Squash Blocks

Fellow Inspectors,
Hard to tell from the pics, but all the blocks were undercut a bit to much.
New construction $700K




For another $150K they can have shims installed.

Any detail on the prints?

The blueprints were not available. I know the blocks are wrong. They are supposed to be 1/16 longer than the I-joist. Funny this was, the other beam had the blocks installed properly.

Anatol, The joists are not resting on the plate, but it looks like the blocks are. Maybe that’s why there’s a gap at the sheathing.

Yes, yes they are.

Good catch.

Many homes have no squash blocks at all installed when TJI"s are used. Who requires them to be 1/16" long, why and under what conditions?

Kenton, typically it’s when there is a load bearing wall above that the blocks are needed. All manufacturers that I’ve used specify that they be 1/16" higher that the joist.

I figured, Larry. Then they must be detailed by the engineer that stamps the plans. Is the +1/16" rule something required by I-beam manufacturers? Does that hold true whenever squash blocks are used in i-beam floor systems?

Yes, the I-joist manufacturer specifies the need and location on the installation instructions.

Ah-HAH, thank you.


good booklet dealing with I-Joist specs

see page 5

Slightly off-topic, but you have a $700K house here and they used OSB? Cheap man, cheap!

Here where I am located $700,000-$1.5 million houses are a common thing and we always use 3/4 in TG OSB. That is the norm here. Its all about the bottom line. A couple years ago when 1/2 osb was almost $20 a sheet some houses only got the sheer panels sheeted. The other places on the house got black fiber board. I also saw no sheeting above and below the windows. The stucco guys would just put their foam and wire over it and procede like normal. I’m not saying its a good thing, but it does happen from time to time.

not all OSB is cheap
and the good stuff is way better than plywood
wet construction weather like we have had this fall doesn’t harm it
it doesn’t warp,blister, peal, separate, stays nice and flat.
the only down side is it is very heavy to handle during installation

I guess the squash block issue is settled.

On the walls? Even in areas with seismic problems like Southern CA 1/2" has been considered overkill because the critical connection and highest potential area for failure is nail shear. Chances are that the nail connection will fail before the wood panel (3/8, 1/2 or 3/4" plywood or OSB) fails.

People often assume in building something, more is better, but it only holds true with your own bank account.

Personally, I dont like OSB. Many years in construction have taught me this.
Up here, it is cheap and widely used. I have a roof to replace sometime this month, when I can get to it, where the sheathing has swollen up to a thickness of over 1". I have seen swollen osb on subfloors. On a roof, I dont like the slippery slope, would rather have plywood.
I am in the process of building my own home, plywood on the subfloor, 1/2 inch plywood on the roof, osb on the outer walls.

My views only

Would that be because it went from 1/2" to 3/4"? ha. ha.

Marcel :slight_smile: :slight_smile: :wink:

Pardon my ignorance. What are ‘squash blocks’?

**Squash Blocks
**Sawn pieces of lumber to be nailed to each side of an I-Joist at the location of a post, load bearing wall, or concentrated load up to 4000 pounds. The squash blocks are cut 1/16" longer than the depth of the I-Joist to insure proper load transfer.

Hope this helps