Tgi Framing

radarboy

i'm putting a 20' by 26' addition on a 800 sq. ft. home.existing house floor joist run east west.new addition will run 26' the east west way also.my question is any reason not to run the tgi's perpendicular to existing floor joists being its the shorter distance?

knucklehead

No you can run them that way. But you can't span 20 feet.

wallmaxx

http://ilevel.com/literature/TJ-4000.pdf

If it's spec'd out by a floor engineer...you can clear span either way.

And I always called them Tee Jay Eye's...never heard tgi...must be a local thing.

Good luck

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Joe Carola

You can always span 20' with I-joists.

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loneframer

I framed a building in Ocean City that was 22' wide, free span was 21'4". We used TJI 350 series on 12" centers which they were rated for. However 14" 250 series on 16" centers were rated for over 20' when I built my own home. Both of these projects were 10 years ago, span ratings may have changed. Any local lumberyard should have a product guide that will have span tables in them.

Joe Carola

The plans called for them running the 26' way? What size did they spec? Was there a center girder? Ask the Architect why he didn't span them the 20' way.

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Timuhler

Joe,

We have a little garage plan with living space above it and the I-joists were spec'd to run front to back (26') and were 16" deep and no girder. I can only imagine how heavy they would be.

We have a couple of plans we've built where 14" I-joists were spec'd to run 22' and were 12" oc. It was over the garage on the house below

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mikec

Thank God Its Framing

loneframer

Whenever possible shorter spans win the day and I've never heard of a good reason not to. Ever. Saving time on cutting and less time to set fewer joists are not good reasons. Transfering load evenly is key, more joists end bearing, more load evenly transfered. Spread the love I always say.Besides with no center bearing on a 26' span, you will get deflection and bounce, no way around it. 20' span with 2 rows of wood x bridging, stapled when using I joists, no worries.

Joe Carola

I framed a garage with a clear-span of almost 25' with 14" I-joists @ 12" centers. I have a plan hear in front of me for an add-a-level with a clear-span of 28'5" using 18" TJI's @ 12" centers.

In the OP's case sometimes Architects make a mistake and run the joists the longer way for no reason using taller I-joists which are taller than the existing joists therefore lowering the foundation. If he can run them the 20' way it can possibly work out better.

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knucklehead

You can't span 20 feet. What size are we talking about ? You better make sure your addition accomodates for the extra tall joists or when you cut open the existing there might be a little difference in th height of the floor

Timuhler

Joe,

I'm glad to hear you have something to bid on. I've been wondering how you've been doing in this market. How have things been for you?

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knucklehead

I knew what he meant

knucklehead

What is that yellow stuff? Is it Densglas?

radarboy

thanks for all your replies,this is a very nice site

knucklehead

So what are you gonna do?

KentWhitten

That's the second time you have said "you can't"

You can.....and quite easily. Know what you're talking about before you spew off ignorant statements.

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Timuhler

It is the newer housewrap by Fortifiber, called Weather Smart. We used it on a few houses, but went back to Tyvek.

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knucklehead

Does this addition have a foundation to match the height of the existing structure? If so what are the size of the existing joists? If they are 14 inch TJI's then I guess you could make it work. Or if not you could have a step up into your new room.

Joe Carola

That's twice that you said you can't span 20'. That's twice you are wrong. Why do you keep saying you can't span 20' with I-joists. Read my post #10. If the existing joists are 2x8 or 2x10 and the Architect spec's 12" I-joists, all he has to do is lower the foundation. This is done every day. No problems at all spanning 20'.

If the joists are running in the same direction as the existing and the existing joists are smaller, you just bolt a ledger on and keep the taller I-joists flush at the top. Addition foundations don't always match the existing foundations in height when using taller joists.

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