Metal Roof Over Shingles Without Furring Strips

Furring strips are required if you plan to place a metal roof on top of existing shingles.

Metal roof over shingles without furring strips.

Metal roofs depend on thin strips of wood known as furring to allow air to circulate and prevent rot. Use furring strips to build a slat board on the roof then mount the steel sheets to the slat board. Some consideration for vent stacks and chimneys is required during the design process. This is by far the most common way to install a metal 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 can be installed over your existing roof without tearing off shingles provided local building codes allow it. As long as the plywood under the shingle roof is in good condition this way can provide many benefits. If you opt to put the metal roof atop current roof shingles it needs to be done in combination with a synthetic underlayment recommended.

Manufacturers provide 30 year warranties on metal roofing products. My question is before i prep for the metal roof how flat does the roof need to be before i lay down the felt and furring strips. Installing steel roofing over existing roofing materials is fairly simple. There are several spots on the back side missing shingles.

While shingle removal is the preferred route tear off is messy and raises the cost of the job. Screw fasten the purlins using fasteners directly screwed into the trusses or rafters. If talking strip metal roofing like standing or raised seam then i can t imaging getting an even final surface or proper fastening without firring strips not only because putting the metal right on the shingles gives no way to level out the uneveness of the old shingles but also the underlying shingloes and underlayment will get awful hot in the summer without that airspace provided by the firring which should have intermittent air gaps in every row plus generally the screws should. I see all the time that metal roofs can lower energy bills by up to 25 but is that only possible when 1 the shingles are removed or 2 when furring strips are installed over the shingles to provide a gap to allow heat absorbed by the metal to flow under the metal over the shingles and out the ridge vent.

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. It does require certain conditions to be successful however. 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. This should then be followed up with galvanized steel hat channel preferred method or 1 x 2 furring strips.