How much slope should I put in a roof?

Im at the point where Im getting ready to put a roof on my "awning" in the back yard. Its a 16' x 16' freestandinging gizmo that will cover
my welding Stuff, a place to work on vehicles, and so forth. Lots of similar units around here are flat roofed, but as it appears that we may be getting some rain for the next couple years, Id like to put a small slope on it. How much slope should I put in a 8' span, just to get rid of rain water? 4" 3"?
Gunner
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
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This kind of depends what kind of roofing you are planning to use. The cheapest way is with tin but that tends to leak over time. The next cheapest is roll roofing where you need to torch down the seams. Then you can use comp shingles.
As far as the slope goes, the tin you can get by with a 1:12 pitch The roll roofing with a torch don edge you can go 2:12 or 3:12 for comp shingles give yourself at least a 4:12.
I think I would go with the comp and a 4:12 pitch. Be sure to consider wind load as you have a big sail catching the wind. bolt the sucker down.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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wrote:

My shop is 1/4" per foot. I water leveled it and subtracted 3.75" 15' away. Make it a little more if its not really flat , mine is two layers of 3/4 plywood.
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Sunworshipper wrote:

Do they give away plywood where you live?
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wrote:

They did if you knew where to look before 911. The shop cost about $900. Half of that is just concrete. If there was a natural disaster I'd rather be in the shop than my house. Plywood is down right scary now, I bring home some and the neighbors are like vultures. Matter of fact I took apart 2 garage doors and chopped the metal up like firewood yesterday and the neighbor had to come over to see the old rotten 1/2-" plywood.
Had the drill all hooked up and not one screw would come out so I had to rip the plywood off the screws with a crow bar and two hammers at the same time. That reminds me, I need to put all that in my truck for the dump real soon so my kid doesn't get hurt on all that sharp metal.
Oh, the ole beach tent stakes work good. Dig a hole and put in a horizontal stick and string tied to the middle. Read metal horizontal and cable buried. That way Gunner's roof will never take off.
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On Mon, 24 Jan 2005 12:01:29 -0800, Sunworshipper

Mine will be 3/8" plywood on 2' centers. I scrounged up 8 sheets of 3/8s, just plumb full of staples. I think I can get some rolled roofing really cheap.
So far, Ive got $6 in the project. Not counting the electricity to weld the legs to the support members.
The legs are 3 1/2" oilfield pipe and to the bottom of the beams, is 8', 9"
I wanted 8'...but my buddy cut them a bit long, and I shrugged and welded them up.
Ill post a picture or 2, later tonight in the drop box
Ive got 4 more shorter beams (10') and another 6 or 8 11' joints of 3.5" tubing if I want to make another awning..which I might do to cover some Stuff
Gunner
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
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wrote:

Bet this is why you wanted a drafting machine... Sorry I learned not to sell my first.
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I must be one of those that they make laws that has to have a percentage of the land absorb rain fall or shall we go as far as sun light...
100% no rain would be cool. How about a funnel roof over the entire property and then sell it ! LOL
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On Mon, 24 Jan 2005 15:18:18 -0800, Sunworshipper

Actually no..I never drew a sketch. I had it pictured in my tiny little skull and simply built it the way I pictured it.
Though to be fair..I have had a small bit of experience over the years building things like houses and office/warehouses.
Gunner
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
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I built a house with 6 in 12 and concrete tiles. It got slippery when wet, but I already learned when I sipped off the frozen plywood on the first course.
If I build another, it will be 4 in 12, as I am not as bouncy any more.
Gunner wrote:

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Be careful what you pray for, it can happen.


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I've got a lean-to on the back of the house, and it clears water just fine with a 6" drop over 10 feet.
Dave Hinz
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I should add that this is with steel sheet roofing (the painted stuff with a raised seam every foot; comes in 4' wide sheets). Pole-barn stuff.
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"Standard" roof slopes are 4/12, 8/12 and 12/12. Given you are not dealing with snow loads, I would think all of these would be excessive for your application. Maybe 6"? 3-4" is going to be pretty flat. Not that the extra 2" is going to even be a noticable visual difference. How much rain are you talking about? 1/2" over 2 hours at a time or 2"/hr. A light rain will be more forgiving of the flat roof, but long, hard rains will want a steeper roof to facilitate water removal. Just my thoughts. Worth exactly what you paid for 'em.
JW
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I vote for matching the roof angle on your house. Look better. - GWE
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Depending on your roofing material, minimum slope should be 3 in 12. This is for shingles and a lot of metal profiles. If you go to a 1 1/2" tall rib on a metal profile with sealant tape on top of the lapping ribs, I think you can go down to a 1 1 /2" in 12", but that makes me nervous. Of course, I've always lived in rainier climates.
--
Gary Brady
Austin, TX
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NO SLOPE!!! Everyone should have the wonderfull experience of a flat roof, only better if you were in Ohio.

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On Tue, 25 Jan 2005 03:01:44 GMT, "Tom Gardner"

Chuckle..I made it 4" in 8 feet. Looks pretty good. I simply ran the 2x8 ridge board, then stuck on the plywood. Rain is coming so I did a quick and nasty. Next weekend Ill put in the rafters from below using hangers. It may flap like a sail and leak between the sheets during the week,, but its gotta be better than no roof at all.
Gunner

"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke
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Ijust finished putting up a steel building for my RV. Bought it in kit form. The factory pitch is 1 in 10.
Steve in Daytom
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Don't know how much, but make sure it slopes to the right! <S-EG>
--
Fred R - also in soggy Ohio
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Depends on where you live. Snow starts to melt, run part way down the roof, then refreezes at the edge. Water builds up behind this "dam" and runs under the shingles into the building. In Wisconsin, I'd go with the highest pitch I could afford. Lots of homes were built with 4/12 pitches around here in the 50's and 60's, but they sometimes suffer from those ice dams. Now many are built with 8/12 or more. 12/12 is nice if you can afford it and if someone else is going to shingle it. A high pitch also gives yo overhead storage.
Pete Stanaitis ---------------------------
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