What is the difference between web stiffeners and squash blocks? When should you use each?
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Greetings,
In my neck of the woods a web stiffener is used on engineered wood "I" beams, (TJI etc) as required by mfg. Squash blocks or crush blocks are nailed to side of the bottom chord of a truss where it fastens to the top plate.
The 'Framers Pocket Guide' that comes with each batch of TJI's is really the source document that will help you with this. But in case you haven't yet gotten your batch.....
A 'squash block' is designed to transfer the downward load of a weight bearing wall above the TJI, to the wall below. Seems the wooden I-Beams are not designed for compression, but for tension. just make sure the squash block sits proud of the top of the TJI by 1/16" or so....my inspector laid a straight 2X4 across the top of all of them then eye-balled to make sure all tops were above the plane of the top of the TJI's.
Web stiffeners are simply used in the web of a TJI as it goes over a wall below but where there is not a weight bearing wall above.
You can download the pocket guide as a .pdf file at
http://www.trusjoist.com/PDFFiles/2030.pdf
BruceM
So all ends of I-joist need squask blocks? Do even gable walls where there is no roof load?
No...only under weight bearing or sheer walls.
Take a look at the diagram in the framer's pocket guide
So all weight bearing walls need squash blocks to transfer the load. And you need squash blocks on both sides? Wouldn't these hold the plywood subfloor up 1/16? And on the gable ends no squash blocks needed so down 1/16? Will OSB rim hold up non-load gable end walls?
In general, web stiffeners are used when you need to fill out the plywood web flush with the top and/or bottom flange of the I-joist.
Squash blocks are used where an I-joist crosses an interior wall where there is also a bearing wall ABOVE it.
The exact terminology and specific details vary from one manufacturer to the next. The place where you buy I-joists from should have an installation/design guide that give their requirements.
Here's a link to GPs web page. There are lots of documents there that can be downloaded:
http://www.gp.com/build/product.aspx?pid=1390
You get an inspection before the ply is laid? Have put web stiffeners in when using only TJIs on gable ends,over bearing walls although inspecter says squash blks. are OK, when TJIs will have hangers on them,etc. As mentioned, read the info.
Most of our plans have an joist diagram,saying where they want point loads,joist/rim board combo,etc.
I didn't do it....the buck does NOT stop here.
Don't squash blocks also need to be grain oriented?...like vertically?
Spheramid Enterprises Architectural Woodworks
Restoring, Remodeling, Reclaiming The Quality..
Absolutely. Otherwise they might be called "swell" or "shrink" blocks.
2x4s nailed vertically= squash blks.Am afraid I missed your point.
I didn't do it....the buck does NOT stop here.
So, I need 2 squash blocks on every floor joist /rim junction? 2X10s may have been easier. GP sells a new "stiff rim joist" that you don't need any squash blocks for? Thanks
Please, read that stuff that came with your I-joists, or download the how-to info from the TrusJoist site.
Squash blocks are typically only needed at concentrated load points. They are not needed at span ends where the rim is picking up load.
Were your floor frames engineered by the I-joist supplier? Most all jobs using them are done this way, and the prints always call out the location of squash blocks. That's how Tim's inspector knows where to look for them.
Was your job not engineered as described? Are you simply substituting them for sawn lumber framing, and laying things out where you like?
No, they are going to be laid out by a truss company. I just wanted to get a big jump on the cut list. So, I am try to understand more of the rules than are probably needed. I could just wait and follow the instructions.
Here ya go. http://www.trusjoist.com/PDFFiles/2030.pdf
Why wait? Print it out, and now you have some bedtime reading.
Detail CS on p. 9 and B2 on p. 10 show the crushers.
Enjoy!
I beam joists can save a lot of time running joists on a floor system because of extended lengths, less weight, etc. and this is often touted as a time (labor=$) saver, but I'll tell you, by the time you install all the web stiffeners and squash blocks specced out on the engineered plan, you don't save much! It's tedious work.
But I do think you end up with a superior floor deck, if designed properly. Glad you are not winging this without the plan.
"So, I need 2 squash blocks on every floor joist /rim junction? "
I've never seen an I-joist manufacturer that required that. The typical 1" thick rim board is good for something like 2,000 PLF. That's plenty for most any residential situation. (Although local codes could require just about anything)
Squash blocks are used at INTERIOR bearing walls. And only if there's another bearing wall stacked ABOVE the I-joists.
If you're getting these from a truss company, I'd be very surprised if they wouldn't give you an installation guide if you asked.
I can do anything you want me to do so long as I don't have to speak. [Linda Evangelista]
Thanks, that is what I thought. The 1 1/8 rim has to be good for something. I will ask for the installation guide just so I am not reading and then building....not fun.
Tiz,
We have to have an "under floor" inspection before we lay any subfloor. Can be a huge pain.
The inspector in the city limits told us if he's not there, go ahead and start sheathing. County is a different animal.
Generally speaking, web stiffeners are provided to give the TJI some meat to nail into (e.g. hanger, blocking, etc). Squash blocks carry a point load. Both of these are used in an engineered wood-I floor system.