Joist blocking

Am I missing something here?

Shouldn’t these joists be blocked at the ends if they are not attached to the adjacent joist to prevent them from rotating laterally?

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Up here in Canada - this can be resolved by cross-bridging at third points or near mid-span? Solid blocking could also be used. Unless you see this as a code issue in your area.

Bridging and blockings are usually installed in center spans when the underside is not getting a drywall ceiling.

These joists should be attached to each other with hardware and toe-nailed to the beam below it. With the spacing in your pic, the joists don’t appear to be attached to each other.

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Hey David, what do you think about this framing alteration? New, never lived in 4500’sf, wood frame/stucco structure. Found this added/altered roof framing configuration in one of the two attics. Appears the material was scabbed in after original construction. Don’t know why painted material was used. I first thought maybe prior fire damage during original rough framing.


Harry O travels a lot I guess.

Must have dismanteled old swing sets or barricads to get the lumbe and never pounded a nail in his life.

That is unbelievable.
Hate to see what everything else looks like.

Marcel :slight_smile:

I know this isn’t a code forum, and we all aren’t code enforcement officers, but understanding where the building codes stand, helps me.

2006 IRC R502.7.1 “Bridging” Summery, not a concern unless the joist exceed a nominal 2x12.

Are these bigger than 2 by 12’s?


You’ve got to be shi+ting me. Who the hell (in their right state of mind) is going to consider this rafter install legit?

I can’t believe they went and stole that highway fencing and tried to use it to support a roofing load.

I posted the wrong pic. This pic illustrates the support on a steel beam.

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Will, judging from the quality of the top cuts and the nailing, the carpenter spent the money he was supposed to use to buy lumber on beer. Looks like his soberer buddy cut the bottoms of the overframe jacks.

Yes Jeffrey, the joists should be blocked above the beam with solid blocking.

Anti-rotational devices can be installed in midspan, using either blocks or bridging (X-bracing), but they don’t use midspans in many places any more. That’s because they almost all SQUEAK :freaked-: and they aren’t necessary.

Thanks guys.

I recommended they be blocked and after some time looking at framing guides and the like, I am confident that blocking is needed.

I appreciate the input.

The IRC is a good “guide” for HI’s. However, the provisions of R502.7.1 refer to larger joists (larger than 2x12 which is unusual) that need help keeping them from twisting between the end supports. Any required “bridging” is spaced no more than 8’ apart.

However, it is considered good practice by many to install bridging/blocking between supports even for smaller joists about every 8’ to 10’ to help stiffen up a floor, even though it may not be required by codes.

All joists (not just ones larger than 2x12) need restraint at the ends … which is usually done with a connection to the header/rim joist at the outside walls and solid blocking between the joists over interior walls/beams (per IRC R502.7)

JMO & 2-Nickels … :wink:

That is exactly what I was thinking. Someone pocketed the money.:roll:
Wow! That’s one of the most blatant things I’ve ever seen. Very cocky and they must consider that nobody is going to tag them for it. :neutral:

Dang, boys and girls, thet thar is one of thuh sorriest cuttin’ n’ nalen jobs ah ever seen. My Daddy and Granddaddy, master carpenters both, would roll over in their graves if they saw something like that. They wouldn’t have let me get away with something like that on a chicken roost!

Rob O’Conner said:

According to what we have been instructed as IRC certfied Resdiential Code Inspectors by the ICC, The IRC R 502.7 does NOT require lateral support above girders overwhich floor joists intersect except in Seismic Zones D1 and D2.

The fact they are lapped and nailed to each other is enough to satisfy the lateral restraint at the ends requirement.

Hence, the joists in the original photo require no solid blocking between them unless the house is in an active earthquake zone or other local codes require it.

It is certainly a good idea to block joists over center bearing girders, and I am not arguing against the practice, but no requirement exists to block between floor joists when they terminate over a grider under the IRC except in high probablity earthquake zones… as the ICC explains it.

Thank you. That backs up my original posts.

