Underlayment for porch roof

tummyman · 07-28-2021, 01:06 PM

So what material is on it currently (three tab, roll roofing, etc...???)? How long has it been down? Maybe your answer is right in front of you....with a good ice and water membrane like Grace.

John Mercier · 07-28-2021, 06:26 PM

You don't use Grace under rolled roofing.
It would void any warranty.

Low slope is either going to require GAF Liberty *the brand she wants* or EPDM rubber roofing.

GAF Liberty is listed as going from 1/2:12 to 6:12, and should be applied as recommended.
https://www.gaf.com/en-us/document-l...structions.pdf

SailinAway · 07-28-2021, 08:19 PM

Quote:

Originally Posted by tummyman

So what material is on it currently (three tab, roll roofing, etc...???)? How long has it been down? Maybe your answer is right in front of you....with a good ice and water membrane like Grace.

Two or three layers of rolled roofing. Ancient.

SailinAway · 07-31-2021, 08:45 PM

Now the roofers disagree about the slope. One said 1.5-2; another said 4. Any way to measure it?

John Mercier · 07-31-2021, 08:59 PM

Quote:

Originally Posted by SailinAway

Now the roofers disagree about the slope. One said 1.5-2; another said 4. Any way to measure it?

One foot of run horizontal, measure the rise in inches.
There is also some inexpensive tools made that measure the angle and transfer it to pitch.

07-28-2021, 01:06 PM	#1
tummyman Senior Member Join Date: Aug 2009 Location: Moultonborough Posts: 833 Thanks: 256 Thanked 672 Times in 243 Posts	So what material is on it currently (three tab, roll roofing, etc...???)? How long has it been down? Maybe your answer is right in front of you....with a good ice and water membrane like Grace.

07-28-2021, 06:26 PM	#2
John Mercier Senior Member Join Date: Jun 2021 Posts: 3,369 Thanks: 3 Thanked 594 Times in 490 Posts	You don't use Grace under rolled roofing. It would void any warranty. Low slope is either going to require GAF Liberty the brand she wants or EPDM rubber roofing. GAF Liberty is listed as going from 1/2:12 to 6:12, and should be applied as recommended. https://www.gaf.com/en-us/document-l...structions.pdf

07-31-2021, 08:45 PM	#4
SailinAway Senior Member Join Date: Apr 2019 Posts: 991 Thanks: 256 Thanked 280 Times in 169 Posts	Now the roofers disagree about the slope. One said 1.5-2; another said 4. Any way to measure it?

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SailinAway (08-01-2021)