Q: What is the best option for replacing a low-slope roof over an addition? We have a low-slope shed roof that was repaired with roll roofing as an emergency patch in 2014. We had ice damage which forced the roof repair, but because it was in the winter, only the lower half of the 23×12′ area was repaired.
The top half of the addition roof has asphalt shingles where it meets the wall of the main house. Now we are seeing bubbling at the adhesive line (where the roll roofing meets the shingles) and are looking to replace the roof. We live in NH where the weather is cold, icy and often miserably snowy. What would be our best option for replacing the roof? How long does roll roofing last, and are these signs real for needing a new roof? – Linda
A: The roll roofing manufactured today is a very low-quality product that I would not recommend for anything other than a utility shed. The useful life of roll roofing is 5 to 15 years, but it will probably not last 10 years in your climate.
For a low-slope residential roof, there are two main options:
1) Cover the entire surface with a self-adhesive flashing membrane such as Grace Ice & Water Shield (there are many equivalent products). Then apply standard asphalt shingles over the membrane. The membrane will outlast the shingles and seal around all nail penetrations.
Follow the manufacturer’s recommendations for end laps and horizontal laps, typically 3 inches at ends and 6 inches at horizontal laps. The membrane should go up the house wall 12 to 18 inches and be covered by an appropriate counter-flashing on the wall.
3) Where the roof is not visible, consider upgrading to a single-ply roofing intended for low-slope roofs. The most commonly used product on residential roofs is EPDM, which should last for 24 to 40 years or more if applied properly.
In either case, find a professional roofing contractor experienced with low-slope roofs and these specific products. As in all construction work, paying attention to the little details can make all the difference between a long-lasting, trouble-free project and one that results in callbacks and early failure – never a good option with a New England roof. – Steve Bliss, Editor, BuildingAdvisor.com