Hello all,I have noticed more and more that the competition is selling Ice&Water Shield to be applied over an existing roof at the eaves and valleys. They are not removing any shingles but applying the Ice&Water then installing the new shingles over it and the old shingles...any thoughts about this? What is the best practice in this situation, I know that it is usually applied directly to the deck on tear offs and new work...Thanks!
No use 90#. I&W over shingles is a waste of an expensive material. Carry a some verification from the manufaturer that I&W over shingles is a no -no. Explain the cost difference. If they are still wanting it done...do it and charge accordingly. Make sure this practice is not covered in you workmanship warranty on said project.
Thanks...but the ice dam problems in the north would be settled by simply adding the extra layer of shingles, or is the risk still there even with the second roof?
as long as it snows, melts during the day and freezes at night there is a chance of ice dams. A second layer won't prevent them, just gives the water an extra layer to work through before you see it coming in.
yeah bad idea. Nowhere does it say use I&W shield over anything but a clean new deck. Id go with the 90# idea.
When shingling over existing shingles the old roof is the underlayment, all you need is something for the valleys.
Installing underlayment over shingles is entirely unnecessary and a waste of money, time, and material.
The only thing that will prevent ice dams is proper insulation & proper ventilation. Ice & water is intended to protect the wood substrate & prevent water from coming into the structure. Putting ice & water shield over the old shingles will do nothing more than protect the old shingles and waste time & money.