Pros & Cons of Multiple Layers Roof Shingles

Pros & Cons of Multiple Layers Roof Shingles. Learn about the benefits and drawbacks of this popular roofing material to make an informed decision for your home.

Table of Contents

• Pros of Layering Roofing Shingles
• Cons of Layering Roofing Shingles
• FAQ
  • Is it OK to put two layers of shingles on a roof?
  • What are the cons to 2 layers of shingles?
  • Is it OK to layer shingles?
  • Is overlaying shingles bad?
  • What is one of the drawbacks to adding a second layer of roofing over a first?

Pros of Layering Roofing Shingles

The pros of layering roofing shingles help the roofer to sell their service to the homeowner:

• Cheaper, faster and less messy; A roofer can pass the cost savings of skipping the time intensive tear-off step and disposal of old shingles to the homeowner; Depending on the size of the roof, this can potentially shave off a day of work for the roofer.

Cons of Layering Roofing Shingles

The cons of layering roofing shingles show how layering roofing shingles is a short-term fix at best, and will result in long-term problems that could be expensive.

• Multiple layers of shingles traps heat between shingles, instead of insulating and moderating its temperature like it should. This trapped heat promotes condensation under the shingles, together reducing the new shingle layer's life in half. 
• Each Layer adds Weight, it's like adding a second or third roof; For example, an average 30 square foot roof requires 90 bundles of shingles. Each bundle weighs about 100 lbs, adding roughly 9,000 lbs of additional weight for each layer. It’s concerning as most residential homes can’t handle this weight; Additional stress on the roof from heavy rainfall or snowfall could cause the roof deck to cave-in.
• Roof becomes Bumpy and Aesthetically Displeasing; Installing new shingles over old buckled or warped shingles will make a roof lose its curb appeal, uneven and bumpy. If the new shingles are of a different size like 3-tab shingles are 5” and architectural shingles are 5 ⅝”, this will result in bumps every 8 shingles. These bumps allow water and wind to get underneath the new shingles, eventually causing leaks.
• Difficult to Locate and Repair Roof Leaks; Finding the source of a roof leak becomes difficult because each layer of shingles can carry water to different parts of the roof before entering the home. Making it difficult to know which one is causing the actual leak, and where else the water is damaging the home. Once located, it will require an expensive repair because it will involve tearing off the old shingles, repairing the roof deck and installing new shingles; There are many risks of putting off repairs on a leaky roof and risks of neglecting your roof maintenance.
• No Opportunity to Fix the Roof Deck; This ignores any damaged roof decking, flashing, and ice and water barriers that need repairs due to not tearing off the old shingles and exposing the roof deck. Allowing any existing leaks or water damage to continue happening without the roofer and the homeowner knowing, until it becomes a real problem for the homeowner.  
• Disqualifies Manufacturer’s Warranty on New Shingles; Disqualifies material warranty, pro rated enhanced warranty and contractor’s workmanship warranty. For example, 3-tab asphalt shingles come with a 25 year warranty, architectural 30 year warranty that’s pro rated 10 years after coverage ends. Further, if a roofer uses all components from one manufacturer the homeowner receives a 50 year non pro rated warranty and contractor’s workmanship warranty.
• Disqualifies Insurance Coverage for Damages; Depending on the provider, any layering of shingles will not be paid for by the insurance company. Reason being, there is an additional cost of labor to tear off each layer of shingles and replace each layer of shingles. 
• Lowers Home’s Value when Selling; During home inspections, multiple layers of shingles on the roof is a red flag (negative) on their assessment of the home’s value because it indicates potential problems for the new homeowner.  

FAQ

Is it OK to put two layers of shingles on a roof?

Yes, it is generally acceptable to have two layers of shingles on a roof, provided it doesn't violate local building codes or exceed your roof's weight capacity. Consult a roofing professional for guidance.

What are the cons to 2 layers of shingles?

Cons of having two layers of shingles include reduced ability to inspect roof decking, potential warranty limitations, possible uneven appearance, and increased weight on the roof structure.

Is it OK to layer shingles?

Layering shingles is usually acceptable, as long as it adheres to local building codes and your roof's structural capacity can handle the additional weight. Consult a roofing expert before proceeding.

Is overlaying shingles bad?

Overlaying shingles is not inherently bad, but it can have drawbacks such as limited inspection access, potential warranty issues, and increased roof weight. Consult a roofing professional to determine if it's the best option for your home.

What is one of the drawbacks to adding a second layer of roofing over a first?

One drawback of adding a second layer of roofing over the first is the inability to inspect the roof decking for damage, potentially leading to undetected issues that could worsen over time.