Thread: Repairing bathroom floor

When I renovated our bathroom a couple of years ago I tiled the floor over cement sheets nailed onto a timber floor.
I lifted the toilet and tiled underneath it but tiled around the vanity unit ( inside the unit is the dirty clothes chute to the laundry underneath ).
I tiled around the shower recess and grouted against it and have not had any problems at all.
Just make sure the timber floor is sound and the cement sheets are properly nailed down.

Peter

In my last largish renovation, the attic (6x12 m) ended up with a new toilet in it. We could have used 19 mm compressed fibro on the joists but we opted to glue and nail a special (6mm I think) compressed fibro built for this purpose onto the yellow tongue flooring.

Even when we followed all the manufacturers’ instructions and used a kilo of nails for all the spots marked for that purpose, we now have a beautiful new toilet with two cracks that wander across 4 of the floor tiles in two different places and directions.

I don't trust tiling timber floors anymore, regardless of the many different and creative ways people will tell me it is guaranteed to work. Too many variables in a wooden floor, new or old and tiles are everything but flexible.

Having said that, and if you want to take the risk, it is clearly a question of money. How much do you want to spend?

You probably know that the "proper" job is to rip out every existing bit that is attached to the floor, cut out all the flooring to lay bear the joists and place a 19mm compressed fibro slab on them, apply a good brand water barrier, two coats in two days acrylic with fibreglass reinforcement, proper edge at the door, and then floor tiles.

How many corners do you want to cut from there?

Well to start with I wouldn't skip the membrane, besides the fact that it is a council requirement, it is the only way to minimise water damage (not stop it completely mind you).

Do not use ordinary fibro sheet, the difference in price with the compressed fibro is well worth it, and put one (galvanised) nail in each of the dots marked even if someone tells you, that you are nuts.

As for the question to go under the shower or not . . . . . think that the shower is the source of 90% of the water damage in a toilet, I wouldn't worry too much about the toilet bowl and basin providing you have a good water membrane in place but under the shower . . . If you ask me I would make the extra effort to do it.

Last but not least, check the quality of the tiles, ask an expert and check for factory run-out, the difference in price is big and you may get high quality at very low price.

Good luck!

Just adding to what Marc said, when ordering your tile adhesive and grout make sure you specify that you are tiling on a timber substrate. You will need to get an adhesive & grout combination that are flexible.

Mick

Mick,

As indicated I had no problems, in fact I have tiled a large kitchen, pantry, two bathrooms and entry hall.
So I am wondering does it make a difference that my floor is a hardwood tongue and grove and has been laid down about 45 years ago rather than yellow tongue flooring.

Peter.

All other things being equal a 45 yr old hardwood T&G floor is going to be stiffer and less likely to move than a structafloor one. However IF the structafloor is laid right, and the subfloor is sound and at the correct spacing then there shouldn't be any problems laying tiles over it.

Mick

I think you are right, hardwood floor should be stiffer than a new particleboard floor. However the one in question had 10" joists at 1.5' distance and still . . . .crrrrack

Marc, sorry about your floor but something somewhere must not have been 100% right. The bible (Australian Domestic Construction Manual) says it can be done and I've seen plenty of good tiled floors laid on a timber subfloor. I've also seen a few tiled floors on concrete slabs that have cracks, but not as many as on timber floors. Obviously there's less room for error when laying a non flexible flooring (tiles) on a flexible subfloor (timber).

John G, I would recommend running your full waterproof membrane 20 mm up the side of the fibreglass shower enclosure, as well as up the walls at least 50mm. You can cover this with your skirting, preferably a tile skirting. If you are worried about tile cracking, and it's a definite possibility if you get subfloor movement, there are alternatives you may want to consider: welded vinyl (you can get some really cool colours and patterns in the industrial welded vinyl range, but it's not cheap); cork; or small mosaic tiles (any subfloor movement will generally crack the grout rather than the tiles).

Mick

Thanks for the responses.
What is welded vinyl? Obviously not linoleum....?
Do normal tile suppliers stock it?

Linoleum is not used much nowadays, it's made from linseed oil, fine sawdust and a few other things I can't think of just now. It's been mostly replaced by vinyl, either in tile or sheet/roll form. In sheet form the seams can be welded together using a hot air gun and a filler rod of the same material. This type of flooring is widely used in commercial situatuions like hospitals, schools and laboratories. Any good flooring supplier should be able to help you. It can be coved up the walls, or it can even run ruight up the walls to the ceiling but this looks a bit too industrial.

Mick

Stripping everything out and putting down 19 mm compressed sheet is probably going way beyond what you want (or need) to do.

Provided your timber floor and sub-floor are sound you should not have any problem tiling over a properly fixed 6 mm cement fibre sheet. Check that all bearers and joists are as they should be (packing if necessary) and there is minimum "bounce" in the floor. I think the spec sheet for Hardies ceramic tile underlay gives a recommendation on maximum permissible deflection. Don't skimp on the fixings and use a trade quality flexible cement based tile adhesive.

Not sure what Mick means about about waterproofing up the side of the shower enclosure. Does mean this across the floor outside of the shower and then 20 mm up the shower base? You would need to put some sort of skirting around the shower base to hide the membrane.

Good luck. What you propose is certainly do-able.

George

When I renovated our bathroom several years ago I tanked the entire floor with a bituminous sealant, then tiled over that.
It waterproofs the whole floor and is flexible

George, you're right about what I said about the membrane. At 20mm though a skirt shouldn't be neccesary. By the time you get the tiles bedded on adhesive and a generous bead of sikaflex (colour matched to the grout) it'll all be neat and unnoticed.