TJI SPAN Question

msc5195

I have a homeowner wanting me to build him a 24' x 28' garage with a 11' x 20' bonus room above. The garage will be standard 2x4 construction with insulation, sheetrock, vinyl siding and have a 10/12 shingle roof. He has plans that were drawn by a local draftsman. His plans show using 16" TJI's spanning 24' as floor joist as with NO center LVL or Beam. I questioned the lack of a center Beam and he tells me that the draftsman and the truss company providing the TJI's assured him that they were properly rated for that span and that no center support was needed. I have only been building for a few years and haven't used TJI's that much so I am still a littele green with them. His lowest bid thus far is 85.00 a square foot so I feel like I can get the Job for 75.00-80.00 per sq ft but I am a little reserved about taking the job.

Looking at the GP website I see that the TJI's are in fact rated for the span but I still wonder about the need of a center LVL.

Not saying that it is right or wrong would anyone accept this job based on his plans?

BuiltByMAC

Is the draftsman an engineer? Do the plans have an engineer's certified stamp on them?

Mac

WarnerConstInc.

Goodness, some of these things make my head hurt.

Deicide1

The TJIs that I'm used to using you would need to use 16'' ones and you would need to be 12'' on center. Even with that, they still deflect like crazy. I would imagine the floor would be a bit bouncy.


Go with an LVL in the middle supported on both walls and use a steel post in the center.

D.Foster

Your own doubts aside,.. if the manufactures specs are ok and you install all the proper squash blocks or web stiffners, bridging etc. i don't see a problem. There wont be any point loads on the floor right? There are diff grades of tji as well, 110- 560 series. we just did a floor system with 18" 560 series. Just dont walk on them unless you brace them with some 1x!!

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ScipioAfricanus

At that span the garage is just at the limits for conventional construction which would require 2x12s at 12" O.C. D.F. or Larch considering a dead load around 10 lbs. and a live load at 30 lbs.

Now I don't know how the rest of the garage is designed which might impact the floor other wise so I am not giving you any kind of advice on weather or not to proceed but i would do it conventional const.

You will still get some bounce with the 12s but I think not too bad.

What concerns me is only charging 85.00 per sq. ft. WTF? How do you make money at that price? Is this in Mexico? Here in So. Cal 125.00 would be more in line even for a garage, not including drafting and engineering.

Andy.

SDC

There really is no such thing as 12" oc ones or 16" oc ones. There are different series ones that are rated for spans, loads and deflection.
A 1 1/8" x 9 1/2 will not support as much as a 1 1/2" x 16" speaks for itself.

Most REAL lumber yards will be able to help size them for you (software supplied by the manufacture)

As for the sq ft pricing...how do you price anything by the sq ft?
Example
10x10 room has 100 sq ft
40 ln ft of wall
maybe 40 studs

2x50 room has 100 sq ft
104 ln ft of wall
maybe 80 studs

D.Foster

That may be useful if he was using conventional lumber,he is using tji's.

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Deicide1

Uh, I'm talking dimensions... This is the brand we use, and right in the table it will show a 16'' TJI set at 12'' on center...


http://www.kentinternational.ca/broc...System/TJI.pdf

msc5195

The drawings were done as side work by a Draftsman who works for an architect firm. He had drawing before I ever met him.

I suggested a 16" LVL in the middle but he doesnt want a center post. Not sure what size LVL it would take to elimanate the center post.

This is in south Georgia. The going rate for a basic spec house in this area is 65.00-90.00 sq ft

672 sq ft Garage with an unfinished bonus room
672 x 75.00= $57,120.00. This is a nice pay day. We are hungry down south and the jobs are few and far between.

Mike(VA)

Why not just truss it? The out to out is only 24'. Truss company could spec those out easily and you wouldn't have to worry about 'redesigning' a job you are only being paid to build. I would at least do a cost comparison between truuses and stick building. Less labor, no hangers, quicker to weather in. Not a sermon, just a thought.

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bighammer

have your local lumber or truss company work up an attic style truss. They can design the trusses with a 14-16' opening in the center of the truss for this "bonus room" the pitch will be step, but it would be my prefered choice. I would feel more comfortable with that, they have computer programs and went to school for that, it is beyond me.

I would also always go with a deeper beam if my head room allows. Keep in mind that there is a ton more in floor design than reading tables. The 16" I's may work in the situation, but would feel like you were walking on a trampoline. The deflection has to be high.

If the truss idea fails, consider running a flush mount lvl down the center of the garage and hanger the I's from that.

Trusses might be less labor....chaaaaa ching.........

Solrac

Im actually finishing up a Master bedroom above an existing 24'x24' garage below. The architect sized up 14" TJI's 16" O.C. from end to end with no beam in between. We did install bridging in the center however. Deflection is ok, nothing above normal. Roof loads from above are being transferred to the existing walls and foundation below. No pressure in the center besides standard live loads.

I would check the manufacturer span tables for your project. The sizing depends on the TJI series number, and they also give you calculations for what the expected deflection will be.

bwalley

Trusses typically work better for most cases, especially when you figure all the extra labor and material to use TGI's and then there is the issue of running your Mechanical systems.

Remember span charts will list the maximum span and load allowed, it doesn't always mean that is the correct use.

msc5195

No matter what agreement we sign My name and rep will be on the line if the HO isnt satisfied with the end results. I had rather do it right the first time.

Trusses are less Labor but will require a boom truck rental @ 110.00 per hr with a 6hr minimum

Joe Carola

I just picked up a set approved plans from an Architect today for an Add-a-Level w/18" TJI 360 @16" O.C. 28'5" span and the width of the room is 17'. Room above is the Master bedroom with WIC, Bath with Stall shower and Jacuzzi and half of the laundry room sitting on the joists. Tallest I-joists I've used so far. Twice I framed a garage with a room above with a 24' span using 14" I-joists @ 12" O.C. Floor wasn't bouncy. They were not TJI's and they weren't bouncy.

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Joe Carola

SDC

Are you trying to tell me I cannot use a 16" TJI at 16 oc?
I did not say a 16" TJI could not be used 12"oc, just there is no such thing a 12" oc TJI's and 16"oc TJI's
What if my span was 12' or only 8'?

What I was saying is...

There really is no such thing as 12" oc ones or 16" oc ones. There are different series ones that are rated for spans, loads and deflection.
A 1 1/8" x 9 1/2 will not support as much as a 1 1/2" x 16" speaks for itself.

Read what I said, not what you think I said

D.Foster

Some engineers will call for odd spacing. We are building a house where they called for 18" 560 series @ 12" O.C. because of a custom organ being installed over the floor there. But you are right, they are not specd on spacing, but series.

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Do what you would do, as if i won't Do anything after you Did It!

SDC

Talk about odd spacing, back in the 80's we did condos where the floor trusses were 19and a touch over 3/16"
BTW that's what the little diamond is for, on your tapes, if some of you did not know.
I also have some specs on my desk now that the "designer" wants floor trusses 11 7/8" x 24' TJI 560's @ 8" oc. So... with 3 1/2" wide top and bottom cords it does not leave much room for nailing (hammer or gun)

precisionbuild

That's wild! I'd like to hear more of the details. You would almost have to use a palm nailer.