floor joists over beams.

[JStructsteel]

I inspected a home this weekend that has floor joists supported by wide flange beams. They are offset and lapped about 1'-0" on each other. They are starting to roll over, and was wondering if the normal detail should have been to put some blocking in at the supports. Also, at the end it doesnt look like there was any blocking where they are supported on the walls. there is some x blocking at the mid-span.

Do you think to remedy this to add some blocking? this will help stop them rolling, and stiffen up at the support.

Thanks
Jim

 

[kslee1000]

Are the joists supported by their's top chord, or bottom chord? Are joist twisted or bent in a bow shape? deflection?Is there bridging at the bottom chord? When you say "blocking", does that mean bracing?

 

[msquared48]

Since they are offset and lapped, they are bearing on top of the steel beam. Yes, install the blocking that should have been placed in the beginning.

There should be blocking or a rim joist to nail the floor joists to at the exterior wall.

Mike McCann
MMC Engineering

 

[JStructsteel]

Kslee, they are wood joists, bottom bearing. Its a bad detail in my mind.

MSquared, thanks for your response too, glad someone is hanging out on sunday nite when I try and do some work.

 

[kslee1000]

I think Mike got it right. I was only making some noise on the raining, boring Sunday afternoon.

 

[mark1234]

Floor joists bottom bearing on an interior beam is normal construction w/out blocking if not required from load above.

Racking of the joists may suggest a bigger problem... No perimeter nailing into exterior rim board would certainly be one but to be honest have never seen the rim board not installed.

If they are rolling over it seems to me that the floor has actually shifted?? Something is going on but no blocking at interior bearing should not cause this, IMO... look at exterior connections in more detail.

And yes... blocking at this point would help.

MDJ

http://www.windspeedbyzip.com

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[JStructsteel]

There was some other issues too, a built up beam was spanning column to column, but also had one edge supported on another beam about 1'6 from one end. this has caused the beam to roll a bit, I think thats the start of the issues.

 

[COEngineeer]

Yes.. you need blocking. If you get installation manual for I-Joists, they always put blockings. You need to do the same if you use 2x.

Never, but never question engineer's judgement

 

[darkness0621]

If you have joist that break on a bearing point, they need to be blocked, regardless if there are loads coming down or not. That is the reason they rolled over. I work with i-joist daily. If the ends were secured by rim board, then blocking was needed at the ends too.

 

[BAretired]

Blocking is a good idea, but you don't necessarily have to provide it in every joist space. If you do not require "squash blocks" then it may be sufficient to block every third joist space.

BA

 

[ctcray]

"IRC 2006 R502.7 Lateral restraint at supports.
Joists shall be supported laterally at the ends by full-depth solid blocking not less than 2 inches nominal in thickness; or by attachment to a full-depth header, band or rim joist, or to an adjoining stud or shall be otherwise provided with lateral support to prevent rotation."

There should be blocking at some point along the beam if not every bay. The fact that the joists have rolled already sounds like the bigger problem.