In general metal shingle systems both stone coated and painted can withstand winds of up to 120 miles per hour.
How to install standing seam metal roof over shingles.
This method has its benefits as well.
As long as the plywood under the shingle roof is in good condition this way can provide many benefits.
If you want to install steel over asphalt your best choice is to use a steel shingle system like the one shown instead of the more common and more expensive standing seam steel.
In contrast steel shingles are small panels installed in horizontal rows much like other shingles.
In a standing seam roof long single panels run vertically all the way from the eave to the ridge.
Unlike steel and aluminum shingles standing seam panels should not be installed over the existing asphalt shingles.
The purlins are screwed or nailed down to the roof deck depending on how the metal roofing manufacturer has testing for their roofing panels and then the metal is installed to the purlins.
The system is designed around the patent pending 138t shingle recover clip and 138t symmetrical standing seam panel.
3 install 1x4 purlins down over the shingles before installing the metal roof the third way to install a metal roof over shingles is by applying 1x4 purlins over the shingle roof.
Snap the panels together and fasten along the opposite side and top of the panel.
Complete and separate roofing systems such as standing seam metal roof systems that are designed to transmit the roof loads directly the buildings structural systems and that do not rely on existing roofs and roof coverings for support shall not require the removal of existing roof coverings.
In contrast standing metal seam solutions can only withstand winds up to 80 miles per hour.
In a standing seam roof long single panels run vertically all the way from the eave to the ridge.
Mcelroy metal has introduced a method for installing standing seam metal roofing directly over asphalt shingles without a tear off.
Better steel shingle systems like the one shown install over a framework of 2x2s.
The main challenges when installing a metal roof directly over shingles with no underlayment are clip alignment and abrasion on the underside of.
Place sealant over underlap rib before sliding hem over the eave trim.
This is by far the most common way to install a metal roof.
The second way to install a metal roof over a shingle roof is with the use of purlins or battens.
There are two main reasons.
Make sure roof is square.