How to Install Corrugated Metal Roofing

A worn sheet of corrugate metal roofing.
What You'll Need
Corrugated metal roofing
Tar paper
Closure strips
Metal screws
Waterproof washers

Corrugated metal roofing has been around for a long time. Although you won’t find it used on many houses these days, it’s still commonly used on sheds and garages. Corrugated metal roofing is easy to install but you should make sure you have help when fitting it.

Determine How Much

Before you start to install corrugated metal roofing, you need to figure out how much you need. Measure the length of the roof and the breadth of one side. Multiply those numbers and then double the result for the square footage of your roof. Corrugated metal roofing generally comes in sheets that are 3x6-feet in size (18-square feet). Divide the square footage of your roof by 18 to give you the number of sheets you’ll need.

Lay Tar Paper

As long as the wood on your roof is in good condition, you can go ahead and put tar paper down. Even if there’s older tar paper in place, you should simply rip it off and replace it. Make sure the rolls overlap by at least four inches and staple them into place on the wood. This will help give you a moisture barrier on the roof.

Fit The First Sheet

Get help to lay the first sheet onto the roof. Be sure before you fasten the roofing itself, however, that you lay down closure strips underneath where the screws will go.

The corrugation should run up the roof toward the ridge. Place it at one bottom corner, allowing an overhang of two inches on each edge. Drill a hole in the top corner on the valley of the corrugation, not on the ridge. Fasten into place with a screw and a waterproof washer, going through the closure strip and into the wood. Screws should be placed about six inches apart in all directions. When working along an edge, however, place the screws three inches apart.

Lay the Remainder of the Row

Once the first sheet is in place, you need to install the remainder of the lowest row of corrugated metal roofing. The sheets should overlap by at least four inches - add a bead of caulk where they overlap - and at the other end of the building, ensure there’s an overhang of two inches. Secure the sheets into place with screws.

Continue onto the Next Rows

Place the next row of corrugated metal roofing so that the bottom of it is over the top of the first row. This will help water flow down the roof without running the risk of leaks. Secure the roofing into place as you did with the first row and continue working up the roof, adding row by row until you reach the ridgeline.

Finish at the Ridge Line

As you approach the ridgeline, you need to carefully place the top row to ensure that the corrugated metal roofing doesn’t extend beyond the ridge on each side. Instead, it should come right up to the ridge so that the tops of the sheets on their side are just about touching.

To finish, you’ll need some special corrugated ridge caps. Lay it so it covers the tops of the sheets on both sides and screw in place with screws placed six inches apart, running the entire length of the roof. Do not neglect to caulk the laps on the ridge caps thoroughly or they will leak.