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How Many Layers of Shingles are Allowed on a Roof?

Posted: in Residential , Commercial

A professional roofing crew adds one layer of shingles to a home's roof.Your home’s roof plays a vital role in maintaining the whole property’s structurally sound, safe, insulated, and energy-efficient. However, no matter how durable your roof is, it will have a lifespan of 25 to 50 years, depending on its construction. Over time, you are likely to notice signs of weathering, wear, and tear - which means that it is time to upgrade, repair, or replace the roof!

Since roofing work can cost anywhere between $5,589 - $11,654, it is important to understand how to make the most of your investment. Many homeowners think that adding more layers to the roof will add to the roof’s reliability, safety, and durability. But is this really the case? Learn about the optimal number of shingles layers in this Sherriff Goslin Roofing guide!

How Many Layers of Shingles Should Be on a Roof?

Suppose you have started to notice missing, cracked, or broken shingles on your roof during your roof inspection. In that case, you might consider undertaking a roof renovation project, which is essential to keep the house structure dry, safe, and protected from the elements. In some cases, you might need to replace the entire roof. 

However, if the structure of the existing shingles is mostly intact, you can get away with adding an extra layer of shingles on top of the existing one. This solution allows you to extend the lifespan of your roof in a quicker and more affordable way than replacing the entire structure. The number of layers on a roof is also based on building codes in your area. Contractors can only place a second layer if it's allowed by the local building code.

However, you should not overstep the 2-layer mark! Adding one more extra layer already adds considerable weight to the roof. If you were to try to add a third layer, not only would you potentially be violating building codes, the whole framing structure would need to be strengthened to keep the building safe. No one wants that!

Advantages of Multiple Layers of Shingles

So, now you know that only two layers of shingles are generally allowed on a roof. If a professional roof inspector has guaranteed that the current roof is structurally sound, but some shingles need replacement, adding a second layer to the existing one can help. Here are some of the advantages of this choice:

  • Adding an extra layer of shingles to the existing one instead of stripping the whole roof means significant labor, demolition, and material cost savings. 
  • Adding a single layer can help you extend your roof’s lifespan without major construction works.
  • You can get a new, safe roof for your home in less time - which is perfect if you have started your reroofing project just before winter!
  • Double layers of shingles can help reduce the risk of ice dams.

The Risks of Adding Too Many Layers of Shingles

Most building codes allow for a maximum of two layers of shingles for roofs with a pitch under 4:12 - as far as the roof’s structure is sound, and most of the existing shingles are intact. However, there are some downsides to adding a layer of shingles to your roof instead of replacing the whole structure:

  • If a water and ice shield is not applied in between layers, the whole roof will remain vulnerable to the damage that natural elements can cause.
  • The added layer of shingles might be made of different, heavier shingles that can fill hollow spots. However, these are usually more expensive than standard shingles.
  • The added layer of shingles will inevitably add weight to the roof, which means that the whole roof framing will need reinforcement.
  • Future roof repairs and replacements will cost more because contractors will need to deal with more than a layer of shingles.

Adding more than one extra layer of shingles should be avoided because it can add unsupported weight to the house, causing settling movements and foundation damage - and can affect your warranty!

Choose the Professional Roofing Experts at Sherriff Goslin for Your Roofing Project

Adding an extra layer of shingles to your roof might be a cost-effective roofing solution, but it might not be the best one for all house owners! Make sure to speak to the expert contractors at Sherriff Goslin to find the best solution for your needs. Give our team a call today!