Question on 2:12 my re-roof strategy

Woodash · 10-22-2006, 01:48 PM

I am getting ready to re-roof a small part of my house that is ~27ft x 27ft. The area is a low-slope shed-type roof abutting a vertical exterior wall. The roof is mostly over a screened 3-season porch, but with the higher half covering an interior area. Slope is quite low at just a little over 2:12.

Question 1): How far up from the eave do I need to extend waterproof underlayment?

My original plan was to go up 1 or 2 (36") courses from the eave with this leak barrier and then to go with a single layer along each rake. Then, I was going with 2x15# felt and standard 3-tab shingles for the rest of the roof.

Q2): Is the slope so low that I need a full cover of the leak-proof barrier under a layer of shingles? That stuff ain't cheap!

Q3): Forget the shingles and go with the self-adhesive (roll) roofing?

Any info greatly appreciated.

Steve

Woodash · 10-22-2006, 01:51 PM

BTW - I'm in Massachussetts, so ice dam issues are real. And sorry for the dyslexia in the Title....

mdshunk · 10-22-2006, 03:14 PM

Shingles on a 2:12 is a really, really, really bad idea. It will leak.
Consider EPDM for a proper solution.

AaronB · 10-22-2006, 04:24 PM

Although I do not like SA or shingles on taht slope, I would probably go with SA and a whole lot of goop.

if I had to choose between the two.

Woodash · 10-22-2006, 05:05 PM

Thanks for the replys, folks. Just to be clear:

1) A full cover of SA ice/water barrier followed by shingles will most likely leak - correct. CAN THIS WORK, or is my only real choice is to go EPDM, huh?

2) Installation of EPDM is kind of a specialized thing, I imagine. On the one hand, it's cut to fit (presumably in pieces, requiring seams), and then put in place with adhesive. Is this stuff reasonably easy to get hold of and install, or is there something more specialized required?

2) What kind of goop are you talking about and applied how - on top of the SA, or on top of the sheathing?

Thanks once again for any info. I really appreciate it.

Steve

Bonus · 10-22-2006, 11:43 PM

Malarkey makes Arch. shingles that are warrantied down to 2/12 with 2x 15# felt under and the usual w&I eave protection.

AaronB · 10-23-2006, 07:30 AM

Dont do it.

Is that a material warranty? Or a system warranty guaranteeing no leaks?

Some low slope choices include EPDM, modified bitumen, TPO, PVE, BUR, Metal, SPF, polyurea. I am sure there are more.

RooferJim · 10-23-2006, 07:09 PM

they somtimes will shingle a 3in 12 with full coverage of I&W on the whole thing, but a 2 pitch is really asking for problems.

RooferJim
www.jbennetteroofing.com

Woodash · 10-23-2006, 10:17 PM

Thanks for the advice, Roofer Jim. After examining some options, I will do one of the following:

1) 2-ply Elastoflex with a granulated cap,
2) GAF Liberty with base sheet and granulated cap sheet, or
3) metal roof.

I'm not too happy with a 'rubber' roof with a 50-year old black walnut towering above the roof.

Thanks once again.

RooferJim · 10-24-2006, 11:59 AM

Two ply Polyglass Elastoflex is also a good and simple roof to put down,
self stick cap sheet, good laps and 15 yr warranty. I recommend installing when its 40 degrees and rising and using I&W as a base sheet is cheaper and just as good.

RooferJim
www.jbennetteroofing.com

Bonus · 10-24-2006, 07:43 PM

" Is that a material warranty?" It's here on their info for roofs 2/12-4/12

http://www.malarkey.ca/loslope_spec_zone_rightstart.pdf

RooferJim · 10-25-2006, 10:08 AM

Malarky is not available on the east coast. most have never heard of them.

RooferJim

AaronB · 10-25-2006, 01:38 PM

Please do not shingle your 2/12 slope.

If you want the shingle look, check this out. Find a PVC roofer.

http://www.cooleygroup.com/webcont.nsf/0/bldindex

Woodash · 10-27-2006, 12:35 AM

Thanks for the feedback, all. Probably will go the Elastoflex route. And I promise I will not shingle the 2/12, AaronB.

AaronB · 10-27-2006, 07:12 AM

Just for the record, I do not trust SA roofing products. Too many opportunities for failure