Floor joist cross bracing

Thanks Robert, now I just hope some will believe me when I tell them what you are telling us. :mrgreen:

Good luck with that … :mrgreen:

I had a tough time, and you guys know me. Maybe the NAHB/HUD design guide quote that references actual testing of joists with bridging … :wink:


In 35 years of building (as a carpenter- later as a general contractor) I never heard of any floor system failing because it lacked anti-rotational devices like the bridging or midspan blocks discussed here. I can say from experience that one or the other device should definitely be installed if you want a floor to squeak. Forget glue… it won’t help.

I agree … there is a potential for floor squeaks anywhere there is wood to wood contact without both glue and screws.

The newer adhesives are a lot better … local builders all swear by them. Combine that with screws and you have a really solid squeak-free install. I see it done wrong sometimes where the builder puts down adhesive on too many joists at once, and it starts to set up … which can actually increase the likelihood of floor squeaks.

JMO & 2-Nickels … :wink:

Robert, here is one from APA, are they wrong too?:slight_smile:

Squeaks and Bridging by APA

And yet another here. :slight_smile:

and here;

American Forest and Paper Products

Not sure what you are referring to as that link to APA TN-C468N talks about bridging possibly causing squeaks, particularly if some load is transfered to the bridging (yes, a negligible amount can be transfered) and it’s not securely nailed.

Here is a current APA Builders Tips guide on preventing floor squeaks … http://www.apa-europe.org/Languages/English/PDF/Q300L.pdf. Installing bridging isn’t included, as it can actually lead to squeaks.

Then ya have a home movie clip of Bubba building his own house where he “got my two by tens” with some of dem dare simpson bridging … and of course ya have to “tack it with some nails” in order to get a “pretty tight floor system”. Here is a clip of that same guy calculating how “tight” it’s gonna be … http://www.youtube.com/watch?v=oldOh_R9nws&feature=mfu_in_order&list=UL … OMG I must be completely wrong … :stuck_out_tongue:

What is the quote and page from the AFPA details guide are you referring to? I only see a reference to bridging on Page 7, which talks about installing that if a joist depth-thickness ratio exceeds 6.

Robert, it just seems that every where I look, Bridging is shown everywhere.
Is someone changing the history books showing that bridging is no longer a building standard or a requirement?
That is all I am trying to point out.
If I ever go out and tell a builder that he is wasting his time on installing bridging, I know he will look at me and ask if I came from another planet. :):wink:

If a builder wants to install them thats fine. It cant hurt, as long as it’s installed correctly so that it doesn’t create floor squeaks.

But the bottom line is missing bridging is not even an issue worth mentioning on a home inspection.

Well, to be honest, it never worried me either, unless I saw a problem or cause that would have required it. And if it did, it was usually undersized, overspanned.
Just trying to find a balance in the requirements. I test it one of these days and go from there. :mrgreen:

Bridging 2006 IRC 502.7.1 - required when joists EXCEED a nominal 2x12 size.
That would be anything more than a 2x12 needs bridging, but a 2x12 does not.
I have never seen any 2x14 joists, but when I do, they will require bridging.

Its is not common practice here to do bridging.

Now, section 502.7 (2006 IRC) DOES require “Lateral restraint at supports” which is different. This section offers some ways to achieve this, and then the last sentence “or shall be otherwise provided with lateral support to prevent rotation” (THIS IS AT SUPPORTS)

How I interpret this is:

Bridging not required.

If I cannot prove the sub floor is attached in accordance with the “or shall be otherwise” sentence) then some lateral support “at supports” is required.

Bridging does not strengthen or stiffen a floor.
We do block between floor joists here to support a line load from a wall above.

If there is some way the requirements from 502.7 are met, and the joists are not larger than a 2x12- 502.7.1 is not a requirement. If you are using 502.7.1 to satisfy 502.7, then I would interpret this to mean it would have to be at the ends.

The code is the minimum, but it is also the standard.
Just because something is a good idea, doesn’t make it a requirement.

This only my interpretation and understanding, I may very well be wrong-and I am always learning.

Not to open a can of worms, but there is another can in the ceiling section when discussing strong backs and rat runs.

I do reccommend that the botton gets nail aswell, as we all get older we all need more reinforcement.

I’d agree with Robert IF the joists are smaller than 2x12.

What kicks me is the number of times I’ve seen them put in on 2x6, 2x8, 2x10 AND even 2x12 where they’re nailed at the top but hanging loose at the bottom.

WHY bother putting them in if you’re NOT going to finish the job. Just skip that step for crying out loud.

That’s what I essentially see all the time. I wondered the same, why bother? WHich is why I asked. Good info for all.

Yup, that says it all on that link. Floor joist cross bracing - Specific Inspection Topics / Structural Inspections - InterNACHI®️ Forum

The bridging prevents rotation of the joist and helps distribute any concentrated floor loads to adjacent joists. While it may not have been a problem for 20 years, if the new owner puts a baby grand piano on that floor a problem could occur. So I agree with others you should mention the defect and move on.

I am not debating the need for cross bracing. But I find it interesting that I have never seen cross bracing with engineered I-Joists.

Bridging is sometimes required in floors or roofs when solid-sawn lumber joists are used. This addition provides lateral support to twisted joists to help maintain a vertical orientation. It also facilitates load sharing. Load sharing can be important because of the large variation in material properties found between joists within any solid-sawn lumber grade-group.

Trus Joist® TJI® joists are made with no observable twist and have minimal material variation between joists within any joist series/depth. Consequently, they do not see any significant benefit from bridging. Our code report (ICC ESR-1153) specifically states that bridging is not required for floor and roof TJI joist applications . Weyerhaeuser has found that the addition of bridging does little to improve floor performance and may create squeaks . It is the policy of Weyerhaeuser to recommend against installation of bridging unless an unusual condition exists that would be improved by this addition.

Mine always had the same, Marcel. I liked a sturdy great floor system, too.

And I am a licensed builder since 1973.

The key word here is engineered and what Marcel quoted:

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I agree. That explanation makes perfect sense to me. Good stuff. Thanks.

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