Questions about leveling floor joists

[r91]

Hello,

My partner and I are about to level the floor joists and are currently shoveling out all the old sawdust and pumice that has been used as insulation.

Now that we are going to level the floor joists, what dimensions should we use for the studs? We plan to screw new studs onto the existing ones on the side. The current studs are 180x60mm. The center-to-center distance between the joists is 530mm.

Some of the joists have twisted, how should we deal with them? Set noggins and tension them to straighten them? Or buy completely new ones?

Then to the last question, we plan to install load-bearing chipboard flooring with milled slots for underfloor heating, followed by a 22mm plank floor. However, we would like to lay the plank floor along the joists (the room will feel larger), is that okay? If the chipboard is load-bearing? Should we add extra noggins?

Here's how it looks right now:

 

[brumbjorn]

You can straighten it with noggins if that's enough. However, check if the floor is even. A maximum of 5 mm over 2m is allowed. It can be a hassle to level the floor after the chipboards are laid. Better to align the joists. Check the laying instructions for the floorboards. If they are screwed and glued, it should hold for all directions of the wood, but I'm not sure.

 

[fribygg]

Now that we're going to level the floor joists, what dimensions of studs should we use?

45*170mm seems simplest if it suffices for the span of your floor joists.

 

[pjkw]

If you are just leveling, you just need timber thick enough to screw it in, 45x95 should be perfectly sufficient. And the direction of the final floor shouldn't matter.

 

[lärjungen]

I screwed on 45x70 when I aligned our floor joists.

 

[r91]

The floor level difference is at worst 45mm, so I guess I need at least 45x120mm studs to level it?
Since the old studs are screwed in, I'm considering shimming the studs so that it becomes horizontal.

 

[brumbjorn]

If the floor height varies by 45 mm and you need to level it, you can loosen the screwed joists and attach them at the correct height. Alternatively, you can install new joists parallel and in contact with the existing ones. Just keep in mind what the new height will do to doors and thresholds. Shimming involves placing small shims. You probably shouldn't do that.

 

[pjkw]

The floor level difference is at worst 45mm, so I guess I need at least 45x120mm joists to level it out?
Since the old joists are screwed, I’m considering shimming the joists so that it becomes horizontal.

45x95 is probably still enough I would guess, you can also use different ones depending on how much that particular joist needs to be raised. If it's very high at just one spot, you could consider planing down that specific joist locally to avoid raising everything by 45mm.

I would probably rather try to straighten the old joists with blocking rather than shimming the new ones.