Really flat garage roof

Looking at my garage roofline from the side, the front 1/2 is an inverted "V". The rear half is flat with a 1.5-12 pitch. The roof is rafters, not trusses. Is that rear pitch sufficient for roll roofing? The front is no problem; it's a 4-12 or 5-12 pitch.
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Um... not so sure here. 1.5 in 12 pitch is considered "flat" by code, my local inspector tells me. If you mean regular rolls of shingles (~ 3ft wide, nailing strip at the top, some tar near the bottom, etc), then no, you can't use it. Or, well, of course you can do whatever you like.
Roll roofing needs a pitch to work. It can be less than for shingles, but certainly not flat.. 1.5 might as well be flat -- the slightest little backup of water, snow, or ice, or a little wind, or a slight bubble or crease or whatever, and water will back right up under the rolls and into the garage. Milage will vary depending on climate (snow? driving rain?), and if you garage is heated. You need a flat roof system -- membrane, tar, whatever -- but not rolled roofing.
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David Starr wrote:

Sure. You can use correctly-applied roll roofing even on really flat roofs. Your's isn't really flat. It's gently tapered.
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I have used "Modified Bitumen Torch Down" roofing on low slope with very good results. Also rubber membraines or others may be good also. Not "rolled roofing". Although torch down comes in rolls I suspect its not what you are talking about.

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kevin wrote:

Kevin is right... I don't know what my mind was saying. You do need to treat this as if it WAS a flat roof. A complete sealed underlayment system is in order.
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I appreciate all the answers I'm getting. The present roof is 1/2 lap roll roofing; 1/2 stones, lap each course to the stones. This lasted 20 years. I can steepen the pitch, but that would require 16 foot 2x8's or 2x10's for new rafters, plus all new sheathing. Not sure what I'll do yet. I'll look into the torchdown as well.
Thanks to all who replied.
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20 years? In that case I'd be real tempted to just do whatever was done last time. Your climate etc. must be right for rolled roofing. Besides, it's over a garage, so an occational leak (during a bad storm or something) wouldn't really be a big issue anyway.
Here on a 2 over 12 pitch on our dining room we get constant leaks, with all sorts of terrible degredation on the roof. And its only 3 years old! (from the previous owner -- we are putting in membrane this summer).
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That's what I've decided. I'll strip off everything down to the sheathing (there's 2 layers), replace the bad sheathing & reroof the same way it was.
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