30' Span and 12' Ceilings -- Is this a problem?

[newgene]

I have hopefully a quick question that you folks may know the answer to. I am in the early stages of building my houses, and I have my plans complete. We are about to pour concrete, and I'm discussing the roof and ceilings with the framer. One concern he brought up is my garage ceiling. The specs are:

Roof: 8 on 12
Width across front gable: 30 ft.
Length of garage from gable to gable: 38 ft.
Main ceiling height: 12 ft. (needed to clear automotive lift).
Ceiling height of the rest of the house: 10 ft.

I was planning for the ceiling to start at 10' at the edges, and go up to 12' where it would level off. The problem the framer is having is with the 30' span. He said he does not know if this will work. Do you think this will work with a normal stick-frame construction? Will I need to have trusses specially made? Any help on this would be greatly appreciated.

Thanks,
Newgene

 

[bobbyd]

Do you have any plans for the attic space? I ask because I have a thirty-two foot wide shop that the roof is framed with pre-manufactured trusses. I did not have them built for a usable attic space other than storage.

A conventionally framed roof thirty foot wide with an 8/12 pitch is going to create a lot of usable space up there. However, it don't think it can be done without a beam running the length of the shop to support the tie (ceiling) joists. This obviously would require columns in the midle of the floor, which I'm guessing isn't preferable. Manufactured I-joists may be able to span that far, not sure. Re-reading your question though, neither conventional framing or the I-joists would be capable of the coffered (10' to 12') transition that you require.

Option 3: pre-manufactured trusses built to include the attic space. If I had it to do over, this is what I would have done. They are more money, but the labor savings to your framer will offset much of the cost of the trusses as they are much easier to put in compared to stick framing a roof that big. They can even be built to accomodate the coffer that you are needing. Just from visualizing, I think this would give you about 7' of head room at the peak in the attic.

 

[mleichtle]

Tail bearing trusses, 30' span is pushing the limit here in WI, but can be done. If you want any storage space, consider lowering the pitch of the ceiling, somewhere around 4 to 6, that would greatly strengthen the truss. Stick framing would most likley cost more.

 

[NHCharger]

Left my 2003 IBC book in the truck. According to my old book for rafters you can span 15'8" using #2 Hem-fir @ 16" O.C.. this is with no finished ceiling and a 40psf live load and 15psf dead load.
If I'm reading this right you want the ceiling joists two feet above the top of the wall. with an 8/12 pitch you would be spanning 24'. Again according to my old book you can span 26' using #2 SPF @ 16" O.C.. This is with a drywall ceiling and NO attic storage.
Since codes vary from state to state you should run all this by your local building inspector.
I would check into a trussed system for the roof. Your going to kick yourself down the road for not having any usable storage up there.

 

[cork]

I had 32 ' trusses made that are 10' height at the walls, they go in approx 3 ' then level off to 12' for a 2' ceiling height. i have very little usable storage above the ceiling but i like the 12' height for a lift.

 

[OldCarGuy]

I found that the pre-manufactured trusses was the best way to go. I have a 12’ ceiling height in a 30x50 garage addition. I ordered attic trusses having a 2x10" bottom cord, 2x8" top cord, 7’ height to collar tie, with 8 12 pitch, spanning 30’. They were designed for light storage at 24” on centers and placed 16” for added rigidity for the 16x50' attic. The flooring was ¾” tongue and groove plywood.

 

[brownbagg]

the 10 foot eaves with 12 at peak will not be high enough for a lift. I know because thats what I did.

 

[logical]

10 foot ceilings in the adjacent house will get you garage ceilings closer to 11.5 ft. Garages are generally a few steps down from the first floor and the ceilings will be at the same elevation. Or you can set the elevation of the house higher and get the garage height. My first floor is about 3.5 feet above garage floor level so I have 12.5 foot garage ceilings next to 9 foot interior (of house) ceilings.

 

[newgene]

10 foot ceilings in the adjacent house will get you garage ceilings closer to 11.5 ft. Garages are generally a few steps down from the first floor and the ceilings will be at the same elevation. Or you can set the elevation of the house higher and get the garage height. My first floor is about 3.5 feet above garage floor level so I have 12.5 foot garage ceilings next to 9 foot interior (of house) ceilings.

Thanks everyone. I'll keep you posted on what we do.

 

[ldog68]

Have you looked at www.socketsystems.com?

 

[newgene]

I had 32 ' trusses made that are 10' height at the walls, they go in approx 3 ' then level off to 12' for a 2' ceiling height. i have very little usable storage above the ceiling but i like the 12' height for a lift.

Cork, that sounds like exactly what I am looking to do. Do you have any details on how they were made, or where you had to order them. I have never ordered a truss or had one made. I remember using the methods of joints and trusses in strengths of materials class, but not much further. I know the theory, but I don't know if you need to build them or have a company supply them.

Also, what exactly would I be asking for? Thanks.

 

[JohnZ]

My attached garage is 58' wide x 44' deep x 12' ceiling, clear span inside, with a 12/12 roof; I didn't want any interior walls or columns, and my architect had a truss outfit design custom trusses 62' long that did the job; it can be done.

 

[Tman]

For the right money ANY truss can be built. 30 feet isnt out of the ordinary.

 

[DaveL.]

My garage has 30' trusses.

 

[Slatewear]

My 30x60 shed has 10 foot walls with a 4/12 pitched roof.

 

[Willy Victor]

My pole building is 30x36 with 32ft. attic trusses. I have usable storage space in the loft of 14x36. The roof is 6/12 pitch with 10ft. side walls. I'm sorry I did'nt get 12ft. side walls. Main joists are 2x8. I'm about 5'9'' and can stand up in the center. The knee wall is about 44ins. Attic trusses are a little more than regular trusses but well worth the money. I don't think width will be a problem as my builder said they regularly make them wider than that. You would be surprised how strong an engineered truss is.

Willy