Tar Paper Necessary Under Metal Roof

There are pre printed lines on the tar paper that help show you where to end the overlap.

Tar paper necessary under metal roof.

If you have a vertical seam where one piece ends and another starts make the overlap at least 6 inches. The metal roofing system and its expected service life the climate at the building location roof slope and geometry and ambient conditions temperature relative humidity within the building. This thermal break promotes energy efficiency by stopping conductive heat transfer much like the air space between multiple panes of glass in a thermal pane window. Long term in service roof performance can be affected by several important factors including.

Felt otherwise known as underpayment is required when. Roofing felt is a layer of tar paper installed beneath the shingles to provide a backup waterproof membrane in case of leakage. Metal roofing panels rated for architectural use attached to purlins horizontal pieces of wood or metal fastened to roofing trusses are structurally sound when installed according to your roofing manufacturer s instructions and local building codes. Local building codes may specify a certain weight of felt paper but 30 pound paper is usually a good bet.

Metal roofing underlayment is unique in requiring an extra slip sheet layer which is typically red rosin paper. It also creates a thermal break to minimize heat transfer from the roof surface to the structure. Felt paper or not under metal rofing most codes and good roofing practice would require felt. The slip sheet helps keep the metal from sticking to the felt paper while installing the roof.

It provides trapped moisture from under the roof in low slope applications a path to drain. With metal roofing its also a good idea to put a layer of red rosin paper between the felt or ice water shield and the metal that way it wont potentialy stick to it and cause oil canning and would allow for expansion. For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. Sometimes called roofing felt underlayment roofing tar paper or roll roofing this is a layer of protection installed between the roof deck and the roofing shingles.