Advice please on floor

[yodaboda]

I got a builder in to knock through an internal wall and level up the resulting new room so that it could be tiled throughout the new room is approx 30 sq meters. The existing floor had a step down so it had to be levelled up. The lower level was cement and the higher level was floorboards. Cement was poured onto polysterene to bring it 12mm higher than the floorboards then 12mm marine ply was screwed to the floorboards. The problem is the floor is not level. The builder says its not level due to the floorboards not being level. The hearth where the chimney breast used to sit is also causing it not to be level. The builder now says I should get some leveling compound to level it up. I have also noticed that the floor seems to move up and down when I step on it especially where the plywood meets the cement.

Does anyone have any suggestions as to how I can go about fixing these problems, the unlevel floor and the bouncing floor? Will a tiler be able to level it out when he is tiling and is there anthing else that can be done to fix the plywood from moving, Can anyone also tell me if the buildder has done the job correctly or are the problems ocuring because he hasn't done things correctly thanks

i have reposted this question as think that i didnt give enough info when i posted it earlier this week hope it makes more sense and someone is able to advise thanks for any advise anyone is able to offer

 

[Tozzy]

A difficult post to advise without pics.

Cement was poured

Is this a sand and cement screed? If so, what depth? Does it it have a suitable base? My base uses 1.5" sharp sand (compacted), 4" cement and aggregrate and I will lay a 3" sand and cement screed ontop followed by a 0.25" layer of self levelling compound if necessary.

Check your base and let use know how it compares with mine.

Cement was poured onto polysterene to bring it 12mm higher than the floorboards then 12mm marine ply was screwed to the floorboards.

Why did the cement have to rise 12mm higher than the floorbaords?

I have also noticed that the floor seems to move up and down when I step on it especially where the plywood meets the cement.

If you observe carefully, you should be able to trace the source of this problem. Maybe it is not fixed down securely. Sounds like the ply has warped causing it to undulate.

The problem is the floor is not level.

You mean the floorboards slope? It's never a good idea to work with bad work. Any new work will be affected. It's probably best to work on getting the floorboards level (straight) first. This must be a issue with the way they were laid on the sleeper walls.

I know my post isn't much help. Just thought I'd try and see if it could help a little.

 

[noseall]

what the builder should have done is lay the concrete floor level with the floor boards then covered both floors in ply, bridging the vulnerable wood-concrete join as he did so.