How to Properly Install Roll Roofing

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What You'll Need
Roll roofing
Tape measure
Marking tool
Chalk line
Roofing cement
Galvanized roofing nails
Utility knife

Installing roll roofing is always an appealing option for homeowners because it is easy to install and much less expensive than other roofing. However, roll roofing does not look nearly as good as shingle or tile, so it is typically only used on roofs that are not readily visible. It is a great option for flat or nearly flat roofs since they aren’t visible from the ground, and is a project that you can do in a day. It is durable and will last about the same length of time a typical shingle roof, if not longer -- about six to 12 years. Here you will find the basic information needed to properly install roll roofing.

Prepare the Roofing

Roll roofing is not very pliant or flexible in cold weather of fewer than 45 degrees Fahrenheit and it can crack and break if it is manipulated while cold. If it does have to be installed in cold weather, cut it into 12 to 18-foot sheets and lay them flat inside a garage to warm up and flatten out. It can take up to a day for the sheets to flatten out. If it is warm outside, this should not be an issue.

Install Underlay

While it is not necessary to install an underlay with roll roofing, it is inexpensive and adds a layer of protection that makes it worthwhile. Roll out the underlay and tack it down, making sure that it is flat and smooth, not buckled or wrinkled anywhere.

Install Roll Roofing

Measure 35 inches up from the eaves at several intervals along the roof and mark them. Snap a chalk line as a guide for the first layer roofing; do not use the eaves as a guide instead because they can be uneven. By using the chalk line as a guide, this will ensure that the roll roofing is laid out in a pattern that will make the most of your supplies and ensure you have the most symmetrical and consistent overlaps.

Roll out the first sheet and ensure that it lies flat and even. Apply about two inches worth of cement under either side to seal the roofing down and then nail it down, making sure it still stays flat and even as you go. Once the first row is done, add approximately two inches of cement to the top of the first row to secure the second row of roofing. Continue to stagger the rows as you work with a two-inch overlap on the horizontal seams and a six-inch overlap on the vertical seams. Apply cement at all of the seams and nail down all sheets as you progress, leaving room for about one inch of overhang on each side. Cover hips or ridges last.

Trim Excess Overhang

Using a utility knife, trim away the excess overhang once you’ve finished. Make sure all seams and overlaps are covered with cement, as this will also seal the nails in place.