We recently re-shingled our roof. We completely removed 3 layers of old shingles. Papered the entire roof deck, installed roof edge, then shingled with 20 year shingles which we first removed the clear strips over the tar strip. This was done in September on a warm weekend & we noticed the shingles were sticking to each other readily as we laid them. This is what we wanted to happen as cold weather is to be soon here in the Kingston (Ontario) area. While removing the old shingles we noticed most of the shingles were not stuck to each other, the strips did not allow the tar to stick to the lower shingle.
Answer:
The strips of clear cellophane do not have to be removed and on the old ones, they probably were not. You had three layers up there so the strips probably melted away as the shingles aged and then stiffened. The adhesive very possibly just soaked into the base of the shingle as it aged.
