What do you do on slopes lower than 3/12?

Hey out there in roofing land..

Recently I lost a big bid because I suggested using modified bitumen instead of shingles on a low-sloped portion of a homeowner's roof (about 6 squares.) I understand that anything 3/12 and under should not be shingled over.. and that if it IS shingled over, the manufacturer won't warranty it. The customer said that he didn't want bitumen up there because it wouldn't look right, and that he got other roofers saying it wasn't necessary. I happen to think he went with the cheaper quote. What do you guys do on roofs that flat? Any input would be appreciated.

Welcome ,fayetteroofing. Certainteed Winterguard HT is approved as an unerlayment for shingles down to 2/12. I have successfully used it as a low-pitch underlayment for tile many times, although I do it with a system that makes minimal penetrations.

http://www.certainteed.com/resources/winterguardhttds.pdf

Manufacturer's do warrantee it.

Check their specs on line.

3/12 isn't flat.

Manuf. won't warrantee shingles on flat.

To them, flat = less than 2/12

I get the same thing sometimes. One thing you can do if its a 2/12 or better is cover the entire area with ice and water shield and then shingle over it offseting your shingles at least a foot apart if its dimensionals ( this wont help if its 3-tabs as the maximum you can get is 6 inches due to the water being able to enter at the key ways ) The leaks occur on these low slopes by water running horizontally under the shinlges where they butt together if its dimensionals and in the keys and the butts with 3-tabs. ( Its much harder for the water to travel a foot than 6 inches or so.) If their is a slight unlevelness its worse and the water can reach the butt and get under the shinlges from there. It can happen around nail heads also but this is not as common. Also you can go back and seal every nail head and every butt joint with plastic roof cement ( underneath the shingle ). This is a pain in the arse so i guess it depends on how bad you want the job. I also see this problem sometimes on 4/12 to 6/12 slopes as well. The key is a smooth deck surface. So If the levelness of the deck is questionable then you can deck over with plywood or osb to give the maximum levelness. My experience has been that if the deck is almost perfectly level and all other things near perfect as well there is never a problem. Using dimensionals instead of 3-tabs is a big advantage also. Of course there is always the 4 inch exposure as well instead of 5 inch. If its under a 3/12 on one of my jobs its getting shingle grain surfaced modified rubber, period ,regardless of what the home owner wants. If they wont listen to me then so be it. Sometimes your better off passing on a job rather than have a problem a year or two later on down the road. So don't worry yourself to death about "losing" this job. In reality the only thing you may have lost is a huge problem.

PS. We just finished a job a few months ago that was a 4/12 slope. They had about 6 leaks. All in wide open areas of the roof. We took off the existing shinlges and installed GAF Rubberoid Mop Grade. Not a Drop Since! :)

Dimensionals, 4" exposure, and if the owner goes for it, dutch-lap to boot. http://rcs.si-sv2628.com/show_album_photo.asp?userid=30&AlbumID=288&file=1976&s=0

Oh. The one in the pic is 6-8 years old. No trace of a leak.

I really appreciate the response. I am a female salesperson for a roofing company and although I don't actually do the labor, I want to understand the products as best as possible. Tinner666 - what is a dutch-lap? And is that a 3/12 that you put architectural shingles over? Please forgive my ignorance.

I tried to check GAF's specific limit on warranties for low slopes, but all it says is that "For any asphaltic roof system conditions that prevent positive drainage or areas of roof which pond water" are exclusions of coverage. It doesn't specify the slope.. Anyone know where it might say 2/12 or 3/12 has no warranty?

This a job 18 yrs old we did, maybe a 1/12 pitch we ran shingles on 3" lines , with only 30# felt under.......still holding out water today

http://rcs.si-sv2628.com/show_album_photo.asp?userid=148&AlbumID=907&file=6883&s=0

Then along came peel n stick...

Hay willie...you tried any GAF Liberty Cap Sheet,Peel n Stick....man, that mop grade sure is messy..

Hey Pot... That looks like a 2 - 3/12. Everything is usually fine unless some unlevelness develops with the decking. Another cause of the problem around here is fly by nights nailing over an existing roof improperly! As in not doing a butt and run. They cause slight humps all over the roof that damm up the water somewhat during heavy downpours and allow it to track horizontally to the butt joints and leak. Do they make peel n stick with shingle grain surface? Our customers like the low slopes to match the shingled part as much as possible. If they have low slopes we always recommend a color that is available in both the shingles and the modified. :)

fayette...http://www.gaf.com/Content/Documents/50391.pdf

Last sentence of first paragraph @ 4.1.1

All the other mfg co's have similar wording. At that pitch you need to beef up the underlayment. Read all that stuff there. It isn't terribly lengthy and explains a great deal that you will find useful in the future. You have to poke around in the websites looking for this kind of data because THEY are goofy, they think the PUBLIC is goofy, they assume the CONTRACTORS are goofy and so they make the easiest pages to get to the stupid goofy ones. The rest of us who want to make sense of the world have to work harder to find what we need to do that. Good luck with it. Don't worry, the learning curve isn't as bad as it seems at first.

P.S. on that Dutch lap thing...at the risk of ticking off Tinner, who is a very experienced roofer and not someone to ignore if he gives advice, (but...lol) what he means is to take the butt-joints of adjacent shingles and pull one shingle sideways up onto the other one to close that joint. He is the only respectable dude that I know of who will do this and I do not recommend it, nor do I think the manuf. would honor their warranty, at least so far as blow-offs are concerned, if you apply them this way. just my two cents on that one...

Hay Willie , last time i checked , they had 4 colors, white, weather/wood, brown, charcoal. I was told they mite increase the colors in future , maybe already have. The roof in the pics was a 1/12, good and smoothe, but you are rite about the high spots-been dair--dun dat. ;)

Since the death of the low slope shingle we have installed thousands of squares of 3 tab shingles on 2/12 pitch roofs. 68" of ice and water protector at the eaves and 2 layers of felt paper on the remaining roof deck, with the shingles applied normally on top of that underlayment system. This system has worked very well in keeping out the rain. I can't remember a leak that was ever attributed specifically to the use of this system. Being in snow country, we do have some houses that are prone to ice damming. This system does ok in keeping the ice out, but not as good as the original low slope shingle.

You're not going to tick me off Egg. Yes, it's sidelapped, not butted. Manufacturer's rep recommended it. Said it was the same as weaving a valley. My own roof has withstood 70-85 mph winds during a hurricane.

When I was a factory certified installer, they watched me do this one, with their blessing also. I looked at it a month or so ago and it looked good for a 20 y.o. roof. No missing shingles either. http://rcs.si-sv2628.com/show_album_photo.asp?userid=30&AlbumID=108&file=764&s=0