Really basic flooring questions

I'm not an expert but why not just use chipboard with aquapanel, or whatever it is called on top.

Dont bother. Tile it properly instead

The last thibg you want in a tiled floor is flexibility

I'd suggest nearer 40mm

You will need pilot hles in oak yes

Ir use chip amnd tile it as I did.

If you use - and you need to - a thick bed (at leats 6mm IMHO, and up to an inch if the floor is not level) of flexible cement that in itself is waterproof. Likewise if using vinyl that is waterproof too if you seal the edges

I think that before replacing the floor I would try to cure whatever is causing the damp otherwise all you are doing is a sticking plaster job.

Do not use steel screws with oak the acids in the oak tend to rust them away ideally they should be brass, however even with pilot holes driving brass screws into oak is hard work. My old carpentry tutor always advised putting steel screws in first to form the thread then remove them and replace with brass to avoid breakages.

Oak takes screws quite well so I would use screws in the diameters you have mentioned at least 40mm long, too long a screw just involves a lot of hard work driving it in not to mention possible breakages. You will need pilot holes and I would be tempted to use one of those combined drill bits that drills a pilot hole, clearance hole and countersink in one go.

Richard

Put a wetroom-type floor down then you can use anything underneath.

Bill

Make sure they are the same pitch.

Bill

You will need to get the joists close to level to have any chance of lasting success with sheet materials.

I would be inclined to shim out the joists with softwood firing strips cut in to bring out the top surfaces level.

Well WBP or MR MDF or MR Chipboard will usually be fine, although its a good idea to make sure you fix any leaks as well.

With the flooring grade chipboard, it normally has T&G edges, and so can be glued.

If we are talking girth, then 4mm. Then 50mm screws probably (depending on how much shimming you need)

If using a decent self cutting screw and an impact driver, you can probably manage without. However since speed is not really that important for a one off job, then a clearance hole is a good idea. You can get tapered drill bits with depth stop and countersink all built in

- they are good for this kind of application.

Water getting under the lino sounds like a problem to fix first.

If you want a bit more final waterproofing, then a screed of latex self levelling compound could also be used on top of the boards (and would the the ideal think if going for a vinyl plank flooring like Amtico or Kardean.

No. You almost certainly wont.

Most steel screws will shear before they will cut a thread in seasoned oak.

DAMHIKT

Sadly, the joists flex quite a lot when one walks across them.

Then its time you braced them

There is a slope about 2" in 2m in two directions, the joists are about

The original problem was because the bath moved about too much to successfully seal to the wall so my provisional plan is to use a self-supporting shower cubilcle.

So you've got several problems to solve:

1. The joists move, so you'll want to add upright supports onto some of them to stop everything bending around. That assumes that under them is a good hard surface - if not, more work.
2. You'll want to level the joists with shims, or at least get a somewhat flat base to put your floor on, even if it slopes one way.
3. Oak is a sod to fix to. You could perhaps solve 1,2&3 in one go by laying softwood beside the oak.
4. Sounds like you also have a damp issue to tackle.

Oh the fun.

PS don't tile anything that isn't solid as a rock. Do & it'll all come apart after a while.

NT

forgot:

NT

Thanks for the last reference, perhaps I should have looked there first. As to above solutions, non is applicable (except I suppose some subtle shimming) as below the floor is downstairs, which has bare joists not very high and we don't want to change the appearance.

Are floorboards actually a better solution?

How does the height of floor at the doorway compare to the rest of it?

You could lesson the bending by adding some herringbone struts between the joists to force them to load share. That's very good at reducing bounce.

If you can't get level, then flat is the next best thing. However the key point is going to be having the bit with the bath / shower on flat and non moving.

ok so the ceiling downstairs is un-boarded / plastered, and you can in effect see the underside of the bathroom floor?

If that is the case then shimming the floor is still doable, but will take a bit more effort to look ok. Oak firings on top of the existing joists would obviously look better than softwood.

Perhaps some photos would help?

They can better cope with deviations from a plane, although whether that is what you should be aiming for is a different question.

If oak joist flex, there is something seriously amiss. Oak is very rigid.

Is this OK from a fire resistance view point? I suppose less important for a non-habitable room.

I suppose you could hide firrings in a double floor: two lots of 18mm chip. Should aid rigidity.

Ohh. I guess a wonky floor it is then. The floor itself can add a bit of rigidity to the structure, albeit not a huge amount. OSB3 is cheaper than ply, chip is cheaper again. Glue & screw em every 6" if you want to make a stressed box construction - whether that's worthwile I couldn't say from here.

No. Less rigidity, loads of gaps, very smoke permeable.

NT

Did you miss the 4x3" size of the joists?