Is it okay to lower joist hanger?

[Kobolt]

Hi,
I need a quick confirmation that I'm thinking correctly.
I'm going to build joists for the bathroom floor and want to lower it to reduce the level difference between the floor in the adjoining room.

It's a bit special, but I think it should work. My question is whether it's okay to hang a joist hanger below the beam as in my sketch? The beam consists of two screwed together (maybe glued) 45x170. This is so the joists can be free from the wall.

Comments?
// Kobolt

 

[Matti_75]

Yes, you could do that if you use longer joist hangers. Then you will have the same number of screws/nails in the bärlinorna.

 

[Kobolt]

That's right, I looked up the sizes and there is one that is 197mm. Thanks for the tip.

 

[vojma]

Another option is to notch the joists a bit at the ends.

/Vojma

 

[Kobolt]

I have the impression that it is a worse option? But I will do it on the other side over a partition wall and then let the floor joist continue to the final suspension.

 

[Matti_75]

Another option is to notch the floor joists a little at the ends.


/Vojma

Then you lose load-bearing capacity in the joists.

 

[Kobolt]

That's what I meant, I'll treat myself to a joist hanger on the opposite side as well.

 

[mattiasp]

Then you lose load-bearing capacity in the studs.

Very marginally. There are only shear forces at the ends. The bending moment, which is what dimensionally determines the beam, is usually maximal in the middle of the beam. Neither the load-bearing capacity nor the deflection is significantly affected by notching the beam at the bottom at the corner.

 

[Granngubben]

I've got the idea that it is a worse alternative? But I will do it on the other side over a partition wall and then let the joist continue to the last suspension.

It is not a worse alternative to notch at the beam end, the bending moment is zero at the end and the shear capacity is not significantly reduced.

However, it is questionable to notch at a mid-support if the joist is continuous over the partition wall. There, both the bending moment and shear force are at their maximum!!

 

[Kobolt]

If I notch out just as much at the midpoint support, which is also a load-bearing wall, and fasten it properly to the wall, there should be no difference compared to having two separate beams with beam brackets that are notched at each end, right?

 

[Granngubben]

If I notch out as much at the midpoint support, which is also a load-bearing wall, and firmly attach it to the wall, isn't it essentially the same as having two separate beams with joist hangers that are notched at each end?

A continuous beam on three supports is much stiffer than two separate beams.

 

[Kobolt]

I think you misunderstand me, I have a span of about 4 meters. I can divide it into 2+2 meters with joist hangers at each end (i.e., 4 joist hangers) or alternatively notch the underside of the 4-meter beam in the middle about 50mm and attach it there. There should not be any direct difference. The deflection must be less than having a 4-meter beam on only two supports.

 

[Granngubben]

Let me clarify a bit:

A 4 m long continuous beam on three supports is MUCH stiffer than two separate 2 m long beams!
If you use a 4 m long beam, you have the opportunity to achieve a stiffer floor if you don’t notch out (too much) at the center support. Can you notch out the wall instead? This wasn't really your question, but I couldn’t resist commenting on the big difference between the two options, (will come back with some numerical examples if I get time). If you notch out in the middle, you get something between a continuous beam and two separate beams.

Regarding your original question about notching at the beam ends, it's a good solution.

 

[Kobolt]

Thanks for the good answer, I aim to notch out in the wall as much as possible and out in the beam end so that the beam shoe can be attached normally!

 

[Kobolt]

Just wanted to let you know that it worked well!