As a roofing expert, I have seen many homeowners consider adding a second layer of roofing over their existing one as a cost-effective solution. While it may seem like a quick and easy fix, there are several drawbacks to this approach that homeowners should be aware of.
The Purpose of Roofing
Before we dive into the drawbacks, let's first understand the purpose of roofing. The main function of a roof is to protect the house from external elements such as rain, snow, wind, and sunlight. It also helps to maintain the structural integrity of the house and provides insulation to keep the interior comfortable. With that in mind, let's explore why adding a second layer of roofing may not be the best idea.Increased Weight
One of the biggest drawbacks of adding a second layer of roofing is the increased weight on your roof.The average weight of a single layer of asphalt shingles is around 250 pounds per square foot. Adding another layer on top of that can double the weight, putting immense pressure on your roof's structure. This added weight can cause your roof to sag or even collapse in extreme cases. It can also put stress on your home's foundation, leading to cracks and other structural issues.
Reduced Lifespan
Another drawback to consider is the reduced lifespan of your roof. A single layer of roofing can last anywhere from 20-30 years, depending on the material and maintenance.However, adding a second layer can significantly decrease its lifespan. The added weight and moisture trapped between the layers can cause the shingles to deteriorate at a faster rate. This means you may have to replace your roof sooner than expected, resulting in additional costs.
Moisture and Mold Issues
When you add a second layer of roofing, you are essentially creating a sandwich with your old and new shingles. This can trap moisture between the layers, leading to mold and mildew growth. Moisture can also seep into the underlying layers of your roof, causing rot and further damage. Mold and mildew not only pose health hazards but can also weaken the structural integrity of your roof.It can also spread to other areas of your home, causing even more damage and costly repairs.
Voided Warranties
If you have a warranty on your existing roof, adding a second layer of roofing may void it. Most manufacturers specify that their warranties are only valid for single-layer installations. By adding another layer, you are essentially altering the original installation and may not be eligible for any warranty claims in the future. This can be a significant drawback as roofing warranties can cover repairs or replacements for up to 50 years in some cases.Additional Costs
While adding a second layer of roofing may seem like a cost-effective solution, it can actually end up costing you more in the long run. As mentioned earlier, the added weight and moisture can cause damage to your roof and other areas of your home, resulting in costly repairs. You may also have to pay for additional labor costs as the old shingles will need to be removed before the new ones can be installed.This process can be time-consuming and labor-intensive, increasing the overall cost of the project.
Aesthetics
Lastly, adding a second layer of roofing can affect the overall aesthetics of your home. The new layer may not match the color or style of your existing roof, resulting in an unappealing and mismatched look. This can also affect the curb appeal and value of your home. While there are some drawbacks to adding a second layer of roofing, it may still be a viable option for some homeowners. However, it is essential to weigh the pros and cons carefully and consult with a professional before making a decision.The Bottom Line
In conclusion, while adding a second layer of roofing may seem like a quick and easy solution, it comes with several drawbacks that should not be overlooked.From increased weight and reduced lifespan to moisture issues and voided warranties, there are many factors to consider before opting for this approach. As a roofing expert, I always recommend investing in a proper roof replacement rather than adding another layer. It may be a more significant upfront cost, but it will save you from potential headaches and expenses in the future.
