As long as the plywood under the shingle roof is in good condition this way can provide many benefits.
How to install metal roofing on top of shingles.
Before you install metal roofing repair any damage to the wood under the shingles.
Metal roof over shingles condensation.
Install your metal edging around the perimeter of your roof.
Use 1 1 4 inch.
Install the roofing screws vertically along each rib in the 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.
5install metal panels or shingles.
How to install a metal roof over shingles.
This is by far the most common way to install a metal roof.
By removing the old roof before the new roof s installation you are able to give the underlayment a thorough inspection to ensure there are no damages that could.
Metal roofs must be laid flat on a vapor barrier because steel will condensate if there s any air space underneath it.
Steel shingles weigh about 1 4 what asphalt shingles weigh and aluminum shingles weigh about 1 8 what standard shingles weigh.
This is what it looks like when you install a steel shingle roof system over an existing asphalt shingle roof.
What s involved in how to install metal roofing.
It doesn t matter if the air space is a half inch or six inches because the condensation factor will remain the same.
Be sure the larger edge is laid so that the small edge of the next panel will overlap it.
Codes vary so call your local building department to know how to install metal roofing over shingles properly code wise.
Installing a metal roof over shingles can also result in an increased chance of trapped water vapor and moisture between the new roof and old roof resulting in new mold and rot.
I would say that in most cases less weight is being added to the home by the new metal roof than what the current shingles have lost due to granule wear and oil evaporation.
Experts recommend that you work diagonally and raising each row of shingles gradually.
Align the first metal roofing panel so that it overlaps the edging by 1 2 to 3 4 of an inch and is square to the roof line.
Next use 1 inch nails to secure some metal edging to the perimeter of the roof.
You should start your metal shingles installation with half a shingle or in accordance with your metal shingles installation manual which should be system specific starting from the left of the starter flashing or gable.
Anatomy of a steel roof.
Put the steel down directly on a vapor barrier.
Then cover the entire roof with a layer of insulation and secure it with a staple gun.