How to Add a Roof over Asphalt Shingles

What You'll Need
Pine sheeting
Metal roofing sheets
Metal roof edging
Metal roof trim
Galvanized roofing nails
Wood screws
Lap screws

While asphalt shingles are a cheap, popular and low-maintenance type of roofing, many people are turning to metal roofing for its extra strength and durability. Metal roofing is used in many applications and is becoming an increasingly popular alternative to a shingled roof, whether the shingles are made from asphalt or other materials. To save a great deal of time and effort, a metal roof can actually be installed over asphalt shingles in most cases. Since you will not have to remove the original shingles, the job can be done much quicker without as much labor required. If, however, there are already 3 or more layers of shingles installed on your roof, these will still need to be removed.

Step 1 – Install the Base

First, you will need to install a base for the metal sheeting. Make a line of slats and boards from the pine sheeting, and install this on top of the shingles. For every 2 feet of the roof, you should install 1x4 inch pine boards along the length of the roof. Start at the bottom of the roof and work your way to the top of it. Use some 3-inch wood screws to attach the boards in place.

Step 2 – Install Metal Roof Edging

Install the metal edging around the entire perimeter of the roof. Nail this edging into the roof using galvanized roofing nails. Place these along every six inches of the metal roof flashing.

Step 3 – Install the Roofing Sheets

Install the metal roofing sheets one by one. Start from one side of the roof, working your way to the other. Start from the top and work towards the bottom for each section of roofing that you install. Roofing nails should be used to fix the metal sheets to the pine slats beneath. The screws should be placed in the center line of the first section as well. The next section of metal sheeting will overlap the previous one. Follow the same pattern until you get to the other end of the roof. When the roofing sheets have all been installed, use lap screws every four feet where the metal roofing sheets overlap.

Step 4 – Install the Metal Roofing Trim

The metal roof trim will also be installed around the edges of the roof. This trim will give the roof a finished appearance. Bend the trim neatly over the edge of the roof as you install it. Use roofing nails to attach the trim in place.

Step 5 – Install the Closures

The closures are important for helping to protect the roof from any animals which may try to get in and from driving rain. Closures are self-adhesive and should be pushed into the openings around the roof. They will seal themselves. Finally, your roof is complete and should last many years with minimal maintenance.