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Saturday, February 18th, 2017 by Kevin Marr
A simple enough question right? Besides, what could be wrong with it? Getting a second layer of shingles instead of tearing the old one off and replacing seems to save you money. However, a second layer can actually cost more than a full roof replacement and cause more problems.
Why shouldn’t you install a second layer? If you hire a contractor to put on a second layer then you don’t know the extent of the damage underneath the roof. Many times we find rotten or damaged plywood underneath the old shingles. If we hadn’t torn off the roof, the rotten plywood would have remained and continued to decay. Now many times you can look in your attic and check the plywood to see the condition. Sometimes, however, the plywood only has damage on the shingle side of the plywood and the damage can remain hidden.
Second, if the old roof is not torn off, you can’t install Ice & Water barrier. Building code for Ice & Water barrier is 36” past the wall. This means two or more rows of Ice & Water barrier is required. This requirement is relatively new and many older homes do not have it. Ice & Water barrier is your home's main protection from ice dam leaks.
Third, you won’t get the full life out of the shingle. The second layer isn’t as secure because it has another layer of shingles to penetrate and the roofer does not know if there is any good wood to nail into. Also, the lower layer of shingles traps heat during the day. So the second layer gets baked from the sun above and the first layer below. This is why we see so many shingles that are falling apart. If you go up and touch the second layer of an old roof, the shingle will literally crumble in your hand because of the heat from both sides.
Fourth and Finally, the most important reason not to install a second layer is because the manufacturer will not warranty it. Shingles were never designed to be nailed on top of each other. So the roofing manufacturer will not give warranties to double layered roofs. They don’t guarantee them for the reasons I mentioned above and second layers simply do not last very long.
So in the end, you may get a cheaper roof if you get a second layer but it will only last 10-15 years and it may cause more damage to your home in the meantime. So when it’s time to replace your roof, ask yourself, do I want to do this again in 10 years and do I know for certain that my house is good condition and properly protected? If you don’t know what condition your roof is in then call us and get a free estimate at 1-844-640-9774. Also check out the work we have done in Quinnebaug, West Simsbury, Simsbury, Hartford, Lebanon, Groton, Chester, Higganum, Bozrah, East Lyme, Colchester, Mystic, Wethersfield, Ashford, Mansfield Center, and all over our state.
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