Putting a loft in a small gambrel roof barn. Want max head room from lower floor and max head room from loft to ceiling. Would like to use 2 X 4 s as ceiling joists to span 12 ft from one gambrel truss to the other just to get the max height but don’t know how to do it without using vertical supports (ties) from the top of the gambrel trusses to the floor. In short how can I span 12 ft with the smallest lumber possible? Thanks in advance for your comments.
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Since you describe this as a loft/storage situation, these are not cieling joists, they are functioning floor joists. The gambrel trusses can be designed with theis joist built in - has to be IMO, anyway, you need a 2x8@ 16" oc for this.
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Install plywood top and bottom making sure none of the joints are continous and are staggered. It makes mini tuss joists withe the widest web possible. Hardest part is lifting the ply over your head and fastening it.
with a 2x4 joist in that kind of span, all that would do is add weight to an already overspanned system. It might add some rigidity, but barely enouigh to cover the added dead laod. still have to deal with live loads
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I wonder if you could cable or all thread to the roofing structure.
Sure, adding to the cost - or - a truss could be done with kneewall to shorten the span perhaps to use a 2x6.
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Thanks - good idea
Thanks, thought of that too, may have to go that route or as someone suggested maybe a kneewall.
best idea yet might try that - thanks
steel
bbbrain,
everybody gets frightened when people use the minimum. You may intend to only put feather pillows there however sombody may decide that is the perfect place to store their weights. What is really needed is to figure out how much weight (load) the area is going to carry and build to that plus a safety margin..
I know that's not the answer you want but let me give you some examples of answers to your problem..
You could use a 2x4 if the load is under 100 pounds total.. That would depend also on the wood used.. for example the typical 2x4 found at home building centers will carry less weight than a douglas fir. and a green ash 2x4 would be able to carry more than a 2x4 of doug fir..
To gain capacity without increasing depth you can either build a box beam or use wider wood (wider not deeper) You could gain some capcity if you use a TGI or if you use alternate woods such as swamp oak. steel will also carry more load for depth than most wood will and you gould get really exotic and use carbon fiber for absolutely the maximum capaicty with the minimum weight.. Believe it or not carbon fiber is within the capability of a do-it-yourselfer.. (and not insanely expensive either)..
hundred pounds total hunh? gotta hire a midget just to send up there to retrieve the feather pillow when It is time for a siesta Mr Roarke?Just the framing will total heavier than a hundred pounds
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What would be the total weight carrying capacity of a carbon fiber 2x4?
frenchy would have to engineer that one - his idea
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no one said if code or building inspectors or lawyers or insurance companies were in on this job
if not , minimum, shucks run 2x2's
but if you want somthing to put wieght in, to be proud of, to sleep at night, listen to the others, not my 2x2's
shoot go into an old trailer trash mobile home, youll find 1x4's for floor joists or "rafters" runnign that span
dont go minimum, dont
when I hear that its like saying code aprroved
its one fraction above failure around here
but then again , some of those "code approved" builders underbid me all the time as they walk across the trampoline floors they build
I've rarely built any place where code is a concern, I just buiold what is right for the job. As he described it, there will be storage space. That means it should not sag or fall in during a lifetime of use. That means he needs 2x8s as far as I know. If he is only storing chicken feathers and doesn't mind some saging, 2x6s maybe. Never a 2x4!
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