Levelling an uneven wood subfloor in a flat

[Doughman]

Hi everybody,

I have read the very informative stickied post by mattysupra about leveling an uneven wooden subfloor. Things that make it tricky for me are people describing it acting almost like water. I have had issues before with leaks, water trickling down the joints of the chipboard (or in the old nailholes in the original chipboard) in my subfloor and damaging my neighbour belows ceiling. I absolutely want to avoid this happening again. The stickied guide advises using caulk to plug but I am just not 100% that it would be possible to plug every little route down below.

I had half the subfloor ripped out and replaced a while ago but it has not been made level with what was there previously. I had the idea to put down thin ply at the worst bits (5mm or more) and sheet ply over the top of all this although this seems like a far from ideal solution. I should say that I intend to put down vinyl click board flooring after this. The whole area is 1750mm x 1350mm.

Is what I have started doing going to be nowhere near adequate enough?
Should I definitely be looking at a self leveling compound and if so how can I make absolutely sure of it not dripping below?
Is it better to have the toilet not resting on the click flooring and simply silicone sealed round, or to take it out, install the flooring and place it back in above the vinyl?

http://ceiling2floor.co.uk/product/wpc-vinyl-click-woodplank-white-oak/ is the product I was looking at.


Other smaller queries I have are:
What is the best way to remove the toilet without leaking water to enable me to work on the floor?
The information I can see from vinyl click boards all describe it as waterproof. Does this mean it absolutely will not have water penetrate it or just that it won't be damaged by water? I am very cautious about ever having water damage issues again, especially in unseen places like that.

Thanks for reading and I look forward to seeing what you guys think.

 

[vinn]

Your layout and first fix plumbing looks terrible - is that how things will remain?
The WC and probably the door will have to be removed from the room - is there anything else in the room thats not in the pics?

Isolate the supply to the WC & flush - then use a sponge to empty the cistern.
Wearing gloves, use a container and a large sponge to remove all water from the pan.

After all the flooring has been lifted and the joists exposed post a pic.

Have the shower waste, and shower valve & supplies, been water tested?
What kind of enclosure will you have?

 

[Doughman]

My layout was switched around as the door was hitting the toilet. The toilet and sink were swapped (sink not yet fitted, supply and waste pipework shown through the gyp).
There is nothing else in the room that is not in the pictures, It is a very small room.

I managed to remove the WC last night but as it's hooked up to another WC in the house on the same level, I found out to my cost that when the other is flushed it floods this open end. So the toilet has been put back into place until I know exactly what I am doing with the flooring.

I don't think I can lift all the flooring as the chipboard goes under the walls, one of which has now been tiled.

Will I have to choose between self levelling compound or ply? The ply that I have put down already has a large dip as well from where the WC used to be (9mm at it's worst). Should I be packing ply underneath this sheet to level it or is it better to apply self levelling compound on top of the sheet of ply?

I assume the waste and supplies have been tested as a plumber fitted them, not me.

I bought this sliding glass enclosure from amazon: https://www.amazon.co.uk/Homcom-Sliding-Enclosure-Bathroom-Cubicle/dp/B013OHMU7G

 

[Doughman]

 

[Lower]

As its such a small room I would lift the whole floor and replace with a single piece of 18mm or 25mm wbp ply. That will give you a perfectly flat floor with no joins for you to worry about. However, the floor covering should be the waterproof bit. If water is getting under the floor covering you will have problems with the floor anyway.

You can get a bung to put in the toilet waste pipe whilst the toilet is out to stop the leakage when other toilets are flushed.

 

[Doughman]

Just to clarify, you would lift the chipboard and have just thick ply on the joists?
I don't think i would be able to get one sheet in that size to enable me to forget about joins.

The bung is a good idea, I'll have a look for one.

The floor covering is going to be vinyl click boards. They state they are waterproof but they also state this is under the condition the floor beneath them is level and smooth. Does anyone have any recommendations for which particular type to go for as there seems to be a lot of options?

 

[Lower]

Yes, ply straight onto the joists. Remove the whole of the existing and replace with the ply.

