A thorough inspection of the roof to determine whether the roofing must be removed before applying new roofing should include the following:
1. Check the condition of the rafters and sheathing in the space under the roof. If the rafters are sagging or if the sheathing is sagging between the rafters, the roofing must be removed and conditions repaired before new roofing is applied
2. Check for evidence of leakage into the area under the roof, such as patches of dry rot or fungus or the presence of carpenter ants. If signs of rotting or moisture are widespread, it is best to remove the roofing and repair any damage before re-roofing.
3. Check the condition of the shingle roofing itself. Replace old roofing if it is severely deteriorated or damaged to the extent that the new roofing applied to it would have its appearence or performance negatively affected. However, there are many cases where new shingles can be successfully applied over old shingles
4. If the old roof consists of architectural, lock-type, dutch lap or wood shingles other than sawn quare-butt style, remove the existing roofing, repair decking and/or install new decking.
5. Check whether there is already a second roofing layer on the deck. Building codes in some localities do not permit a third layer of roofing and in any case, it is better to remove the two layers of roofing rather than apply a third layer. Possible problems associated with a third layer include to much stress on the structure, difficulty in fastening through several layers, not enough room under some chimney and wall flashings and reduced shingle life.
Rofers in southern climates tend to avoid roof-over installations. They believe that second roof layers have shorter lives than first layers. Other roofers maintain that it is more difficult to deliver excellent workmanship on roof-over jobs than on clean deck applications.
Contact us today for a roof inspection, we work with individuals consumers, realtors and insurance companies.