Floor joist blocking straps...should they be used?

Saw this on an inspection today. Didn’t see any twisting. Thoughts? Should the straps be utilized? (What’s the correct terminology to refer to these straps?)

P.S. The floor above is wood, if that makes any difference.

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Yes, the bridging is 1/2 installed.

Why is it required, Larry? Is blocking or bridging always required? If the straps hadn’t been there at all, would that be a defect? (I probably wouldn’t say anything if they were absent.)

They’re used to make the floor more rigid. Was there a tile floor above?

I would just recommend completing the installation since it was started.

There was tile and T&G wood. Correct.

I just feel bad for saying it should be completed, when if it had been absent I wouldn’t have said anything. Looking for a reason that it is necessary.

It may save the tile floor from cracking and keep the china from rattling.

Plus, like I said before, it is there and only 1/2 installed.

A recommendation to finish the job would be of no consequence.


I ran into this same deal a handfull of times. Why there not always fastened at the bottoms, I don’t know. But anyway, here’s what I’ve come up with:

Crawlspace: floor joist bridging
The metal floor joist “X” floor joist ties or bridging brackets were not fastened at the bottom and/or not properly attached in one or more areas. Floor joist bridging is critical to the structural strength of a floor. Proper bridging distributes the load on the floor to other joists and over time prevents floors from sagging and squeaking do to floor joists twisting and warping. Recommend repair and/or reattaching.


Because they forgot to finish it after the insulation was installed . I write it up . If it isn’t present i mention it there is several ways of installing it and it does stop the twisting and squeaks. I lot of builders will say it is not necessary but of course where are they when the problem occurs .

Some municipalities in my local do not require bridging. Alot of the builders do not complete the installation because they have had bad response from the home owner. The home owners have been complaining of squeaking from the bridging rubbing against itself. I have not experienced that problem personally. That is the info I’ve gotten from other builders.

Most framers will bridge when spans exceed 12 ft,…usually common with 14 - 16 ft spans and that being at the midspan point…HOWEVER it is not required unless joist exceed 2x12 and then you can either bridge by cross bridging (also called diagonal bridging), solid bridging (shouldn’t be offset) or a continuous 1x3 strip nailed along the bottom of the joist perpendicularly.

Bridging does indeed help distribute loads as well as reduce squeeks.

When one sees it incomplete than it is often because the framer inserted same from the top just before installing the floor sheathing but failed to jump down into the crawlspace to finish the job.

In this particular case it appears that the builder / framer simply picked up the wrong metal cross bridging…those appear to be for joist 24 inches on center…not 16 inches.



Good eye. I agree. wrong bridging

Whoops! Report has already gone out!

Good eye Jeff.


While bridging is good to have…and those spans appear rather long, probably 2x10x14 joists, based upon building code you are fine…its not something that is going to adversely effect the habitability of the home. (which is your escape if its ever brought up).

Worse case is to simply go back and install a 1x4 (1x3 are obviously uncommon) along the bottom and be done with it.



What Jeff said. Bridging is an anti-rotation device, but mainly it encourages squeaking, which is even worse when they require midspan blocks. Wood cross bracing can squeak too.

If bridging was part of original design it should be installed. It is a lateral bracing of the joist bottom chord. The joist has more load capacity if it is laterally braced on the bottom edge. Just because it is not twisting today does not guarantee it won’t later. And remember the floor joists were design based on a 40 PSF floor live load (if it is a first floor). What if a pool table or something large was placed on the floor. You never know. Bottom line if it was there and intended to be installed why not just state for them to finish it? And yes, if it was absent to start with how would you know it belonged there? You don’t, since you did not design it. There are a lot of redundancies in structural design so will it be a problem? Maybe never…I would have written it up. Seems like a waiving red flag.


I would have written it as well however unless the HI is privy to the blueprints then one can not say as to whether it was part of the original design. Some builders will install bridging (of various types) regardless whether its on the prints or not. As to twisting…considering the joist are (or should) be tied to the band joists and blocked over girders (we block over girders) then they are not going to twist, especially if they are glued and nailed at the top.

Also, while bridging does help reduce deflection to a small extent, one can not assume they can account for heavier loads…that is what piers are for.


Most the squeaks I had to fix were the result of the subfloor and / or wall bottom plates not being properly nailed (seated); don’t ever remember coming across where bridging was part of the problem although I suppose its possible.
I rarely see metal bridging used anymore… at least not here in the south as much. It was more popular during the 70’s and 80’s.

I subscribe to the belief that all homes are going to have some squeaks here and there… especially considering the number of nails used to frame a home; yet many can be resolved with screws, glue and shims.