LVL's USED AS FLOOR JOISTS

[PT99]

Special Inspection
For a typical frame one family home, floor joists are LVL's at 16" o.c., with no blocking. The GC seems to think that the usual blocking at 8 ft spacing when used with lumber is not required for LVL's. Any chance he is right? I doubt it.

Also, on this same job, no blocking was installed for panel sheathing where the panels meet as laid out horizontally.
So clearly there is no nailing on the horizontal perimeters. Sheathing is only attached to the studs.

Aside from where it would be clearly be required for shear walls, is it also required where the wall is not part of the calculated a shear wall system?
These framers say that they never do it, they say I am the first inspector to tell them to provide this.

I know these questions should be addressed to the design professional of record, (it's not me) and I have asked him, but I don't think he really knows the answers.
I just want to hear if I am wrong on this.

 

[phamENG]

1) LVLs as floor joists at 16" o/c rather exceeds my definition of a "typical frame one family home." That being said, the stability of an LVL is going to be essentially the same as the stability of a sawn lumber joist. If the code and/or drawings say it should be there, put it in.

2) Even shear walls don't always need this. There are design capacities for both blocked and unblocked shear walls in the NDS and supplements. So no, it shouldn't be required in non-lateral framing unless specified by the EOR for some reason.

 

[NorthCivil]

>I know these questions should be addressed to the design professional of record, (it's not me) and I have asked him, but I don't think he really knows the answers.

why would he not know the "answer"? his design, his baby.

Floor joists don't always need blocking. sheathing doesnt always need blocking at joints. this is case specific for the particular design, not an issue where one rule fits all.

 

[phamENG]

NorthCivil - doesn't know the answers because he didn't design it. He gave it to a graduate engineer/EIT to design who ran the "analysis" in a free wood software program, just slapped on some typical details, and sent it out. 1 Project down, 10 more to go today...

I've seen (and sadly been part of, very early on) several residential jobs go that way.

 

[r13]

......, but I don't think he really knows the answers.

His knowledge is not up to anybody to judge, go ask him.

 

[msquared48]

Horizontal structural diaphragms do not always need to be blocked, but I have never designed a wood shear wall that was not blocked. GWB and GSB shear walls are different animals though. I have always used the UBC and IBC rather than the IRC for lateral design as they are more conservative, giving more existing capacity when the ever present mistakes are made. And if the wall is not a designated shear wall, horizontal blocking is not required.

As for the 8 foot spacing for blocking of the LVL’s, I would do it unless the Truss Joist manual specified otherwise. Remember that the blocking is not only to provide lateral support to the bottom flange, but also to better enable load sharing between adjacent joists - commonly referred to as bridging.

Sounds like the contractor is just trying to save time and money at the homeowner’s expense. “This is the way I have done it for 30 years” does not cut it with me.

Mike McCann, PE, SE (WA, HI)

 

[PT99]

Thanks for the replies,
We will see what the AOR comes up with.