[wengang1]

Hi all.
I have two rooms that share a girder running along the center line of the house. Basically, the joists from each room come to rest on top of the girder, get nailed together, and then get a 13" blocking piece put between each pair.

Because of existing wiring, and because I just bought a framing nailer limited to 3.25" nails, I want to instead put a 14.5" blocking piece between the joists in both rooms just a few inches out from the girder on either side.

Doing it my way will put twice as many blocking pieces, so that should be better, but it will also allow me to shoot the nails in rather than manually hammer 5" nails through two joists into the blocking piece on each side.

Question is, is that allowed, or is there a requirement to block specifically over the girder (made up of three 2x10s nailed together and resting on cinderblock piers).

Thanks.

 

[chandler48]

You can do it your way with your new toy, or you can toenail the blocking into the joists with your new toy. Either way you won't have to pound nails.

 

[Nealtw]

Code says bridging no more that 7 ft from support or from each other.

The only time we see blocks there is sometimes with TGI joists

We have put the odd block in there if the joists are leaning over just to keep them straight. Just to make floor sheeting easier.
There would be nothing wrong with toe nails with 3" nails
That space will want to be used for plumbing, HVAC and electrical

 

[Yodaman]

Cross bridging keeps the bays open for wires and smaller pipe to pass thru

 

[Old Thomas]

Sometimes blocking is installed where a bearing wall is heavily loaded and located over the beam. They help distribute the forces.

 

[Nealtw]

Sometimes blocking is installed where a bearing wall is heavily loaded and located over the beam. They help distribute the forces.

Not needed if the studs are above the joists and a few blocks under point loads.

 

[Calson]

Blocking prevents twisting of the joists and makes them better able to resist the loading from the floor above. The spacing depends on the joist and the length of the span but puting blocking in at 7-8 foot intervals is a bare minimum. Proper support will also reduce problems with a squeeky floor later.

Load tables are available online and your local building and permit office may have information. In most locales the building permit requires plans that would include a framing plan with blocking and other details specified on the plan.

 

[P C D]

Hi all.
I have two rooms that share a girder running along the center line of the house. Basically, the joists from each room come to rest on top of the girder, get nailed together, and then get a 13" blocking piece put between each pair.

Because of existing wiring, and because I just bought a framing nailer limited to 3.25" nails, I want to instead put a 14.5" blocking piece between the joists in both rooms just a few inches out from the girder on either side.

Doing it my way will put twice as many blocking pieces, so that should be better, but it will also allow me to shoot the nails in rather than manually hammer 5" nails through two joists into the blocking piece on each side.

Question is, is that allowed, or is there a requirement to block specifically over the girder (made up of three 2x10s nailed together and resting on cinderblock piers).

Thanks.

All joists have to be fully blocked (with 2x10s in your case) at their supports. If you can fit 13"-long blocks anywhere on top of the girder without nails, and then add your nailed 14.5"-long blocks just short of the girder, that should work.

 

[Nealtw]

All joists have to be fully blocked (with 2x10s in your case) at their supports. If you can fit 13"-long blocks anywhere on top of the girder without nails, and then add your nailed 14.5"-long blocks just short of the girder, that should work.

Is that code where you are, we only need that when it is a cantilever on an outside wall.

 

[P C D]

Is that code where you are, we only need that when it is a cantilever on an outside wall.

I read the Codes as often as I read instruction manuals (I go straight to the Codes' sources.)


Rim joists on typical exterior walls serve the same function to joists (lateral support) as blocking.

 

[Nealtw]

I read the Codes as often as I read instruction manuals (I go straight to the Codes' sources.)


Rim joists on typical exterior walls serve the same function to joists (lateral support) as blocking.

The only reason we do the blocks on the exterior wall is for air stop and have never had to put blocks over and interior wall unless the wall is a shear wall.

 

[P C D]

The only reason we do the blocks on the exterior wall is for air stop and have never had to put blocks over and interior wall unless the wall is a shear wall.

Now I had to look it up:


From IRC 2015
R502.7 - Lateral restraint at supports.

 

[Nealtw]

Now I had to look it up:


From IRC 2015
R502.7 - Lateral restraint at supports.

That is for the rim joist, nothing about interior walls?


R502.7 Lateral restraint at supports.

Joists shall be supported laterally at the ends by full-depth solid blocking not less than 2 inches (51 mm) nominal in thickness; or by attachment to a full-depth header, band or rim joist, or to an adjoining stud or shall be otherwise provided with lateral support to prevent rotation. ​

 

[P C D]

That is for the rim joist, nothing about interior walls?


R502.7 Lateral restraint at supports.

Joists shall be supported laterally at the ends by full-depth solid blocking not less than 2 inches (51 mm) nominal in thickness; or by attachment to a full-depth header, band or rim joist, or to an adjoining stud or shall be otherwise provided with lateral support to prevent rotation. ​

See Exception 2. Isn't BC in earthquake country?

 

[Nealtw]

See Exception 2. Isn't BC in earthquake country?

Like I said, it is called for in a shear wall, but only sometimes as per the engineer responsible. .

 

[P C D]

Like I said, it is called for in a shear wall, but only sometimes as per the engineer responsible. .

Most joists supported by interior beams or walls end at these interior supports, with joist ends from both sides typically overlapping over those supports. Those also require full blocking.

R502.7 Exception 2 is meant for multi-span joists in seismic zones, regardless of whether the supports are shear walls or not.

 

[Nealtw]

Most joists supported by interior beams or walls end at these interior supports, with joist ends from both sides typically overlapping over those supports. Those also require full blocking.

R502.7 Exception 2 is meant for multi-span joists in seismic zones, regardless of whether the supports are shear walls or not.

Anything to do with seismic here is given to the engineer to dictate and inspect and it is very seldom called for. Hhhm