11 7/8" I-joists

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Would anyone have any info or links to info regarding cantilevering standard 11 7/8" OSB webbed I-joists. I'm wondering how far I would be able to cantilever a dining nook. Up to 4' would be great and fit in the plans very well. Just wondering if those 12" i-joists can handle a 4' cantilever for the bay window.

oldfrt

Go to this link for specs
PAGES 11-13

http://www.ilevel.com/literature/COM-2000.pdf

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Joe Carola

As far a I know, no I-joists can be cantilevered 4", especially 11-7/8". Either way. you have to follow a installation instructions for whatever brand I-joists you will be using.

If you want to cantilever 4', you can using steel or lvl's with flitch plates in between designed by an Architect or Engineer. Or you can cantilever joists into a double box that acts as a header and then support that with structural brackets back to the house

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Joe Carola

Cache

Thanks OldFrt,

So according to these specs, a 2X10 LSL cantilever from Timberstrand shouldn't have any problem making a 4' extension off my dining room.

oldfrt

I used the 2"x12" for a 4' cantilever in addition to 2 2'x12' lam beams to box around a chimney.My application was for 1 1/2 stories with a lot of glass engineered my the lumber yard,and it hasn't moved in 7 years.
I just crawled under it this past fall to finally insulate it ,so I threw a level on it to check.It can be done but get it approved.

I used mine as an afterthought to give this side of the house a little break in the wall and keep the whole chimney inside for thermal mass. The area between the chimney and the outside wall became the firewood bin.

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REDRC

FWIW, when I used to frame, as long as 2/3 of the joist was inside that was all that had to happen. So for 4' overhang, you would have to have atleast
8' inside secured. Not sure how much has changed, but this is how we did it 8 years ago.

Thanks.

JustaFramer

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JustaFramer

That still works for dimensional lumber. Engineered I joists can only be canted max 1'6 or may be 2 feet.

oldfrt

I should mention that the outside,weight bearing walls were over a cantilevered 2 2"x12" lam beams running back 20' and the TJI's were just carrying the floor.

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RobertCDF

I have seen i joists canted 4' before. There was a beam out there as well because the thing was 4'x10 with another story on top and roof too. The beam was trip 11 7/8" ML following the 3:1 rule. The joists also followed the rule. It can be done but it will need to be stamped I am sure.

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Robert Shaw
Colorado Springs Custom Decks
Colorado Custom Decks
Custom Composite Decks

Cache

Thanks guys. I've considered all the suggestions and talked to a couple people. Looks like the i-joists aren't intended to be left open ended. Very good for spanning larger distances than dimensional lumber at a fraction of the overall thickness and weight, but not very stable if not secured well at both ends.

Looks like I'm gonna go with the 2x10 LSL cants. That should be plently for supporting a dining room. My front foyer is gonna be canted about 2' also, but that shouldn't really be an issue. The only issue there is that it will be supporting two stories and a gable.

Thanks again for all the suggestions.