I have a building with 3 roofs on it, the top layer is starting to curl, etc, due to its age. My question is if having 3 layers of shingles will extend the useful life of the roof? I know this is vague but I hope you see where I'm going with this.
Does a roof with 3 layers of asphalt shingles somehow last longer
roof
Related Solutions
Everyone has given good advice, but the ultimate decision is probably going to depend on the total cost and real time before you plan to add a full second story. I have done dozens of roofs in my time and can give you the following considerations.
A new roof is probably going to cost you around $300 to $350 per square (10ftX10ft or each 100 square feet) for a complete strip, 6 feet of ice/water shield and new 30 yr shingles. Not knowing the size of your roof and pitch, I can't give you a real good guess, but a simple 24X30 cape with a chimney, no crickets or tricky valleys usually runs around 3 to 4 grand. Any good roofer is going to insist that any damaged or rotting roof shiething be replaced while it is stripped, adding more cost. Don't count on using the old roof structure when you remodel. Raising a roof under a new wall system can be very expensive and I suspect you have an original rafter system and board sheithing. Your new roof will want to be of the newest materials and techniques such as trusses, tounge and grove sheathing, soffit and ridge vents etc. A second story is a huge investment and in my humble opinion, very wise to do it all new.
As far as possible repairs to your old existing roof, you may be able to replace some shingles in the field easily, and repair the leaks around the chinmey with a good coat of blind nailing cement or even remove a couple of feet of shingles and treat the area with Grace ice and water shield then reshingle that small area. Obviously, we can't see or judge the general condition or continued life expectancy of the existing roof. I would strongly suggest you stop the water ASAP as Tester is right on saying a couple years of water can cause you a lot of other problems. Good Luck
Replace it now. Like TODAY. That's BAD.
With that kind of bad shingle wear, your shingles are likely to create ice dams which will cause water to back up and leak through the roof, causing interior damage, compounding the cost.
In the summer, the roof won't hold the water because it can't freeze, so the curls will only grab a very little water before it drips free.
In the winter, however, a little retained water will freeze, expand, and capture more water, which will freeze, and so forth.
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Best Answer
No. Layers of shingles on top of each other shorten the life of the roof due to the newest layer sitting on an uneven lower surfaces.
The best life will come from removing all the old layers down to roof boards or sheathing and then laying down the new roof on a well repaired flat surface.
Multiple layers of shingles happen because folks want to avoid extra removal work or to save the cost of removal labor and disposal costs. There is basically no truth to claims of benefits of stacking shingle layers.