The average lifespan of a roof covered with asphalt shingles is usually somewhere around 8-10 years, but that time can sometimes become even less than that, depending on the local conditions and weather patterns. You could opt for a different solution than replacing the entirety of your shingle roof – installing a metal roof over shingles instead. Such metal roofs can last a lot longer than the usual shingles and they are not too difficult to install. They mostly require a minimal amount of maintenance at best. The following tips will provide you with the basics of what you need to know to install a metal roof over shingles.
How to Install a Metal Roof Over Shingles
To install a metal roof, you will follow these steps:
Remove the old vents
You should start by removing the old lead boots that cover most plumbing vents. You will also need to remove the galvanized vents as well as the vinyl or aluminum ridge ventilations.
Install the 1×3’s
Metal roofs can bend and become dented if you step on them, so make sure you add some 1×3 spacers on the existing shingle roof. You should do this before you try installing the metal roof over shingles. If you have stripped down the roof down to its bare plywood bottom, then you won’t have to worry about this at all. Start by using 8d, ring shank nails and attach the 1×3’s into the shingles at about 4-6 inch increments. You will need to make sure you cover the main span of your roof, the valleys and ridges as well as the edges as well. You need to make sure you place them right as they will not only serve as spacers but also as deadwood for each of the screws you need to put in. If you have to deal with larger ventilation stacks you will need to wrap a 1×3 box around each of them as well.
Trim the Pieces
Up next comes the installation of drip edge trim pieces. You must attach them with galvanized roofing nails at about 4 to 6 inches apart. You must start at the bottom side of the roof. Then work your way up to the top so you could make a water tight trim with a drip edge. Overlap the pieces at about 2 inches or so so they won’t leak. If you have roofs that pitch less than a 3/12 you should make sure you have more overlapping to ensure they are good enough.
Panel installation
The roofing panels should be attached by starting with the most windy side of the roof. You must attach them with roof screws with a butyl grommet so they won’t allow leaks. Make sure you space the panels and align them properly before you screw them down to the old roof. Add side trim panels and roof peak panels and the vent colors to finish the roof.
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2 replies on “How to Install a Metal Roof over Shingles”
It’s surprising to find out that asphalt shingles tend to last only 8-10 years. I’m very much interested in metal roofing because of it’s longevity. Thanks for your helpful article on installing a metal roof over shingles.
Exactly what I was searching for, appreciate it for putting up.