Hi everyone.

I am planning to re tile my kitchen floor and walls. Walls not a prob but need some help with the floor. Firstly I should say the tiles we will choose will not be expensive because in a couple of years time we will be knocking through and extending this part of the house, however, at the moment the tiles are coming away from the walls and the floor tiles are cracking all over the show and the whole thing looks awful.

Half of the kitchen floor is floor board and half is concrete. Whoever tiled previously has only dot and dabbed the tiles and has done so directly over the floor boards hence the cracking I guess. I'm hoping these should come up fairly easy without too much damage to the boards. The concrete half sounds as if they are more solidly fixed although there are some hollow spots.

My question is what would the best way be to prepare a floor consisting of floor boards and concrete. Hopefully if the levels between the two are not too bad I was hoping that I could fix cement board down if this was possible. If not could I ply the whole lot out using screws and plugs in the concrete. I dont want too much of a height difference because the threshold of the back door is quite low.

Thanks for your help.

Ernie

You could also try using Ditra matting

using something like hardiebacker might be expensive if you are planning to build an extension and could damage the floor shortly,not sure it would be that easy to srew the ply into concrete as it has to be screwed at about 150mm centres which means a lot of plugs and screw to match up!
you could try using a masonary screw or ring nail on a small section and testing how much movement it has?

Thanks forthe answers guys. Gazzatile are you saying I could use Ditra straight over the boards and concrete and tile directly onto these?

Dave, I dont mind spending the money now, I dont think the extention will be done for a couple of years so while the "tart up" job is down I would like it to be done properly.

Not sure if I can use cement board or not though ? would apprfeciate your further advices on this.

As an aside some of the tilese were coming away from the inside of a reveal where the back door is so I took them down. probably about 10 - 15 tiles in a column. The tilese used were 4inch square ceramice which had been spot fixed, (no serrations on the adhesive). AT least I think it was addy though it could have been grout! I say this cos the "addy" is firmly bonded to the tile but has come away from the plaster as clean as a whistle not even any scraping required. Any thoughts on this out of interest. The tiles on the wall seem a lot more solidly fixed.

I look forward to your advice re the floor prep.

THanks Ernie

Ernie

Yes you can use straight onto floor boards, they have to be screwed to the joists to minimise movement and tile with a flexible adhesive. They have got there own website that you could look at Schlüter-Systems UK Homepage +44 (0) 1530 813396 - Schlüter-Systems hope this helps. Spotted tiles will tend to come off easier as there is less surface contact.

You can not bridge two differents substrates with Ditra without a movement joint. Also the ditra will not combat deflection in a timber floor, it must be adequately braced first.

Thanks guys, you seem to be erring towards ditra, however personally I would like to try to use either a backer board, (to limit the height diff) or if not then 15 mm ply. would either of these be suitable to bridge two different substrates. Apologies if this is a dumb question!


Thanks Ernie

Originally Posted by ern

Thanks guys, you seem to be erring towards ditra, however personally I would like to try to use either a backer board, (to limit the height diff) or if not then 15 mm ply. would either of these be suitable to bridge two different substrates. Apologies if this is a dumb question!


Thanks Ernie

Not really practical to "bridge" the 2 substrates. They will have different expansion/contraction rates, which is why you need the movement joint.

Thanks for the reply Grumpy. I have never dealt with a movement joint but I am assuming the following.

For arguments sake lets say I use Hardie board, I lay this over the concrete part up to the floor boards, lay the movement joint over the point where the different substrates meet then continue with cement board in the rest of the room then tile as normal but the movement joint is actually a grout line when the whole thing is finished. Also i'm assuming the movement joint gets laid in the addy?

Any pointers would be appreciated.

Also, would it be ok to lay cement board over a concrete floor just to eliminate the use of an SLC, (where the would be a difference between cement board on floor boards - if u see what I mean?)

Alternatively, assuming the floor boards are solid can I use a ditra over the two substrates incorporating the movement joint ?

THanks - Ernie

I salute you for making sure your floor is correctly installed, but it does seem to me like a lot of extra cost for a floor that will ultimately be ripped up not to far from now. If both substrates are soild and sound I would be very surprised if the building would move at all between now and when you have your extension done. I would just install hardi and use a flexible adhesive. How old is the house? and when are you going to extend.

Hi Colour republic thanks for your comments. The house is 1930's built, the extention in the kitchen was done I think mid 80s and as for our extention Im hoping 2 years but in the current climate maybe more.

Im kinda hoping that given the above your idea might be ok.

Ta Ernie

Your house and extension has settled by now, the two methods of building between the 30's and 80's are not too different. although I can not say that with too much conviction without seeing it. Many different factors need to be taken into account, type of construction, detatched, semi-detatched, terraced, foundations, type of soil it sits on, are you on a flood plane, the list goes on....

But as a general rule of thumb if you can not see any signs of movement in the plaster or brick work (hairline cracks) playing perticular attention to the area where old meets new then any major movement has already happened and any further movement in the next 3-4 years is going to be minimal. Personally I would take the risk and spend the money for having a top notch tiling job done when the extension is built.

One last thing before you make your choice, you say the tiles are cracking all over the place, are the cracks localised to each tile or can you see where the crack travels to the next? i.e does it travel from one wall to another cracking all tiles in it's path?

Hi colour republic. The tiles are cracking locally, there is no continuous crack along the floor. These have been fixed without a solid bed and it looks like impact marks where pressure has been exerted on the hollow spot underneath. Many thanks for your comments but one last thing can I fix cement board to the cement floor with adhesive (flexible im assuming) without the need for screws or would it still have to be screwed at 150 - 200 centers ?

THanks - Ernie