Modified Bitumen Roll Roofing - advice?

toxcrusadr

Omelette au Fromage
Doing a small roofing project, first time for me. I have a small outbuilding with a good pitched roof but it was built by goofuses. For one thing the PORCH roof (about 9x30 ft) is almost flat and they put shingles on it. So the decking is starting to rot underneath, near the gutter.

I was advised by a 30-yr pro to tear it off, fix the rot, and put down stuff that looks like gravel covered shingle but comes in a self stick roll. CertainTeed Flintastic SA is what I got. He said to put tar paper underneath. So I have all that and now I'm looking at instructions from CertainTeed. They recommend "Certainteed Nail Base" on the bottom and then a "mid-ply" layer. Where it meets the higher sloped roof, they recommend using a mastic (theirs of course) to glue down an extra layer of Mid-Ply at the crease. Looks like a type of tarpaper reinforced with polyester or some such. My store does not even carry this.

Here's their install brochure: https://www.certainteed.com/resources/FlintlasticSAResidentialManual.pdf

Install video: http://www.certainteed.com/resident...tlastic-sa-2-ply-and-3-ply-self-adhered-roof/

Questions:

1. Is standard tarpaper (I got the heavy stuff, 32 lb or something) OK for the bottom layer?

2. Do I need the MidPly? Will it make the roof last longer or what? Can I use standard tarpaper for flashing
at that transition? They also show an extra piece at the bottom edge of the roof.

Hoping to get this done this weekend, it may be the last time it's cool till fall.

Any advice greatly appreciated.
 
Manufacturer specs and building codes vary by state and county. (My disclaimer!) I am in Florida. I ran 5 crews up until about 8 years ago when I got outa the biz.
A flat roof ( 0 by 12 pitch) would get a 3 ply roof. s/a base, s/a mid ply, and s/a granulated cap.
Pitched up to 2 by 12, s/a base and s/a cap.
In either case, a nailed 30# felt base is recommended in order to be able to remove the material for future reroofs.
The base layers are installed under the drip edge, The cap sheet is installed on top of the drip edge. All seams are staggered by layer. We were also required to trowel a layer of adhesive on the drip edge under the cap sheet (bull, mule hide, mud, wet and dry, whatever you call it up there). It is recommended to roll each layer, we used a 50 pound roller.
At Transitions to pitched roofs the material would go under that roof about 3-4 rows of shingles. With 2 ply s/a we didn't use flashing at pitch transitions.
Florida is tough on roofs, a 30 year Architectural shingle averages 20 years, low slope roof about 10-12 depending on pitch.

Hope this helps,

Jim
 
OK this roof has a slope, although not a lot, but not flat. Might be as much as 2 inches in 12, maybe as little as 1". I haven't measured it lately. But it sounds like I can get away with not having the mid-ply here since it has some slope.

Just so I'm clear on terms, I have the 30# felt, and the s/a (s/a = self-adhering I assume) cap is the final (granulated) layer...Google is telling me that 's/a base' is a self adhering bituminous sheet that goes in between the two. I think they do have that at my home center, just gotta make sure I have the right stuff.

I'm with you on the staggering of seams and the proper layering, adhesive and drip edge sequence. Exactly how they showed it in the films. They also showed carrying it up 18" onto the steeper pitch.

I might have to rent a roller but that shouldn't be a big deal.

I'm having a call with the pro roofer today so that should help too. Thanks for the advice!
 
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