Can You Really Put 4 Layers Of Shingles on a Roof?

Read before you leap – The ins and outs of adding 4 layers of shingles to your roof

If your roof is causing constant problems, it might be time to consider replacing it. However, the idea of investing in a new roof can be scary. Choosing the right materials, finding an experienced contractor, and staying within budget are only a few concerns that keep homeowners up at night.

And when you’re on a tight budget, these worries can be even scarier. You might wonder if you can avoid replacing the old roof and just add another layer of shingles on top. It’s a good idea, but how many layers of shingles can you actually put on a roof? Find out in this blog and make the best choice for your new roof installation project!

New Roof vs. New Layer: What Does the State Say?

  • In many states, safety rules allow only two layers of shingles on a roof. However, you might still come across roofs with three or four layers today.

If your roof already has two or more layers, a contractor will likely suggest a full replacement. Yet, if you can’t afford a full replacement and your current roof has just one layer of shingles, you can consider a nail-over reroof if the conditions are right.

  • Not all roofs are suitable for a nail-over. For it to work, your asphalt roof should be nearing the end of its lifespan, with shingles lying quite flat (no cracks, blisters, or bumps).

Additionally, there should be only a few penetrations, minimal flashing, and no walls pressing against the shingles. Ultimately, your contractor will determine if a nail-over is an option during the roof inspection.

  • Knowing that you’re allowed only two layers of asphalt shingles and that nailing over your old roof is possible, it’s worth noting that this option is generally cheaper than a complete roof replacement.

However, if your current asphalt roof is a good fit for a nail-over reroof, there are important considerations to keep in mind before diving into your project.

4 Things You Must Know Before Opting for a Nail-Over Reroof

Takes Away Access to Roof Decking

  • The roof decking is like the foundation of your entire roof. Usually made of plywood sheets, it’s the layer that holds up all the other roofing materials.

As your roof gets older, it becomes more prone to leaks that can lead to the decking rotting. Here’s the catch: when you opt for a layover instead of a complete roof replacement, you can’t check the decking.

  •  If there’s a problem with the decking, like wood that’s gone bad, it won’t be revealed during a layover. This issue might keep causing trouble until you eventually need a full roof replacement.

If your roof is in the 18 to 25-year range, it might be smarter to go for a roof replacement. This way, any decking problems can be discovered, ensuring your roof gives the best protection for your home.

Impossible to Upgrade the Shingles

  •  When you’re getting a new roof, you have to decide if you want to stick with the shingles you have or go for an upgrade. Many homeowners with 3-tab shingles often think about switching to architectural (also called dimensional) shingles.

But here’s the thing: if you’re upgrading your 3-tab shingle to an architectural one during a nail-over, there’s a little problem with how it looks. This happens because 3-tab shingles show 5 inches of the shingle out of 12 inches, while architectural shingles show 5 ⅝ inches.

  • This difference in size creates a kind of bump on your roof every 8 shingles. So, if you’re planning a nail-over, you will have to opt for the same asphalt shingle you already have to avoid this issue.

Problems with Roof Flashing Will Persist

Roof flashing plays a crucial role in keeping water out of your home. It’s basically a metal sheet that goes around things sticking out of your roof, like vents or chimneys, making sure water can’t sneak in.

  • When you’re just adding a new layer of roofing without taking off the old stuff, you can’t replace the old flashings. If those old flashings are already leaking or were put on poorly in the first place, you will eventually have to bear the cost of neglecting roof repairs.

In such cases, it might make sense to go for a complete roof replacement. It could save you money in the long run by preventing constant repairs. When you get a cost estimate, the salesperson should check the condition of the flashings to see if they need attention.

Disqualification from Best Material Warranty

  • layers of shinglesChoosing to upgrade your shingles not only results in a bumpy roof but it also means missing out on the chance to snag an improved warranty when nailing over your old roof. Every batch of asphalt shingles comes with a warranty straight from the maker.

The 3-tab kind comes with a 25-year warranty, while architectural asphalt shingles have a 30-year warranty that starts to go down after 10 years (coverage decreases over time).

  • However, if you use all the roofing stuff from one maker for your roof replacement, you can grab a sweet 50-year non-prorated enhanced warranty. Even if you opt for architectural shingles for your nail-over, the enhanced warranty won’t be an option.

Your contractor’s warranty for their work remains the same, but you’ll only have the regular material warranty for your architectural shingles.

When it comes to building a new roof or replacing an old one, many people try to avoid a full teardown to save time and money. However, piling on multiple layers of shingles might seem like a quick fix, but it can lead to more problems and end up costing a hefty sum down the road.

That’s why it’s crucial to consult with your contractor before making a decision. If you’re on the lookout for skilled professionals to guide you through this process, reach out to us at Dupont Roofing today. Our experts can inspect your current roof and help you figure out the best solution. Give us a call at (202)840-8698 or fill out the form on our website to set up a free consultation!

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