Hi again,

I have prepared by 600mmx600mm polished porcelain tiles and have screwed down 18mm ply onto the old chipboard to reinforce it.

Thing is the old chipboard wasn't that level, now that I have the tiles ready I can lay them out to see the scale of the problem. I have attached pics.

Short of it is that I thought that the odd mill I could cope with but am not sure. I have only 12 tiles to lay and 9 of these will be fine. However three I can see will have problems with (they will rock if you know what I mean).

From what you can see what would you recommend? Self levelling compund? If so which one?

The adhesive will cope with that but if you wanted to use SLC then Mapei Fiberplan is the one to use.

I was concerned about the rocking. Can I push the tiles down on one side to get them level and expect it to hold position?

btw was born and raised in Kingswinford and went to college in Stourbridge!

As long as the tiles have a good bed of adhesive you will be fine.

I was a Wordsley lad and i didnt go to college

I agree with Siramic ,introducing another material in to play, like a slc brings other issues to the table. Best use a stiffer mix & rely on the adhesive to do the job, dealing with less variables then,especially, if you only have a few problem tiles

Originally Posted by Tecnik2000

I agree with Siramic ,introducing another material in to play, like a slc brings other issues to the table. Best use a stiffer mix & rely on the adhesive to do the job, dealing with less variables then,especially, if you only have a few problem tiles

Don't mix cement adhesives to a stiff mix. Always mix as per the manufacturers guidelines, if you have to bed the tiles up a little to get them flat then thats the way to go.

Spot on advice about mixing, is the problem area the high point or low point of the floor, I can't really tell from the pics, if it's the highest point then obviously all the other tiles are going to have to be packed to bring the floor level, too much addy that way, so a slc would be my choice, fibreplan as mentioned, if they're are at a low spot and only 3 tiles to be built up then go for this method.

EDIT, looking at the pictures again, a larger notch trowel might be a better option as the difference doesn't look that great, maybe a 15mm, hard to tell exactly.

Steady guys, I only said a bit stiffer . to avoid too much slump on bedding up

you could screw and glue 6mm cement sheet down first then tile should give a better surface if height isnt an issue

Height's a bit of an issue.

The problem is that the chipboard (now covered with ply) is a bit if a bowl shape but only along one edge. So two corners of the floor (adjacent) slope slightly upwards.

I have a thick bed trowel (I am a diyer) which is semi-circular shaped and I think 20mm at the peak.

If I need to back butter the tiles to get them to sit level I guess that I have to make notes on which ones will need this before I put anything down because of the surface adhesion will make them difficult to get back up if I bed them down to see if any back buttering is needed.

It would be a good idea to back-butter them anyway. Large tiles and un flat floor, mix the adhesive to the directions on the bag, spead the mixed adhesive onto the floor using your thick bed trowel. Then use the back of the trowel to skim the back of each tile with adhesive and twist each tile into the adhesive on the floor. It is very important that you get as much of a full bed under the tiles as possible. Looking at the pics I think this all you need to do, I think SLC is a over kill for this one.