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tonfan 11-17-2007 11:29 PM

Question regarding removing ceiling joists...
Hi everyone,
I am building a 10x12 storage shed/workshop with a 6/12 pitch gable roof.The roof plan calls for a 2x8" ridge board with 2x6" rafters on 16" centers.The ceiling joists are also 2x6" on 16" centers....I am now thinking of insulating and rocking the 2X6" rafters underside to give the shed a more open look....My question: Can I increase the size of the ceiling joists to 2x8" or higher;but use fewer joists ? Let's say on 24" or better yet,30" centers?.. By the way :The roof sheathing will be 1/2 ply with composite shingles and I am not in a snow area...Any ideas would be much appreciated....I have a pretty fair knowledge of construction;but the engineering side of things throws me a bit....Many thanks!

kemerick 11-18-2007 01:17 AM

With 2x6 joists, 24" centers will be more than fine...

UBoiler 11-18-2007 01:43 AM

Keeping in mind that 16"on center rafters will rest on a top plate and directly under each rafter will be a wall stud also at 16'OC, if you change your engineering design for rafter spacing you will likely need to 'beef up' your top plate design. Leaving the design alone other than increasiing the dimensional sizes shouldn't be prohibitively expensive. I'd run the numbers.

I know in snow belt we have free air vent space 1/2" or better from the soffit vents to the ridge vents between our insulation and our roof plywood sheeting to protect from condensation. This space also lets the insulation work against the outside temperature and not sun-baked hot roof. Be sure to know the proper insulating technique for your region and climate to get the maximum benefit of your design and insulation. Good luck. Cliff

tonfan 11-18-2007 02:31 PM

Ceiling joist spacing in 10x12 storage shed..
Thanks for the replies...I am not altering the rafter spacing,only the ceiling joist spacing...I will probably go ahead and space the 2X6 ceiling joists at 24 o.c. over the 12' length of shed;instead of the 16" O.C. shown on the plans...

Kingfisher 11-18-2007 06:12 PM

The ceiling joist are only serving as tension members, forming the bottom cord of the roof "truss", you could replace them with a 1/4" cable in theory. If you are using a double top plate you only need 2 2x6 joist placed in 4' from each gable end or 4' on center:thumbsup: , but makes sure that you secure them will because they well be keeping the roof from pushing the walls out:eek: .

tonfan 11-18-2007 06:35 PM

hey thank you Kingfisher and everyone for the replies.I will maybe put in 3 joists for good measure....Tonfan

joasis 11-18-2007 07:28 PM

And you are saving how many joists? I cannot tell you how long it has been since I saw a house with a roof framed on 16" centers, or a ceiling for that matter. And with a 10 foot span, why 2X6's? For that matter, why 16 for the studs? If you sheeted the interior walls with osb, and not sheetrock, 24's would work all over.

Kingfisher 11-18-2007 08:06 PM

I don't think he is changing anything but the ceiling joist because he is putting the drywall onto the bottom of the roof rafters for a open cathedrel ceiling. Everthing else is still 16" OC right:huh: ? I with Joasis on the 16" centers no real $ savings for the wood you are cutting out by going to 24"

send_it_all 11-18-2007 11:01 PM

If the design would allow it, I would eliminate the joists altogether and use collar ties on every other rafter.

tonfan 11-18-2007 11:56 PM

Thanks everyone for the further input...Yeah,I agree the stock design for this storage shed may be a little overkill-especially with the 2X6 rafters(and ceiling joists) on 16" centers...I do know we are going for the opened-up cathedral look..I also have played with the idea of collar ties and omitting the least now I have a good batch of educated suggestions from you all -so I can tweak this thing. It is much appreciated....Tonfan

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