Gaf Torchdown Overtop An Existing One Layer Roof

This provides added protection against ice dams.

Gaf torchdown overtop an existing one layer roof.

Installing a new roof over an existing one also called a layover or nailover is often possible although not always the best option. The installed cost of ruberoid torch granule membrane is less than most single ply systems on the market today. Installed roof designs weigh less than 2 pounds per square foot ruberoid torch granule membrane polyester mat core allows it to resist splits. A two layer torch down roof consists of one base sheet and one smooth cap sheet.

How to install a roof over an existing roof. Two layer torch down roofing may cost less. Single ply membranes such as pvc epdm tpo or torchdown also known modified bitumen are the most common low slope and flat roofing materials. Three layer systems have a base a smooth torch down layer and a torch down layer with a granular surface.

What is a torchdown roofing system. There are many choices and material types you can use on your flat roofing system in seattle. A three layer torch down roof features the same base and cap sheets as well as an additional cap sheet with a granulated surface. Advantages of three layer torch down roofing.

Its core is a strong resilient non woven polyester mat that is coated with weather resistant app polymer modified asphalt. Some roofers install a layer of waterproof shingle underlayment wsu over the existing shingles at the eave end as would be done for a roof laid on bare sheathing. Ruberoid torch smooth membrane is backed by gaf a company with over 130 years in the roofing business. Two layer systems tend to last approximately 15 years while three layer torch down roofing can last 20 years or longer.

There are two different types of torch down roofing systems. A two layer system is made up of one base layer and one torch down layer. Typical system guarantees available for up to 15 years. Depending on your roofing systems design one of these membranes might be a better choice than the other.

However installing new flashings including special drip edge flashings made for reroofing will ensure a tight seal and a long life. Chances are your roof structure was designed for a dead load of one layer of shingles plus extra for snow and a safety margin. The membrane is available with a smooth surface. Installing new roof shingles over old effectively doubles the weight of the roofing so you have to make sure your roof structure can handle the extra load.

Select system constructions available with up to 20 year guarantee coverage 1. Plus learn the advantages and disadvantages of a torch down roof system.