Sounds like just someones misinterpretation, as that is NOT how the code requirements read, or the intent of that code section. This is a quote of the 2003 IRC …

The converse of the Exception is not true if lapped joist are face nailed together. Just face nailing the joists together does not provide torsional rotation restraint, which is the intent of that IRC section. Imagine a single 2x10 spanning across a 30’ wide house with just support over a center bearing wall (yea, I know they don’t come that way, but just imagine it) … it would twist like a wet noodle near the middle … :shock:

Blocking or solid bracing is indeed required at joist laps over bearing walls or beams (there are some other options … but face nailing laps is not one of them). That is also why IRC R502.7.1 requires solid blocking, diagonal bridging, or bottom brace boards (no other options) at 8’ centers for deeper members. Read the IRC commentary book to confirm those for yourself.

If your still not sure, read Sections 2.3.1 and 3.3.1 of the AFPA “Wood Frame Construction Manual” and commentary (referenced in IRC Chapter 43) which is a little more technical, but should make the lateral restraint requirement crystal clear.

JMO & 2-nickels … :wink:

Sorry to disagree.

But the AFPA Wood Frame Construction Manual does NOT support your claims although it does ‘recommend’ blocking between joist over girders.

The main problem is that the AFPA Wood Frame Construction Manual is NOT ‘Code’. It is simply recognized by the ICC Codes as an approved alternative to the ‘Code’ where the plans submitter agrees to build to its standards. Otherwise, it is NOT “Code” and retains absolutely no authority AS “Code”. And as an ‘engineer’ you should know better.

You should also be aware of R102.4 of the IRC Code which states:

In short: The written Code takes precedent over the referenced standards in Chapter 43 at all times and not vice versa.

Because of this, your claim that *“blocking or solid bracing is indeed required at joist laps over bearing walls or beams” *is simply baseless.

Under the ‘prescriptive’ code this just does not apply…except in D1 and D2 seismic zones.

I have had this discussion many times with ICC instructors and each time have been informed that the intent of the Code has NEVER been to require blocking between lapped joists when they terminate over girders EXCEPT in seismic zones D1 and D2.

I have also called the ICC directly on this question (as a member) and have had their enegineers advise me of the same.

Code Commentaries published by the ICC likewise do not support your position.

That said, it is up to the local *authority having jurisdiction, *the local code enforcement official to ultimately interpret the Code as he sees fit.

Not you.
Not I.
Not anyone else.

Whether or not blocking is deemed ‘required’ by Code over girders where joists lap is left up to the Code Official and no one else BY LAW wherever the ICC codes have been adopted.

So I must continue reject your faulty interpretations for what they remain.

Respectfully submitted,


So…In the long run, it all depends on what jurisdiction you are inspecting in.

Massachusetts code states…

2305.14.2 Bridging: In all floor, attic and roof framing, except as hereafter noted, there shall not be less than one line of bridging for each eight feet (or 2450 mm) of span. The bridging shall consist of not less than one-inch by three-inch lumber, double nailed at each end, or of equivalent metal bracing of equal rigidity.

A line of bridging shall also be required at supports where adequate lateral support is not otherwise provided. Midspan bridging is not required for floor, attic or roof framing in occupancies in Use Groups R-2 and R-3, except where the joist depth exceeds 12 inches nominal or where the minimum uniformly distributed live load exceeds 40 psf (195 kg/m2).

Homebuilt … I didn’t state that the WFCM is a code requirement, but it is a good reference from the IRC (including Chapter 43 & R301.1.1) that I have used myself as a chief building official to interpret the IRC based state code here in NY, and does not give as much latitude.

I guess we will just have to agree to disagree on what constitutes lateral support for joist ends under the IRC … as just face nailing does not provide a continuous member (there are still ends) or provide the intended lateral stability (“lateral support” per IRC 502.7). I do agree the “legal” requirement is up to the AHJ … but wearing that hat I wouldn’t buy face nailing is “lateral support” for a minute.

Now, if the joist bottoms are adequately toe-nailed to a wood beam/wall (often omitted or done wrong … and forget about a steel beam without a top plate) as well as the usual sub-floor joist nailing, in addition to the face nailing of laps … then we could talk about possible “alternates” for lateral stability/support an AHJ might be able to accept.

JMO & 2-nickels … :wink: