Can I Use Felt Paper Under Metal Roof

When most people think of roofs they typically think of shingles or metal roofing.

Can i use felt paper under metal roof.

Of course it is a bit more technical than that but this is the basic idea behind how felt works. Make sure the product is designed to be used under metal. 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. Generally speaking roofing felt is a felt paper that is soaked in asphalt and other water resistant compounds to produce a membrane.

Synthetic underlayment is a roofing accessory created by weaving spinning together polypropylene or polyethylene and a polymer to form an all over protective barrier to put between the roofing material and the roof deck. This allows moisture that can become trapped in the roof deck to evaporate and escape. Underlayment must also act as a secondary weather barrier in case the roof fails. 30 felt doesn t come with any kind of warranty as opposed to synthetic underlayment which can come up to a 50 year warranty.

Synthetic underlayment is a newer innovation that is taking over the metal roofing industry as a better more advanced replacement for felt underlayment. The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material. When hot roof construction is done a roof with no ventilation a breathable underlayment is recommended. The temperature under a metal roof can get very hot and over time 30 felt which is composed of asphalt will dry out quickly leaving not much in the way of a secondary weather barrier.

The traditional and most common material used for roof underlayment on a steep slope metal roof is non perforated asphalt impregnated felt underlayment. Most codes and good roofing practice would require felt. For many years roofers used asphalt saturated felt under roofing shingles and it was historically available in two standard weights. Felt is commonly sold in either 15 or 30 rolls measuring 36 inches wide.

What is roofing felt. There are several types of felt underlayment including both organic reinforced and inorganic reinforced. 15 pounds per hundred square feet and 30 pounds per hundred square feet. Traditionally metal roofs have used standard 30 pound felt paper underlayment.