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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David Starr wrote:
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?

Sure. You can use correctly-applied roll roofing even on really flat
roofs. Your's isn't really flat. It's gently tapered.

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.

kevin wrote:
You need a flat
roof system -- membrane, tar, whatever -- but not rolled roofing.

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.

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.

"David Starr" wrote in message
...
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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Retired Shop Rat: 14,647 days in a GM plant.
Now I can do what I enjoy: Large Format Photography
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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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Retired Shop Rat: 14,647 days in a GM plant.
Now I can do what I enjoy: Large Format Photography
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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).

On 19 Apr 2005 14:31:11 -0700, "kevin" wrote:

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).

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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Retired Shop Rat: 14,647 days in a GM plant.
Now I can do what I enjoy: Large Format Photography
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