Looking at that size of room, you should be able to do that area of floor in one piece, and if not in one piece you could certainly do it in two which will be much better than trying to make good the mismash of what's there now. I've done a much bigger bathroom in 2 pieces to give a solid base for travertine tiles. You'll need to take the toilet out and remove the door but otherwise it should be fairly straightforward as long as you have a decent jigsaw.

Why specifically go for Vinyl click boards? Ease of fitment or the fact that its largely water resistant?

 

[vinn]

OP,
The odds are that you are heading for more difficulties - the plumbing is rubbish, likewise the jig-saw puzzle of a sub-floor.
eg. the WC connection will leak, & having another WC discharging/flushing into your WC wont fly either.
Access to the shower waste & trap is blocked by an off-cut used to support the tray.
Have you had your full body weight on the tray?
You must test everything water before going any further.
Why have the rad flow & return been fitted like that?

A 9mm dip suggests that a joist is missing or damaged.
Flooring can be cut right up to a partition - typically, noggins are used to pick up loose edges.
Make a template, and cut ply to the template - then drop the one piece of ply into place.

The sliding shower door is a good idea - if its a complete unit. You must fit it and water test it before doing anything else - just in case it leaks.

To be honest, If you can afford it, you would be better off with a bathroom fitter coming in?

 

[Doughman]

At the weekend, I took off the door and removed the toilet. I then lifted all of the chipboard and it revealed the following :

so I decided to put in some new wood across the subfloor to act as joists which would allow the chipboard and then the ply on top to sit level:

After that I put down 3 lengths of chipboard across the width of the room and nailed sheets of plywood down. It now looks like:

I have a guy coming tomorrow to install my shower, shower door, sink and flooring. I bought the click flooring from Wickes : http://www.wickes.co.uk/Westco-Caspian-Grey-Oak-Luxury-Vinyl-Flooring/p/141396 . It looks pretty easy to fit.

I do plan to ask the guy about the off-cut that supports the tray blocking the access to the trap. After he has finished up I just need to decide how to decorate the exposed plasterboard, and what to cover the gap under the shower tray with (something that can be removed in future preferably). Does it look from that last photo that my best bet is to have the plasterboard patched, skimmed and painted or is that not the best idea seeing as it could get wet from time to time. Is the PVC panelling stuff the way to go?

 

[vinn]

Your photos have not come through?

 

[Doughman]

Your photos have not come through?

My bad, fixed now.

 

[vinn]

You dont want new fixtures fitted until you have sorted what you already have to do in the room - such as painting and tiling behind the basin and WC.

What looks like battens fixed on top of ply - is that in fact battens or joists and battens?
There appears to be minor wet rot damage.

The WC spigot - is it now higher than before?
When a plumber or bathroom fitter does come on site then have them fix the WC issues.

Plasterboard is fine - no need for more backer board or PVC panelling.

 

[Doughman]

I think once the Click-fit vinyl plank flooring is down the WC will be sitting higher than originally. I will say to the plumber if he can fit something better to seal - is a flexible fitting the way to go?

It looked like battens laid across the under the chipboard were supporting the subfloor. I suppose the joists are under these again. Some of the battens had been damaged like you said, which was resulting in sags and an uneven floor. The floor is all smooth and level now on 6mm plywood shown on the last photo.

I don't plan to have anymore tiling done in the room, only having it in the shower enclosure. I was asking what my options are for the rest of the room. Do I need to have the plasterboard on the walls, and behind where the WC is going skimmed etc before painting? Or if I was going to put PVC panelling on them (like http://ceiling2floor.co.uk/product/5mm-white-ash/) would I need to do anything to the plasterboard before installation?

 

[vinn]

A plumber could easily sort the pan connector issue out eg. using a MultiQuick 18mm or 40mm offset connector or similar. IMO, avoid flexi connectors.
But there's still the back to back WC outlets issue?
The wall will have to be patched and taped and skimmed before painting - or use the PVC panelling (I dont know anything about such stuff).