Roof leak? Call us.(503) 925-0125

The Negative Effect of Multiple Roof Layers

Posted February 29, 2024 by Daniel White
Let Us Help

Key Takeaways 

  • Adding multiple roof layers is a common trick for addressing roof damage and increasing roof durability, but having too many layers can cause issues.
  • The added material on your roof can cause excessive weight and poor ventilation, affecting the structural integrity and longevity.
  • Having multiple layers on your roof leads to other potential challenges like reduced energy efficiency, regulatory issues, and maintenance issues.
  • If you have issues with your roof, it’s always better to address the necessary repairs directly instead of covering them up with additional layers.

Adding a new layer of shingles onto your roof may seem like a quick and simple fix for addressing damage, but it does come with several drawbacks and risks. At the end of the day, there are several reasons why you should steer clear of adding additional layers to your roof.

From potential structural concerns to added difficulty carrying out maintenance, the negative effects of multiple roof layers can add up quickly. Sure, in the short term it can save you time and money to just throw on another layer and avoid any removal fees, but you will likely end up spending more money down the line to make up for cutting corners.


The Issue with Multiple Roof Layers

Adding multiple layers to your roof sounds like a cheap way to repair any damage to your roof, but the risks are not worth it long term. From early wear on your roof to the materials restricting your ability to do necessary maintenance, there are many downsides to adding multiple layers to your roof. 

Structural Issues

Multiple layers of roofing increase the weight considerably. Although each shingle may not seem very heavy, the added weight of the shingles spread out across your roof adds up to several hundred pounds. 

This added weight compromises the integrity of the entire roof, as the structural components are not designed to hold the weight of multiple layers of shingles. Exceeding the weight limits on your roof may require additional reinforcement, as it can stress the structural components and lead to early damage.

This additional reinforcement can be costly, but without the extra structural reinforcement, you risk caving in your roof sublayer and being out of code with local regulations. 

Ventilation Issues

The roof is important for managing ventilation in the home—by adding too many layers, you could compromise the effectiveness of the ventilation and insulation. In theory, additional layers on your roof can provide extra insulation, which can offer benefits by minimizing heat transfer, but a well-installed roof should already provide effective insulating capability with a single layer.

Some of the threats of poor ventilation include: 

  • Moisture buildup that can lead to mold growth
  • An easy environment for moss growth
  • Reduced energy efficiency
  • Lower shingle lifespan

Clearly, the issues that come with poor ventilation are multi-faceted, costing you significant money down the line. The risks of moisture buildup in your roof will slowly add up and wear down your roof.

Then, without proper ventilation and insulation, it could compromise the energy efficiency of your home significantly. The extra layers can lead to trapped heat or cool air, depending on the season.

As a result, you’ll likely end up having to spend more money with your home’s heating or cooling system working overtime to compensate. The excessive heat or cold can also degrade the materials, which aren’t built to manage extreme temperatures.

Shorter Roof Lifespan

The added weight of multiple layers of roofing and improper ventilation can quickly wear down the materials underneath, shortening the lifespan of your roof and requiring replacement sooner.

A roof with multiple layers is not conducive to longevity, especially in wet climates like Portland. Your roof only comes with a single layer for a reason—because it will allow water to run off properly while both protecting your home and providing the proper balance between ventilation and insulation.

There’s a lot more that can go wrong with multiple layers on your roof. Some of these issues include:

  • Reduced wind strength from shingles not having as strong of a hold
  • The risk of rot, insects, mold, and moss
  • Trapping moisture that can wear down the wood underneath the shingles and destroy the shingles’ protective layers
  • The weight of added shingles plus environmental factors like snow and tree debris can pose structural risks

All together, a heavy, poorly ventilated roof will not set you up for success. With the many risks associated with adding multiple layers of roofing, taking this route will simply jeopardize the overall lifespan of your roof. 

Roof Repair & Maintenance Challenges

By adding more layers to your roof, you are doing yourself a disservice down the line. Adding more layers to your roof creates many challenges for future roof maintenance and repair, making it extremely difficult. 

With one layer of shingles, it’s far easier to access all parts of the roof, remove components where needed, and put everything easily back together. Meanwhile, with extra layers, it will be more difficult to identify and address potential issues that arise, like a leaky roof or moss growth.

Some companies may opt not to work on your roof at all because of the potential risks. It can even void previous roofing warranties if you opt to add an additional layer to your roof instead of fixing any issues with the current roofing materials. Even with just two layers, you essentially cut your warranty in half because there is less ventilation and holding power.

Regulatory Issues

When repairing your roof, you also have to consider local regulations surrounding roof construction. Some jurisdictions have set limits for adding new layers to your roof. For example, Portland allows a maximum of two layers of roofing materials. If you attempt to build more than that, you may not be able to receive a permit for your roofing project.

Before considering adding an extra layer to your roof, you should research your local restrictions on how many layers are allowed. When you hire a professional roof repair service, you can trust them to understand local laws and regulations to ensure your roof is up to standard.


Make Your Roof Last Longer with Roof Life of Oregon

Adding multiple layers to your roof may seem like a good idea, but the downsides far outweigh the benefits of a quick fix. The only true way to fix your roof is to address the issues themselves—not just cover them up.

At Roof Life of Oregon, we use our decades of expertise to ensure your roof is in the best condition possible without ever cutting corners. We provide a wide scope of services, from roof inspections and repairs to complete roof replacement. We’ll even perform regular check-ins to ensure your roof lasts as long as possible. 

Schedule a free inspection with us at Roof Life of Oregon. Contact us today to learn more about how we can support you with your roof.

Previous Article
Next Article

Call Roof Life of Oregon Today

If you’re looking for a team that is as knowledgeable as they are kind and proactive, Roof Life of Oregon is the choice for you. Contact us today to experience the difference for yourself.

We’re Here to Help You

A healthy and properly functioning roof, free of moss and debris is also appealing and a source of homeowner pride.

Get a free quote for an inspection today.