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Posted by Bobk207 on January 5, 2007, 1:31 pm
Dan Deckert wrote:
> Anthony, my only concern at this juncture is the 24' freespan. That span
> will be supporting a floor to roof wall with all the stuff upstairs. In this
> case, a kitchen w/counters/dishwasher/fridge etc. and cupboards plus an
> armoire. This '480 sq. ft. loft' as it were, will be used to provide full
> living, albeit cramped & small, quarters for weekend visits and during
> construction of the house. Afterwards, it's a crapshoot, although I suspect
> the bed and armoire will be gone so it can be used for a
> get-away-from-the-wife room. When my dial-up connection gets back to speed,
> I'll run your spancalc to see what I can glean from them.
>
> As for > Of course, adding a single post and beam in the middle of that span
> would
> > greatly reduce the size of the joists.
> Aint' gonna happen..................at least according to the
> owner................yet.............:-)
>
> Dan
>
>
> > What kind of loads are you expecting to put in the loft?
> >
> > For sleeping areas or light storage, you could use regular 2x12's at 12"
> OC
> > to freespan 24' (See the span calculator below)
> >
> > http://www.cwc.ca/design/tools/calcs/SpanCalc_2002/
> >
> > As a reference, I used 2x12's at 16"OC to span our 24' wide garage. It is
> > way too bouncy for a living area, but works fine for storage or walking
> > around. I wouldn't want to store truck engines or a library up in our
> > attic, but for light storage (Christmas decorations, suitcases, camping
> > supplies, plastic pipe, etc.) it has worked well for us.
> >
> > Reducing the joist spacing to 12" OC would stiffen it up further. If
> lumber
> > costs are not an issue, using 2x12's might have advantages.
> >
> > Otherwise, you could probably use 14" or 16" wood I-joists.
> >
> > Of course, adding a single post and beam in the middle of that span would
> > greatly reduce the size of the joists.
> >
> > Anthony
Dan-
Your gut is well informed.........2x12's over 24' is too lightly
framed for your application (unless of course you don't mind living /
walking on sprngs)
Anthony's example of 2x12 @ 16" oc over 24' for light storage / attic
in a garage is ok but even at 12" spacing 2x12's over 24' are too light
for a living space
It all depends on your desires downstream......
I've seen 22' spans (kitchen / living area) over a garage with 12" deep
floor trusses. The designer went 12" instead of 14" to shave floor
height on a multistory condo to keep within the overall height limit.
The owners hated the bouncy feeling & the retrofit was a real
pain...those extra 2" would have made a big difference.
Yeah, the TJI's aren't cheap but you'll get a much better result...esp
if the system gets much use downstream
I'd go with TJI's at 16" oc & a decent floor deck 5/8 min (3/4 better)
T&G
cheers
Bob
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