Clear Span Query

[Dan Deckert]

All new construction!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! A 4 wall loft built into a 30x50 shop. (all wood framed utilizing 3 exterior walls) The loft floor is 16x30, with 7'6" ceiling @ the eaves, utilizing the end wall. 30' wide and protruding 16' into the 50' length of the bldg. Loft will have a bathroom (6'x16') with a load bearing wall (2x6) underneath at one end of the 30' span which would leave an open span of 24'.

_____________________________________________ 30' wide | | | | | |

[DAvid Norris]

You said Top of Steel, you're showing your roots

[<moo]

you know i read this 3 times and i am still lost heh

anyway seems you want to span an area with decking?

when you do this you have 2 choices for joists

increase the width of the lumber or decrease the distance between

if you dont want to use a steel I as a support you may want to have a fletch plate which is

1/4" steel bolted between two 2x12s

you can also look into glue laminated beams it looks like really thick osb kinda they are about the shape/size of timbers and are often used as a header over wide garage doors

or wood ibeams next to eachother or wood trusses for beams

so call a truss company fax them a sketch they will tell you what you need

hope that helps remember you can always wrap the Ibeam in wood and center it between the joists and use saddle connectors to hide it

[Bobk207]

Dan-

Took me a while to find what you needed but looks like you really didn&#39;t need much help (just a little reassurance)

This pdf gives you the basics

For a 24&#39; clear span (a residential loft type structure) I would a have guessed a 14" TJI

If you want the floor the feel stiffer (less bounce) bump up to 16" deep or a wider flanged 14"

..........if you get the TJI&#39;s from a knowledgeable supplier they will be able to evaluate your situation.

Where is this being built? You might consider checking with the local building dept or get an engineer to take a look at your design

cheers Bob

[Dan Deckert]

TOS---Top of Slab.....??? LOL Yer probably right on the mark tho..............

Dan

[Dan Deckert]

gonna look @ these

I just don&#39;t know what&#39;s being used or is available in wood for clear spans. Engineered beams are acceptable for the owner, he just needs the headroom.

Good thought for me to go after

Built in the county with basically no requirements but an electrical/water/septic inspection. All dwgs. will go before an engineer for stamp/approval. It may be a hick county but we&#39;re going past that point for assurance/insurance/longevity. We&#39;re just trying to get everything in place for a plan review & approval by an engineer prior to submittals. The owner will overbuild rather then underbuild.

Dan

[HerHusband]

Dan,

What kind of loads are you expecting to put in the loft?

For sleeping areas or light storage, you could use regular 2x12&#39;s at 12" OC to freespan 24&#39; (See the span calculator below)

As a reference, I used 2x12&#39;s at 16"OC to span our 24&#39; wide garage. It is way too bouncy for a living area, but works fine for storage or walking around. I wouldn&#39;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&#39;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 Deckert]

Anthony, my only concern at this juncture is the 24&#39; 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 &#39;480 sq. ft. loft&#39; 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&#39;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&#39;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

Aint&#39; gonna happen..................at least according to the owner................yet.............:-)

Dan

[Bobk207]

Dan-

Your gut is well informed.........2x12&#39;s over 24&#39; is too lightly framed for your application (unless of course you don&#39;t mind living / walking on sprngs)

Anthony&#39;s example of 2x12 @ 16" oc over 24&#39; for light storage / attic in a garage is ok but even at 12" spacing 2x12&#39;s over 24&#39; are too light for a living space

It all depends on your desires downstream......

I&#39;ve seen 22&#39; 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&#39;s aren&#39;t cheap but you&#39;ll get a much better result...esp if the system gets much use downstream

I&#39;d go with TJI&#39;s at 16" oc & a decent floor deck 5/8 min (3/4 better) T&G

cheers Bob