32x40 w/Shed Roof?

[MAINEGUY]

Hello I am new to posting here but have been researching here since I joined. I am in the process of building a 32x40x12 stick framed garage. The structure will have 12' walls on top of my already poured 5' frost wall foundation (~1' exposed above grade). The building will have 3 10'x10' overhead doors across the eve (40') side of the building. Living in Maine one of the concerns I have with a standard gabled roof truss system is the snow shedding off the roof in front of the doors. This of course is with the trusses spanning the 32' side as spanning the 40' side would add too much cost to the trusses required. What i was thinking of doing instead is a have a shed roof truss built to span the 32' pitching 5/12 to the back of the building. I would essentially eliminate the snow shedding in front of my doors and I think 5/12 with a metal roof should shed the snow just fine.

Anyone out there have this size building with this roof design or any other thoughts?

Thanks
Eric

 

[Voi]

Hello I am new to posting here but have been researching here since I joined. I am in the process of building a 32x40x12 stick framed garage. The structure will have 12' walls on top of my already poured 5' frost wall foundation (~1' exposed above grade). The building will have 3 10'x10' overhead doors across the eve (40') side of the building. Living in Maine one of the concerns I have with a standard gabled roof truss system is the snow shedding off the roof in front of the doors. This of course is with the trusses spanning the 32' side as spanning the 40' side would add too much cost to the trusses required. What i was thinking of doing instead is a have a shed roof truss built to span the 32' pitching 5/12 to the back of the building. I would essentially eliminate the snow shedding in front of my doors and I think 5/12 with a metal roof should shed the snow just fine.

Anyone out there have this size building with this roof design or any other thoughts?

Thanks
Eric

If I'm following this correctly you'll have 13' tall sidewalls then a single slope (aka skillion or shed) roof on top of them?

If so, at a 5:12 that will put your front eave over 26' tall. I'm not so sure that won't add expense equal to or greater than running gable trusses over the 40' length.

Were you wanting to do this with parallel chord trusses for a completely open space/ceiling or do you mean a truss with a bottom chord parallel to the floor and therefore a flat ceiling?

 

[Voi]

This is what I meant by a parallel chord truss. I'm sure for a 32' span you'd have to do something like this or a similar wood/metal hybrid if you wanted a mostly open space inside and cathedral ceilings.

And this is what I mean by a truss with a bottom chord parallel with the floor. This would be for a flat ceiling at your sidewall height.

 

[lakeroadster]

That would give you a nice loft space if the truss was designed for attic storage. And as shown in the photo above that VOI posted, assuming the building is oriented correctly, you could get some excellent thermal advantage from the sun also.

How would that look in comparison to your other buildings on the lot?

The other down side is if you get drifting snow... with that height... huge drift in front of the building right where you don't want it.

On our 30 x 40 barn, oriented similar to yours, we simply added snow trim to the roof across the side of the building with the doors. It does a great job of not allowing the snow to slide off the roof. Same concept they use at ski resorts.

The kicker to the snow trim is the trusses need to be designed for them. The loading on the roof is increased due to higher snow loading.

 

[MAINEGUY]

I'm sorry I forgot to halve the traditional pitch. I meant a shed roof truss, bottom cord parallel to the floor with a 2.5 pitch. With a 1' overhang on each end (34' Truss) this would make the building approximately 20' at the front of the building. Correct?

As far as other buildings around there won't be any. I own two lots totaling around 13ac and am 1000' off the main road.

Honestly I own 4x4 backhoe so clearing the snow that would shed in front of the building shouldn't be a problem for me now at 46, but I might not always feel that way.

 

[matt_i]

I think you could probably save money if you bought a standard triangled roof truss with 5:12 pitch. Snow is not going to shed from a shingled roof in my experience, other than fluffy stuff which drifts in high winds. Metal roof is of course different but there are clips that go on the ribs or glue to the flats which help retain snow and prevent people underneath from getting wrecked to the ground by a falling avalanche.

 

[Voi]

I'm sorry I forgot to halve the traditional pitch. I meant a shed roof truss, bottom cord parallel to the floor with a 2.5 pitch. With a 1' overhang on each end (34' Truss) this would make the building approximately 20' at the front of the building. Correct?

Yes, around 20' depending on depth of top chord, thickness of roofing material etc.

Speaking of roofing material, we are building a single slope roof cabin with a 2/12 pitch. We had some trouble finding affordable metal roofing options rating for that flat of a pitch. Standing seam was rated for that pitch but not only was the material more expensive, I was told the installation labor could easily be double.

Exposed fastener metal roofs that I found were only rated down to a 4:12 pitch. At the last minute we found a more expensive exposed fastener metal roof that was rated down to 1:12 and went with it.

It has very wide and deep channels and also has a groove that acts as a capillary break where the panels overlap.

I just posted a lousy picture of it here:

http://www.garagejournal.com/forum/showpost.php?p=6213776&postcount=41

That might be a thread you'll find helpful to poke around in.

At any rate, the metal we used is 24 gauge and was considerably cheaper than even thinner standing seam roofing materials. Install went surprisingly quick so I think the labor savings over standing seam were realistic in our case. That fact that it's 24 gauge and very easy to walk on is a plus.

Since our cabin is only 20' deep I never even priced out the two options pictured in my second reply to this thread. We just used 12" I-joists instead. I doubt that will be an option in Maine with a 32' span.

If you did use free span rafters for even part of the garage you could possibly have your overhead doors go straight up like this:

Just a thought. I would price different options.

 

[Voi]

One other thought on snow.

I've seen large shops with eave overhangs cantilevered well past the overhead doors. Like this:

Should allow snow removal while keeping blade or bucket further away from the building.

 

[MAINEGUY]

One other thought on snow.

I've seen large shops with eave overhangs cantilevered well past the overhead doors. Like this:

http://jarvispolebarns.com/premium/images/eslaman.jpg

Should allow snow removal while keeping blade or bucket further away from the building.

That is another option I have considered. Don't really like the columns
but I'm sure properly constructed gussets would serve the same purpose.

I had not considered the min pitch for standard screw down ribbed metal roofing. Going back to my roof quotes to contact the tentative supplier with that question.

Thanks for the input.

Eric

 

[73RR]

You can have as much overhang as you want, just have the truss designed for the application and get-r-done.
Standing seam metal roofing is good for lower pitch than simple overlapping seams and sno-blocks are easily attached to the standing seam whereas they would penetrate other overlapping panels.

 

[ducatithunder]

I am currently planning on doing the same thing except my roof is going to be 2/12 pitch. I was able to get I-joist beams engineered for the 28x40 garage I want to build. The overall beam length is 32' 6" as I want 3 ft overhangs on the front and 1 ft on the rear. I wanted clear span overheads for car lifts and an attic loft.

Trusses might work better for your roof pitch and you can add a loft to them but you wont get the clear span.

My build is in MD. Ours is about 30psf of load. We get some snow down here but nothing like you would have in Maine.