Bathroom project from the bottom up.

[reverend]

Hello
First post so first a big thanks to all regular posters - I have a nice new kitchen!

I'm planning on transforming the bathroom (ceramic floor tiles, wall tiles, new sink and bath) and I'm starting with the floor.

A year ago we paid someone to lay a nice ceramic tile floor (amongst other things) in the bathroom. Well, it was nice for a couple of weeks then the grout started crumbling and the tiles came loose. They were tiled directly on to the floorboards and I don't know what adhesive he used (he just rode off in to the sunset).

From reading the sticky thread on tiling it seems I'm going to have to increase the floor level by fastening 12mm WBP ply on top. I'm going to put a load more screws in the floorboards first as they aren't in a great state (Is it worth trying to scrape all the old adhesive off them?).

My two main questions are.....Will this be sufficient to provide a solid base to tile on? Some of the boards are pretty wobbly/bendy.

Due to limited space in the bathroom I won't be able to use 1 large piece of ply but several smaller pieces. Do I have to leave a small gap between the pieces before I screw them to the boards?

Thanks for any help

 

[Richard C]

As well as reading gcol’s excellent tiling sticky, take some time to read through the Tiling Forum archive posts. I can quote at least 2 recent incidences where over boarding has been either insufficient or incorrectly done which has lead to tile failure. There is a lot of detail in there that will answer many of your questions but come back with specifics if not.

If the existing floorboards are at all uneven, in poor condition or have adhesive all over them (which you must get off), I would remove them & replace with a new floor, 18-25mm WBP, depending on floor construction. It’s more work for sure but the additional cost won’t be much more &, if properly done, you should be guaranteed a perfect & long lasting job. If you replace or overboard, you must use the largest pieces you can manage; I assume your stripping out the bathroom? It’s really the only way to do it. Butt the boards closely but the way you lay them is just as important as how you fix.

 

[reverend]

Hi - thanks for the reply. I've read a lot more posts/threads and have bought the 25mm WBP ply to replace the old floor boards. I've got 1 sheet (8'x4') and a half sheet (8'x2'). The area, including going under the bath is around 7'x6' (with the joists running along the shorter length).

I'm about to start pulling up the floorboards and am unsure if i'll be able to manhandle such a large single sheet (cut to around 7'x4') upstairs and in to position - especially as chances are it will need trimming to fit properly.

Do you think it will be ok to cut the large sheet in to two - making sure the cut is over a joist?

Thank you

 

[Richard C]

Avoid cutting full width sheets if at all possible; you can usually get away with full width boards in a reasonable size bathroom but small en-suites can be a problem. I would lay boards with the longest join down the centre line of a joist, even if it means buying 2 full size boards. Any cross joist joins must be supported by securely fixed noggins (minimum 4 x 2) between the joists; you should also to support the edges of the boards around the perimeter of the room, usually with noggins along 2 edges only but it depends on you joist layout; if under the bath or in a position where it's never likely to be exposed to any loading you can omit them.

 

[reverend]

Ok, I'll try and avoid cutting the big board in half (think I was subconsciously putting off having to take the toilet and sink out!).

I'm using a jigsaw, crow bar and claw hammer to remove the boards and think my best option is a sharp wood chisel to cut the boards at the edges of the room that end on a joist right under/next to one of the walls.

From the small area I've removed so far theres a lot of pipework cut in to the joists. If I'm to lay the large sheet down and screw at regular intervals, do you have any tips as to avoiding the pipework - or is it a case of carefull measuring?

Thanks again

 

[Richard C]

Ok, I'll try and avoid cutting the big board in half (think I was subconsciously putting off having to take the toilet and sink out!).

If replacing or over boarding, it’s always easier to strip to the entire room & there is usually a way up & over most stairways, it's usually the room that restricts you. I would also consider boarding with the longest edge running with the joists as it will avoid you having to fit noggins & considerably reduce the risk of the floor flexing which is enemy no 1 with tiling.

I'm using a jigsaw, crow bar and claw hammer to remove the boards and think my best option is a sharp wood chisel to cut the boards at the edges of the room that end on a joist right under/next to one of the walls.

I use one of these for cross cutting floor boards;
http://www.tools4thegarden.co.uk/product.asp?P_ID=1840
I find it particularly useful for getting tight up against walls & cutting through boards over joists without damaging the joist; watch for pipes & cables.

From the small area I've removed so far theres a lot of pipework cut in to the joists. If I'm to lay the large sheet down and screw at regular intervals, do you have any tips as to avoiding the pipework - or is it a case of carefull measuring?

Many older properties were notched to fit pipe runs but this is strictly controlled by current Building Regs., just make sure you know where they are. I usually mark the pipe/cable routes with red felt tip on the top of the ply as a constant reminder of where they are.

 

[reverend]

Hi Richard - your help is much appreciated! I'm hoping your online because I have no toilet and the sink is being held up with a dog chain attached to the window haha....

I've cut my 25mm ply in to 3 boards to fit the bathroom - each is supported with noggins along their free edges and ive also added some more between the joists for good measure.

Before I start getting busy with my spax screws, I thought I'd mention that my boards are snug against each other and the walls/floorboards that surround them. Is this ok or should I have left some room for expansion?

Thanks agin!

 

[Richard C]

Ideally let the ply acclimatise (store for 48 hours) to the ambient humidity before fixing down but you should be OK this time of year. Seal the back & edges (but not the tile surface) with an SBR sealer. Fit the boards snug but leave a little clearance around the edge of the room if you can but not at the door threshold. I run a line of 50mm GRP mesh plastering tape down the join & smooth over with a little tile adhesive immediately before tiling.