Same guy- new name - new website!

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Friday, April 3, 2009

Asphalt Roll Roofing for Your Flat Roof

It took all day and several trips to Home Depot, but I finished my flat roof project today. Melinda, from Illinois, asked a question about the best ways to approach a flat roof after I advised against using shingles for this purpose in yesterday's post. The answer is usually based on your budget...

This might be a good time to mention that I'm NOT a roofer. However, I sometimes do roof repairs. I'm hardly an expert on this subject. I found several places online that describe the four main types of flat roofing. The most economical and easy to install is the asphalt roll roofing. Because it was cheap and easy, this was the type of roofing I installed today.

After removing the shingles that had 'doomed this roof to leakiness', I ended up replacing all of the plywood sheathing across the bottom edge. It was all completely rotted and soft. With nearly 4 new sheets of 5/8" sheathing in place, I was ready to clean off the remaining nails and put down 15 lb underlayment. So far, this is the same as a typical shingle roof.

Now, instead of laying shingles, we use asphalt rolled roofing. Each roll covers around 100 square feet, or 1 square (in roofing lingo) and are heavy.

The installation is quite simple. First, I like to unroll a piece and cut it to the right length. Then, I get it in place and nail it along the top edge where the next piece will overlap by around 2-3 inches. The manufacturer suggests that your nails be 9" apart. Once I know it won't move on me, I gently lift up the bottom edge and spread about a 2" line of roofing mastic.

The roofing mastic I was using was Henry's 202. It's actually made for roll roofing so it should do the trick. I spread it with a cheap (disposable) paint brush. Watch out, because this stuff is extra sticky!

That's about it. When you get to the top you want to make sure to get the last roll roofing tucked all the way under the lowest course of shingles. Then nail the shingles like normal to hold the roll roofing there.

They say that this type of roll roofing should last 10 years. Even still, you'll want to keep an eye on any flat roof. They are notorious for good reason.


I still say I'm NOT a roofer! :)


  1. Peter - Thanks for completion entry! Interestingly, the Illinois roof does have asphalt roll roofing on the nearly flat part - so I guess whoever did the roof last did the right thing. I have had leak problems, and still seem to have a spot or two, in the vicinity of the chimney. It's an ongoing process, to be sure! Thanks for the link to our site, as well! I really enjoy your blog!

  2. Thanks, Melinda! Leaks around chimneys or other transitions are extremely common. It may be an issue with the flashing where the seal has been broken and the water's getting through.

  3. Thanks for sharing all this information about roofing.
    Your blog is very impressive and the way you have discribed about roofing is very nice.