Looking to strengthen loft joists...

[Adam182]

Hi everyone, thinking about strengthening up the loft floor joists now that all the lath/plaster is off.

I won't be doing a loft conversion with stairs but I will be making it good for a bit of a mancave if possible.

I've noticed the Joists don't actually sit on the external wall itself but rather hang off the rafters, the opposite ends sit on a central brick wall and a new beam runs above the next room and fixes to the opposite side rafters in the same fashion.

Would it be possible to just fix 7 x 2 to the rafters on the other side of where the current joists are fixed? then remove the current joists one at a times i go?

Any feedback is much appreciated.

 

[John D v2.0]

You need the most shear strength at the ends ie the rafters and the connection and the least in the middle. The opposite applies for bending strength, the middle needs the most.
If you're not getting an SE to look then best thing is to rest the new joists directly on the wall. If it's light storage in the loft then hanging off the rafters would do but you need some joist hangers rather then just screwing the ends in.
If your man cave includes anything you can't carry in one hand eg furniture etc, you're going to blow any reasonable weight allowance in no time

 

[Adam182]

You need the most shear strength at the ends ie the rafters and the connection and the least in the middle. The opposite applies for bending strength, the middle needs the most.
If you're not getting an SE to look then best thing is to rest the new joists directly on the wall. If it's light storage in the loft then hanging off the rafters would do but you need some joist hangers rather then just screwing the ends in.
If your man cave includes anything you can't carry in one hand eg furniture etc, you're going to blow any reasonable weight allowance in no time

Thanks for the reply John, much appreciated.

Had the Building Control Officer round today, he said I could sister the joists with 7x2 which is to regs spec for the span BUT it would add stress to the rafters which would be far from ideal. He also said for it to be good for a future loft conversion anyway it would require a beam and an SE for calculations, the cost would be pretty substantial considering it might not actually even get converted in the end anyway. He said if it were him he would just leave the joists, reboard and be mindful of what I put in the loft.

So as of now I'm just going to reboard the loft with some t&g boards and just use the loft space for storage and maybe a light chair/wall mounted tv.

 

[Ian H]

So as of now I'm just going to reboard the loft with some t&g boards and just use the loft space for storage and maybe a light chair/wall mounted tv.

Are you not allowed to watch porn in the lounge away from the cold and dust?