Attaching a deck ledger to a ladder truss

[shane]

I have been asked to review a deck ledger to ladder truss attachment for a house that was constructed in 2021. The truss layout and truss details show a ladder truss along the exterior of the house, where the 10 ft wide deck is, and the truss is fully supported by a CMU wall. The truss manufacturer provided a ladder truss with SYP 2x4 verticals at 16" oc and the contractor attached the ledger to the truss, through the sheathing, with (2) ledgerlok screws at each location. Each screw was verified to have hit the corresponding vertical member completely. The truss company is using 2015 IRC/TPI2014 for their design.



As part of my review, I have found reference attachment details from MiTek and the SBCA that show the verticals being 4x4s instead of 2x4s. I understand key blocking adjacent to the existing members could have or likely should have been done; however, there was no reference it being needed in the truss package so it wasn't. Is key blocking or the use of 4x4s a code requirement or is that the suggested practice?

Should the truss manufacturer have included 4x4s in the trusses those for this project or is that something the builder has to request when ordering?

Thanks
Shane

 

[RontheRedneck]

I have never heard of using 4X4s in floor truss ladders.

It's certainly possible. But this thread is the first mention of it that I can recall.

 

[XR250]

What is your concern? Screws not being centered (valid) or webs pulling out of the truss?

 

[KootK]

Should the truss manufacturer have included 4x4s in the trusses those for this project or is that something the builder has to request when ordering?

Currently, I would say that it is something that the truss manufacture would have to be directed to do if there is an expectation that they do it. The cost of using 4x4's instead of 2x4's is too high to expect the truss suppliers to do that voluntarily if their local competition isn't doing the same.

That said, mandatory 4x4 is a great idea in my opinion. I've seen some awful results when lag screws have been installed into the narrow face of 2x members blind. And I sympathize. Were it me doing the work myself, I'm sure that it would be a hot mess. At the least, I like to use GRK screws instead of lags when they work. Predrilling can help but that tends to be a big ask.

 

[shane]

Thanks for the different responses.

XR250 - yes, there is some concern over what the screw diameter is and how centered the installation is. A centered LedgerLok in a 2x4 would give you ~2D +/- of edge clearance where keyblocking or a vertical 4x4 makes all that a non issue

KookK - I have reached out the truss designer to see what could or would trigger using a 4x4 vertical

 

[XR250]

Thanks for the different responses.

XR250 - yes, there is some concern over what the screw diameter is and how centered the installation is. A centered LedgerLok in a 2x4 would give you ~2D +/- of edge clearance where keyblocking or a vertical 4x4 makes all that a non issue

KookK - I have reached out the truss designer to see what could or would trigger using a 4x4 vertical

I mean Simpson has tables for this but they do not give an off-center tolerance AFAIK.

 

[phamENG]

Those 4x4 things, or key blocks as you rightly referred to them, are used when the ledger is perpendicular to the trusses. They're usually built up out of a pair of 2x4s or cut from a 4x4 to provide supports where your truss spacing and doesn't match the fastener spacing for the ledger. here's a snip of an old detail I started to draw up once upon a time:



In this case, though, there's no issue. It's no different than fastening a ledger to studs at 16" on center, except that they're shorter have more capacity than a 10' tall stud might.