roof pitch

wanting to build onto side of barn will be 12 ft high at highest point how low can i go at 14 ft out and be safe i live in pa thanks

8'

The answer is- It depends. I assume it's snow load you're worried about. Is it metal or composition roof? What are your rafter dimensions and what is the rafter spacing?

it will be 2x6 rafters with osb roofing

rafter spacing will be 2 ft on centerthanks

rafter spacing will be 2 ft on centerthanks

Forget the OSB and shingles and go with a steel roof.

Gordo

You've got to be crazy if you're talking about a 14 foot span and only using 2" X 6" rafters. You said 14 feet, but I'm not sure it that's 14 feet of span, of maybe 12 feet on the outside wall and another 2 feet of overhang.

A standard (pine or spruce) 2" X 6" can span 10 feet at most for a moderate snow load (30 psf), and that's when spaced on 16" centers. If 24" it's only good for 9 feet of span in light-snow areas.

In my area of central New York, a roof must be rated at 60 psf snow-load. A 14 foot span requires 2" X 12" rafters if spaced on 24" centers and 2" X 10" rafters if on 16" centers. Further north in the Adirondacks, an 80 psf is required.

Pitch has nothing to do with any of that. Pitch determines how many leaks you're going to have - or - how much snow will build up without shedding itself clean. Also if the roof is too flat, many types of roofing, including steel, will leak. I wouldn't build anything with less then a 3/12 pitch, and only then if someone is going to be around to shovel snow off of it. 3/12 pitch on a 14 foot span, starting at 12 feet high, is going to be 8 1/2 feet at the low side. With that 3/12 pitch, you can use steel roofing if you do it right. Any flatter and you're going to have leaks.

Well said!!

I built a lean-to on the west side of my barn 15+ years ago. It has a 2.5' to 12' pitch with three tab shingles. In shingling it I used seven gallons of additional tar to improve on the factory seal tabs. I also used four nails per shingle. Roof has worked out perfectly with heavy snow loads and does not leak a drop.

Building is 16'x30' with a 3' overhang (rafters are 20' feet long. 1 foot of the rafters rests on the existing barn wall.) Rafters are 2x12" spf on 24" centers.


Glenn F. (NE WI)

I would go with a 4/12 pitch , and a pre-enginered half truss. By the time you buy the rafter material, and make one or two oversights, you could easy pay for trusses. And they are easy to put on.

No roof load ratings in my area and no building codes or permits required for farm buildings. That said in the 70's we built on the side of the barn 20' wide and had to use 22' rafters and they are 2 X 6 on 16" centers with 1 X 4 sheating spaced 8" between with steel roof and pitch if possibly at most 3-12 with no problems yet and we do get heavy snow loads, never shovel a roof, and some mighty strong winds. Few years later built shed on end of barn, 18' with 20' rafters (22' not avaible) 1/2" plywood sheating and shingles, pitch is just slightly more as top height and bottom height same, just 2' narrower and rafters holding up good. Had to replace shingles once.

I know I'm going to get beat up, but here goes. I have 2 leanto's on my property(South East MI). One off the back of the garage (12'x22'), that was put up 25 years ago as a temporary structure, and is now a roof for a back porch. It has 15" of pitch in 12' with snow and ice shield and 3 tab shingles. It has double 2x4 rafters (16" on center) set on a 2x10 @ 10'. Because there is no heat under it, snow has never been a problem. The other is off one of the barns. It is 8 years old and 13'x48'. It is 2x8 16" on center set on a 2x12 @ 13'. 18" of pitch with snow and ice shield and 3 tab shingles. Snow load the same as above. I know there not to speck, but don't hold your breath waiting for them to fall down.

Asphalt shinges are crap.My next job is steel.