The manufacturers themselves will tell you that even the best screws for a metal roof only last approximately 8 to 12 years then you will start to get leaks.
Putting a roof on top of another roof.
Now that we ve taken care of the primary question at hand we ll consider a couple of reasons why you might want to do this.
So if there are already two layers the choice is made for you.
There are two reasons people generally choose to recover their current roof instead of getting a full replacement.
Use a starter strip or cut pieces for a starter course.
As to the ceiling stain in the living room this may have occurred prior to installing the new shingles.
Roofing over your existing roof.
Rip cut the starter strip or starter pieces so that they butt up against the second course of existing shingles and are even with the front edge of the existing roofing.
Also i have to disagree with the statements here that a metal roof will last longer than shingles.
Place the top of each starter shingle firmly against the bottom of the shingle immediately above it and even with the eaves then nail it into place.
Use 1 5 or 1 75 inch roofing nails.
Probably 90 of the metal roofs being put on today are exposed screw metal.
But before we get started one thing must be clear.
If you have serious doubts about the integrity of the new roof a second opinion should be.
The answer is yes you can lay new roof shingles over old ones.
Adding new roofing over old sometimes called a re roof is possible only with asphalt shingles also called composition shingles.
There are already two layers of shingles on your roof most building codes only allow two layers of any type of roofing on your home.
Here are some reasons to do that.
Metal roofing materials are available in several styles that require different fastening applications but are most commonly screwed to the roof framing or sheathing material which in the case of installing over existing roofing material should be fastened using 2 1 2 inch screws.
Attach with nails along the top edge of the strip.
You need to tear off the roof and install a new one.