, this comes with big risks that can lead to costly problems.
Problems with the old shingles didn’t go away
A roof replacement tears off the shingles and components that have reached the end of their lifespan. If you decide to nail over your roof instead of replacing it, you’re just covering up a failing roof system.
These problems don’t magically go away once a second layer of shingles is added. You’re also putting more nail holes in the old roof when installing the new layer.
This is the perfect storm for water to find its way into your home. That’s why you should never consider nailing over your old roof if it’s actively leaking.
Leaks are harder to track and repair
Speaking of leaks, finding one under normal circumstances takes skill to track and repair. However, a second layer of shingles makes it much harder, even for experienced roofers.
If water gets under the new layer, it goes down the old shingles, finds the path of least resistance, and starts leaking inside your home. To fix the leak, it has to be tracked through both layers to find the actual entry point.
This makes it harder to find and increases the chances the roof leak won’t be taken care of the first time. As I said, don’t even consider adding a second layer of shingles if the current layer already has leaks that only a replacement will fix.
Two shingle layers are heavy
Roof decking is the wooden foundation on which your shingles and other components are installed. During a roof replacement, the decking can be inspected after tearing off the old roof and replaced if needed.
Unfortunately, this can’t happen when nailing over an old roof. The problem is, an asphalt shingle roof is already heavy.
So, adding another layer on top of it doubles the weight the decking has to hold. If the decking is compromised, the extra weight can lead to sagging areas and, eventually, structural damage.
Keep in mind there’s no telling how long it would take for a problem to show up, if ever. However, adding the weight of a second layer on decking you don’t know the condition of is a big risk.
Two layers of shingles can create an aesthetic issue
I touched on this for how to identify them, but there’s the possibility that two shingle layers can create aesthetic issues. This is especially true when upgrading 3-tab shingles to architectural shingles.
3-tab shingles run on a 5-inch exposure (you see 5 inches of the shingle out of the full 12 inches), while architectural shingles run on 5 ⅝ inch exposure. This creates a noticeable hump every 8 shingles on your roof.
But remember, adding a second layer over a roof that’s too worn, damaged, or already has an uneven appearance will also create aesthetic problems.
Two shingle layers make a roof replacement more expensive
While adding a second layer may save money upfront, it will make your future roof replacement more expensive. And remember, roofs can only have two shingle layers, so you won’t have much choice.
This greatly increases the debris coming off during the tear-off phase, which means higher labor costs to remove and clean it up. However, the debris has to go somewhere once it’s off your roof.
So, all debris will be loaded into a dump truck or trailer to be taken to a dump of the contractor’s choice. The dumpsites charge significant fees for this service, so the dump fees will be even higher if they have to take multiple loads.
On top of this, there are also added labor costs to actually dump the debris, which gets multiplied the more times they have to make the trip.
What are the benefits of getting a full roof replacement?
After reading this article, you know how to identify two layers of shingles and the problems that multiple layers create. I always recommend getting a full roof replacement instead of adding another shingle layer.
However, talk to a reputable roofing contractor and get honest advice on whether it’s a viable option. But before doing that, it’s important to know what you get out of a full roof replacement.
It’s more expensive but doesn’t have the same drawbacks. In fact, a new roof actually comes with major benefits that only a full roof replacement can offer.
Check out the 7 Benefits of Getting a New Roof to learn what you get when investing in a roof replacement.
