Is it always necessary to tear off existing shingles before reroofing?
There are two options available for reroofing installations. One would be to tear off the old roof before applying the new one (tear off). The second would be to lay new shingles over the existing roof (lay over). While the second choice is the less expensive of the two options, it is not necessarily always the best choice. There are advantages to tearing off the old roof before installing a new one. For example: • If there are any defects in the roof deck, they will be revealed when the roof is torn off. These defects should be repaired before applying the new roof. • If condensation problems exist in the attic, they too will be revealed when the roof is torn off. Properly designed attic ventilation can then be installed in order to help eliminate such problems. • When the old roof is torn off, waterproofing shingle underlayment can be installed before applying the new roof. This will help protect against cyclical ice damage. • Tearing off the old roof and starting with a clean deck b
