blocking benefits 1

[skavuvie]

if you have a typical wood stud shear wall 10', 2x6 16"oc with a (ledger connected to it carrying joist) lets say mid height of wall for the sake of example. what would be the advantage of adding blocking in between the studs where the ledger is connected. does that increase the shear capacity of the wall where the ledger is at? i am trying to figure what the benefits of the blocking are and could you go without blocking? i am assuming that it increases shear capacity but maybe i am wrong.

 

[Lion06]

It definitely feels better for dragging the shear into the wall.

 

[dhengr]

You increase the lateral load capacity of the shear wall, by blocking all of the joints of the sheathing, and by increased sheathing nailing. Why not platform frame your wall and floor system? The joists sit on the top plates and the 2x ledger member is used as a rim joist and the ledger connection to the studs goes away, and there is no need for blocking. On taller walls blocking is req’d. at some point for fire stop blocking.

 

[msquared48]

"does that increase the shear capacity of the wall where the ledger is at?"

It probably does, but nothing the code allows you to specifically quantify. I would install the blocking to prevent the studs from "rolling over" as it were, from the lateral forces from the floor diaphragm. It's just a good practice.

It will actually serve as fireblocking too, which is a good thing.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msquared48]

In re-thinking this, assuming the shear below the floor being larger than that above, which would be expected, the addition of the blocking for the purpose of edge nailing for the adjoining shear walls, would increase the capacity of the lower wall if tighter nailing was used in the lower wall. However, if no additional nailing was used below the floor, no additional capacity would be realized.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[skavuvie]

thank you for your responses. i am understanding from the comments that it divides the upper and bottom half. let say by using 3/8 panel 6 inch E.N. gives me 230 plf at roof level but if i increase the E.N to 4 inch it would give me a shear capacity for the wall of 360 plf at the ledger and blocking level, thus dividing the shear wall into two different shear capacities, 230 at roof and 360 at ledger level.

 

[msquared48]

Yes.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

One other reason for blocking, particularly in multifamily construction, is to provide full blocking behind drywall joints. This is a fire code issue.

Most drywall subcontractors like to place drywall horizontally for ease of placement and less waste. That leaves the horizontal joint unsupported except at the studs. The fire rating is based on the drywall having full support at all joints as the drywall mud and tape over a joint do not have the same fire resistance as the board itself. When fully blocked, the combination of the blocking, tape and mud satify the fire resistance properties, typically for a 1-hour fire rated wall.

 

[BAretired]

Ron,

If the wall is 10' high with a ledger at midheight to carry joists, midheight blocking is not going to be at the drywall joint.

BA

 

[Ron]

BAretired...true, but for 10' walls, the drywall can be installed vertically, so it gets full blocking from the studs. If they still want to install horizontally, they'll have to provide additional blocking for the fire resistance.