Metal Roof Over Shingles Without Furring Strips

If trapped between the metal roofing and old roofing moisture can build up and cause mold and rot.

Metal roof over shingles without furring strips.

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. 1 you said some metal roofing should never have firring strips i have certainly seen that with some of the very thin steel or weak aluminum decking which could never stand even a foot of free span over firring strips without crumpling buckling under someone walking on it so they would have to lie flat on the water barrier over the sheathing. Metal roofs depend on thin strips of wood known as furring to allow air to circulate and prevent rot. Most metal shingles will be attached to the roof using metal shingle clips but metal roofing shingle installation can be system specific.

Consult the guide for your shingle brand to determine the specific method of installation required to preserve the warranty. Furring strips are required if you plan to place a metal roof on top of existing shingles. Manufacturers provide 30 year warranties on metal roofing products. Use furring strips to build a slat board on the roof then mount the steel sheets to the slat board.

But roofers can install a vented metal roof that eliminates this potential problem. Or installing the new metal roofing over furring strips 1 x 3s or similar will raise the metal and provide a ventilating air pocket between layers. This is by far the most common way to install a metal roof. They are compatible with many different kinds of synthetic underlayment.

Spacing of furring strips for metal roof when installing a metal roof over an existing roof insulate the spaces between the wood strips with rigid insulation to prevent condensation before. Some consideration for vent stacks and chimneys is required during the design process.