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-   -   Roof without ceiling joists? (http://www.diychatroom.com/f19/roof-without-ceiling-joists-12712/)

bluegrasslover 10-25-2007 08:04 PM

Roof without ceiling joists?
 
Hi,
I'm a DIYer that's making plans to build a wood working shed in my backyard. I do woodworking as a hobby but I've never done any construction such as this. The workshop is going to be 16x24. I want it to be very open and have enough room vertically for moving wood around etc. I'm planning on building the roof using ridge board construction. My question is can I build the roof in such a way that I would not have to have ceiling joists? I would really like the vertical space without having really high side walls.
The roof will have an 8/12 slope built with 2x6 24" o.c. and a 2x8 ridge board. Using collar beams would be fine since they would still give me lots of vertical space. The side walls are most likely going to be 9'.
I appreciate your help!
Thanks,
Greg

concretemasonry 10-25-2007 09:35 PM

As long as it is designed to be stable and the roof does not push out the side walls, it will work. If the collar ties are designed properly, they will prevent the excessive load to the walls. - You may have more money in joist matrial than you would have in trusses.

moneymgmt 10-26-2007 08:22 AM

16'x24' is one heck of a "shed"!! I don't know about where you live but I can't see 24" o.c. w/o cross braces passing code on a building that size in my neighborhood. If you are disregarding code, I would at least run some type of cross brace higher up to pull some of the weight down opposed to out.

truckerwoman48 10-26-2007 10:18 AM

what are other folks doing?
 
It seems to me that everyone from the McMansion builders to the remodelers are trying to grab all that vertical space to make it all seem bigger. I have seen some pretty ordinary homes getting opened all the way to the rafters. How are THEY doing it? Without a flying buttress, only found at a Gothic cathedral or the phenomenally ugly stadium in Dallas, there has to be a way of transferring the roof weight to the ground without causing splaying of the walls. New materials notwithstanding, I would still be uncomfortable with no trusses at all. How about placing them farther up the triangle, a compromise that will gain height without eliminating support. Do you guys who know more than I do have any thoughts on that? I think, on reading along again, that's what moneymgmt just said. Duh, well call this a corroborating view.

skymaster 10-26-2007 10:36 AM

build it as a gambrel roof. cross ties and that should get ya more room

Longtooth 10-26-2007 10:46 AM

8/12 is a heck of a pitch. If you go with a stronger ridge beam (4x12) and set it on posts at each end, you might be ok. Collar ties as recommended above would still be a good idea.

bluegrasslover 10-26-2007 12:21 PM

Gambrel is out because it has to at least resemble my house (home owner covenants crap). Yea, big "Shed" but ok sized workshop. Yea, collar ties (beams or whatever) is what I was thinking on every rafter, maybe halfway down. I guess I'll just have to find a local structural engineer and fork out some bucks to know for sure. I want the vertical space but I also don't want the roof on my head some day down the road! I appreciate everyone's advice.

Thanks,
Greg

PKHI 10-26-2007 08:40 PM

Quote:

Originally Posted by truckerwoman48 (Post 69979)
It seems to me that everyone from the McMansion builders to the remodelers are trying to grab all that vertical space to make it all seem bigger. I have seen some pretty ordinary homes getting opened all the way to the rafters. How are THEY doing it?

Its called a scissor truss

truckerwoman48 10-26-2007 09:24 PM

Quote:

Originally Posted by PKHI (Post 70084)
Its called a scissor truss

Ooooph! SCISSOR TRUSS! I'm going to look into that. Thanks

Joe Carola 10-27-2007 07:52 AM

Quote:

Originally Posted by bluegrasslover (Post 69925)
The workshop is going to be 16x24. I want it to be very open and have enough room vertically for moving wood around etc. I'm planning on building the roof using ridge board construction. My question is can I build the roof in such a way that I would not have to have ceiling joists? I would really like the vertical space without having really high side walls.
The roof will have an 8/12 slope built with 2x6 24" o.c. and a 2x8 ridge board. Using collar beams would be fine since they would still give me lots of vertical space. The side walls are most likely going to be 9'.
I appreciate your help!
Thanks,
Greg


Greg,

Which direction are the rafters running, is the span the 16' way or the 24'?

Also, do you have a maximum height to the top of the rafters from grade level? We can't be any higher than 15' here in NJ. way?

Either way you run the rafters, you can put a structural ridge in without any collar ties. If you run the ridge the 24' way, you obviously have to put a bigger structural ridge.

If you're running the rafters with the 16' span and the garage door is in the 16' wall and you go with a structural beam, your garage header will have to be designed to handle the beam. With your 9' walls and an 8/12 pitch using 2x6 rafters, your height will be 14'8-1/4".

bluegrasslover 10-28-2007 10:27 AM

Yes. The door is on the 16' side and the beam will run the 24' length. I'm in the Raleigh, NC area and I'm pretty sure the rule is that a secondary structure can't be taller than the main structure. My house is 3 stories.

Greg

Joe Carola 10-28-2007 05:46 PM

Quote:

Originally Posted by bluegrasslover (Post 70295)
Yes. The door is on the 16' side and the beam will run the 24' length. I'm in the Raleigh, NC area and I'm pretty sure the rule is that a secondary structure can't be taller than the main structure. My house is 3 stories.

Greg

Greg,

That rule doesn't sound right because that means that you can frame the garage three stories? Check first with the building department. I know I'm form NJ and things are different all around, and a detached garage can't be any taller than 15' here. Just don't want to see you get in trouble.

If you don't want any structural collar ties, then get a 24' beam specked form an Architect or Engineer, and also a header specked above the garage door to support it. If not you will have to have structural collar ties designed at a specific height so that you don't need a structural ridge.


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