Metal Roof Installed Over Shingles With 1 Board Underlayment

Concerns with metal roofs.

Metal roof installed over shingles with 1 board underlayment.

Asphalt shingles can weigh up to four pounds per square foot depending on the brand. Because metal roofs are so light yet so strong metal roofing panels can typically be easily installed over your existing asphalt roof shingles without the need to add structural reinforcement. As long as the plywood under the shingle roof is in good condition this way can provide many benefits. Make sure the product is designed to be used under metal.

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. For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. Synthetic underlayment is a newer innovation that is taking over the metal roofing industry as a better more advanced replacement for felt underlayment. In some areas building officials only allow a re roof over one layer of shingles.

It serves as a moisture barrier as well as a slip sheet. Once again this is used on cold roof construction. We recommend a polypropylene scrim reinforced underlayment made up of multiple layers. Metal roofing comes in numerous styles that mimic modern architectural shingles unique clay tiles traditional standing seams metal roofs with panels that run vertically up the roof charming wood shakes and more.

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. Yes you can install a metal roof over shingles. This is by far the most common way to install a metal roof. 3 install 1 4 purlins down over the shingles before installing the metal roof the third way to install a metal roof over shingles is by applying 1 4 purlins over the shingle roof.

Building officials in some areas will only allow a re roof over one layer of shingles while officials in other places may allow you to place the roof over two layers of shingles. Moisture can infiltrate the underside. However you ll want to check with your local building department before you make any decisions. This type of underlayment is critical to a quality roof installation.

A metal roof under the same conditions may stay more than 50 f cooler than an asphalt roof which saves both energy and money. Many metal roof problems are due to moisture.