Roof Life On An Overlay

Asphalt shingles can be laid over cedar shakes or shingles however this is a roofing project best left to pros.

Roof life on an overlay.

An overlay roof or the act of overlaying a roof is when your roofer puts a second set of shingles directly on top of your existing roof. An overlay may also be an option for roofs with minor leaks. It is most commonly used as a way to extend the life of a roof and save money by not paying removal and disposal costs of the old roof. If the existing roof has decayed sufficiently it s just not done.

While this isn t the most common method of roofing it does happen especially when homeowners are hoping to save a bit of money on their overall roofing costs. Before an overlay is considered it is vital that you understand that an overlay must be done to the entire roof not just parts of your roof. A roof overlay is the process of adding a layer of shingles and waterproofing over a preexisting roof. When weighing the modest savings against the possible uneven appearance reduced life expectancy and risk of future leaks i would advise against an overlay with new shingles.

Beveled wood pieces called horsefeathers must be laid along the thick edges of the shakes to make a fairly flat surface. More problems with overlay. Find a quality roofing contractor who can assess your roof s condition and do the job correctly. When it s deemed practical a lot of localized repairs to the old roof are often done so that a solid foundation is provided for the new roof.

This isn t perfect though. The design of re roofing specifications follows the same principles as that of new work but there are added complications arising from the need to adapt reuse or overlay existing materials. Before you reshingle a roof read our step by step guide for adding new shingles over old ones. An overlay isn t always possible.

Because of the possible drawbacks of overlay structural problems mainly local building codes may not allow for the overlaying of a roof. When renewing an existing roof consideration should be given to whether or not the thermal performance of the roof should be improved and the impact that may have on detail work particularly abutments. An overlayed roof will also have a shorter life span than a roof of the same material that is applied after a tear off. The double roof will trap extra heat which can warp and otherwise prematurely age the new roof.