Installing Metal Roofing Over Shingles
Is installing metal roofing over shingles a good idea when it comes time to replace your old or leaky roof? The answer isn’t quite as obvious or simple as it may seem. Metal roofing can be a good alternative to a shingle roof. But there are certain pre-requisites to installing metal roofing over shingles. For instance, if your old roof has four or more layers, then this could be a bad idea. Of course, you could meet that requirement by tearing down one of those layers, or even the entire shingle roof.
If you meet the other conditions for installing metal roofing over shingles, here’s how to proceed with the job. First, create a slat board base over the shingles. This can be done by laying boards of 1 x 5 inches lengthwise over the previous roof. Space these boards around 2 feet apart. Attach the framework to the underlying roof with screws.
Next comes the metal edging all along the perimeter. Nail it firmly to the roof using suitable roofing nails. The next step in installing metal roofing over shingles is to attach the metal roofing sheets. These are sequentially attached over a section of the roof, fixing each one to the wooden base with quarter inch screws.
On either side of the sheet, screws are inserted at 2 foot intervals. For additional security, some roofers advise adding a screw in the middle also. Each sheet slightly overlaps the earlier one so that there are no gaps or leaks. Screws will therefore overlap also.
Next in installing metal roofing over shingles is the metal trim. This is applied all along the edges and the top ridge, attached using quarter inch screws placed every 1.5 to 2 feet. It helps to cut the metal with heavy scissors so that it folds over snugly at the ridge.
The free bottom edge of the metal sheet is the only part remaining unattached to the roof frame. These can be connected to the roof with 1/4 inch screws placed 2 feet apart to close the bottom of the sheets. Finally, seal off any gaps or cracks with closures which are self adhesive and keep insects, animals and grime from getting through as well as turning the metal roof waterproof.
Installing metal roofing over shingles can add to the longevity of your roof without incurring the high cost of replacing the older roof after tearing it down. It is inexpensive for this reason and durable because your modified roof will now have two different layers providing cover.
Precautions to take before you start the project to avoid unpleasant surprises is to make correct roofing estimates by measuring your roof’s height and width to determine how much material you will require to complete installing metal roofing over shingles.
To further cut down on your costs, you can apply V-crimp roofing which just bends over the previous roof without requiring lap screws to hold the sheets in place. Before placing the sheets over your roof, when you lean them on the side of the roof, you’ll be able to reach down and pull them up without having to climb up and down each time, saving you a lot of time and effort in installing metal roofing over shingles.