Ceramic tiles on bathroom floor? Can it be done,and if so why are people so negative? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-14-2005, 02:01 PM
Hi all

This is my first post on here, so please go easy.

I have recently purchased a house. I bought the house knowing it needed remedial work, and this was reflected in the price. I am soon to have a new central heating system (Combi boiler) installed, and at the same time want to renew the bathroom floor. Anyway, back to the tiling points. Of course, when the central heating system is installed, I will then have to relay some sort of floor. Normally in houses here in UK, one would just replace the wooden floor boards with replacement floorboards. However, I am very ambitious, and I want ceramic tiles on the floor. Many people I speak to have said it can't be done. Many have said it can be done, but is very difficult. Some have said it can be done, but the preperation is essential. My head is spinning. I'm very confused. Can anybody help?? To give you some idea, the bathroom is upstairs, and has wooden joists running the length of the house, on which the upstairs floorboards are fixed. This is what the joists are like.





So which timber product or material do I lay on the joists so I can lay ceramic tiles on it. Do I lay chipboard, mdf, new floorboards or some other material. I have read somewhere that this material must be 'treated' before you can lay ceramic floor tiles on it. While researching this topic, I have heard the following comments. Please advise if they are true or false.

"You can't lay Ceramic tiles upstairs in your bathroom, cos the give in the timber joists will just crack them"

"You must not use MDF under ceramic tiles"

"You have to use a special grout"

I would be grateful of any advice on this project.

Cheers all

PS, One last question. Can you drill large circular holes in tiles (For lighting etc)

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03-14-2005, 02:11 PM
We need to know the size, spacing and maximum unsupported span of the joists you have now. You can use metric dimensions, we'll figure it out. :D

To go over your joists, assuming they are stiff enough, you'll want to use plywood. 3/4" (19 mm) plywood is sufficient when the joists are on 16 in. (40.6 cm) centers. Over that, you would install a cement based backerboard, 1/4" (6.4 mm) thick.

You do not want to use MDF on your subfloor, as it will swell when it gets wet. Swollen subfloor or underlayment is death to tile.

We'll worry about grout later. Cutting large circular holes will require a diamond tipped hole saw. You can get those on-line, or through better tile and masonary supply houses.

03-14-2005, 03:09 PM
I am curious as to why replacing a central heating system requires replacing some of the floor in an upstairs bathroom. What's the connection?

03-14-2005, 03:09 PM
At last! I had to go all the way to U.S.A for somebody to agree my plans are possible. Madness maybe, feasible?..........I am told the beams are 400 centres, or similar, if that helps. I don't have the distances exacltly, but the bathroom is approx 6ft, by 14ft. I am unsure how much of the beams are unsupported, but if it's anything like my old house, not much was unsupported.

Cement based backboard? What is this Bob? Is there a product/trade name?

Also, you mention MDF would swell when wet! Please don't think I'm insane, but I don't anticipate it getting wet???? Surely the tiles and grout will prevent any under material becoming wet??? Please explain.

Cheers Bob

03-14-2005, 04:12 PM
We will need some good information on those joists. Find out were the joists are resting on a wall or beam, and measure between those supports.

Backerboard in the US goes by a number of tradenames: Hardibacker, wonderboard are a couple.

Glazed tiles are waterproof, but grout is not. Nobody anticipates their subfloor getting wet but tilesetters.

03-15-2005, 12:39 AM
Thanks for the advice!
As I said, I had to go accross the Atlantic to find the solution. I will post back in a few days when I know those distances.

Cheers again

03-16-2005, 09:16 AM
Welcome, Northwest. Give us a first name, wouldja? :)

And tell all your friends that not only is it possible to install ceramic tile on wood-framed floors, it's common as dirt. The structure does need to be properly built, but this is in no way a novel idea you're pursuing here. Tell them to come visit our forums for some good tile-setting advice, eh?