Questions about Joist hanger strength

[Luke McFadden]

Hopefully this won't be to confusing of a picture to imagine.

So I have a 4 1/2' 2x4. At each end, 3 inches in I have a Strongtie Double Shear Joist hanger holding a 3.5" 2x4. The JH is attached to the long 2x4 with 4 1" wood screws, and then the short 2x4 is attached via 2" woodscrews (which with these JH's go in at 45).

I have two of these 4' 2x4's. One mounted 6" off the ground, and the other 1' down from an 8' ceiling. Attached to this is a 4'x8' frame. So if I set this frame up against the mounted 4.5' 2x4's, the short 2x4's in the JH's fit right inside of the 4'x8' frame. I drilled 3/8" holes and bolted everything together.

So, my question is how strong is this? I'm worried about the JH's. I'm considering putting a top T-plate connector to add some strength.

The load will be between 150 and 350 pounds. Most of the time, the load will be straight down, but the frame will also angle outward from the top section with 2x4 extension, and the maximum angle of the frame would never exceed 35-40 degrees, and would mostly likely be around 10-20 degrees. So, when the wall is at an angle, I'm concerned about the force on the joist hangers, I don't want the small 2x4 to pull out. Would top plates be enough to help this? There are 4 total contact points.

I'm tried thinking of a better way to do this, as far as attaching the small 2x4 pieces to the 4.5' 2x4 section, but I wouldn't. It feels really solid right now, but I've yet to bring it to an angle.

I'd appreciate all thoughts on making this better, and numbers on the strength of the joist hangers (rough numbers are totally fine).

I'm not worried about the 4.5' 2x4 coming out of the wall (3 3/8x3" lag bolts).

Thanks!

L

[John Shuk]

They actually make nails made specifically for joist hangers. I thing they may be hardened.

[Steve Clardy]

They actually make nails made specifically for joist hangers. I thing they may be hardened.

Yes. Hardened, plated, and they fit the hole tight.

[Bruce Wrenn]

Yes. Hardened, plated, and they fit the hole tight.

And required by the building code in most places. No funny looking letter on the head of joist hange nails = a failed inspection, in our neck of the woods.

[Leo Graywacz]

They are N-7, N-8 & N-9 joist hanger nails. They are not hardened. They are a harder steel than normal nails. The difference between most screws and nails in that a nail will bend and a screw will snap. The joist hangers are a system and are designed to be used with nails. 350lb should be no problem for the joist hangers.

[Luke McFadden]

They are N-7, N-8 & N-9 joist hanger nails. They are not hardened. They are a harder steel than normal nails. The difference between most screws and nails in that a nail will bend and a screw will snap. The joist hangers are a system and are designed to be used with nails. 350lb should be no problem for the joist hangers.

Huh, I didn't know about the nails. Will the screws suffice? This is just a personal project and will not remain in the house when/if we move. It isn't anything structural as well, just an "Addition".

L

[Tom Veatch]

...
The load will be between 150 and 350 pounds. Most of the time, the load will be straight down, but the frame will also angle outward from the top section with 2x4 extension, and the maximum angle of the frame would never exceed 35-40 degrees, and would mostly likely be around 10-20 degrees. So, when the wall is at an angle, I'm concerned about the force on the joist hangers, I don't want the small 2x4 to pull out. Would top plates be enough to help this? There are 4 total contact points.
...

Joist hangers are designed to resist primarily vertical shear loads, not cantilevered loads, or loads that tend to pull the joists out of the hangers. I wouldn't be concerned about the 350# maximum load you mentioned as long as it was being reacted as vertical shear.

However, as best I can visualize what you describe, an angled wall, I can see the possibility of a significant moment that would be reacted as a horizontal force tending to either push the joists harder into the hangar or pulling them out of the hanger depending on how/where the load is applied. If the latter case, using a T-connector would be little additional effort/cost for the increased peace of mind. A sketch of the configuration and the loading condition would be a big help.

[Michael Schwartz]

The only concern I would have is the screws you used.

Cheap zinc woodscrews, or Sheetrock screws will snap off pretty easily.

If you are using a good Panhead or Hex head screw you will be in better shape.

Simpson makes a framing screw which is intended for use with some of their connectors, but I am not sure about using it with a hanger.

The biggest thing with joist hangers is making sure that the bottom of the hanger is flush with the joist, and that you don't mangle the hanger up to much installing it.

The Nails sold as Joist Hanger Nails aer going to be Hot Dipped Galvinized, and they are a harder steel and are thicker than a box or common nail and are just a hair bigger than the slot.

Some jurisdictions are requiring 16D nails in hangers now depending on the application.