Thin floor screed ?

[brk1]

Following on from my soft red brick post, when "Bill and Ben" the cowboy men, built the bathroom extension on the back of my house they only managed to get that floor about 40 mm higher than the original kitchen floor on the same house level. I expect they built the extension on the back of the house before knocking through the new doorway and managed to get the new floor level totally wrong. It wasn't until I bought floor tiles to go right the way through that I found this out, I put my 6ft level on the floor and thought it must be broken, unfortunately the level worked just fine.

They built the old WC and lean to store into the extension then cocked it up as they went along. Between the bathroom wall and the kitchen wall the floor falls over 1" in just a meter, I've remedied this will deep fill self levelling mix, but now need to get the kitchen floor up level with the rest of the house, so basically I need a screed that is only about 32 mm where it joins the lobby, to about 45 mm at the far end of the kitchen, floor size works out to an equivalent 2.4 m x 2.4 m .

What's the best I can do with it, I've read about putting down a neat cement/pva primer/slurry down on the floor to hold it down, I've got fibre strands to keep it together when its down, I've also got some Ardex to get it dry quickly as there's 4 of us living in the house with the bathroom at the end of the kitchen downstairs.

Any advice, mix ratios etc would be very handy , basically the room will be 8ft square with kitchen units fixed down both sides so the whole screed will basically be held down and not floating, the 45mm depth I'm not too concerned with, its the 32mm depth in the kitchen/lobby doorway that worries me, It will be floor tiled right over but I don't want all the tiles breaking at this point or the grout joints keep cracking, the best I might possibly be able to do is to gun up a bit of the floor at this point to make it deeper if need be. Going to be well expensive if I have to level compound the whole of the floor.

Open to all suggestions possible, please

 

[1john]

Wickes sell a self leveler that will work for depths of 5mm to 50mm if I remember correctly.

I have in the past put a coat of SBR down and then a sand and cement screed in a situation not too dissimilar to your own although it's not reccomended, this was for myself, i was aware of the risks and was/am prepared to redo it if it fails.

 

[brk1]

Thanks 1john, I actually used that deep fill leveller to do the lobby, it would cost me an arm and a leg to do the whole floor in it though , when I patched up my lobby floor to get that level with the bathroom, that was 1" to nothing out and was only 1m x 2.1m in size, so basically it formed a long 1" wedge on top of the floor, that took 2 bags and still wasn't quite enough, at about £11.50 a bag if you buy 4 or moreI reckon I'd need about 15 bags to do the kitchen floor If I was lucky that's why I'm trying to find a cheaper alternative if possible,I suppose it could be bulked up with sharp sand to save a bit like latex self levellers can be. I know they make Ronafix which is supposed to be a bit stronger than SBR if that would help hold it down better, if the thin bit was under the kitchen units totally I wouldn't have minded but its smack bang in the centre of the doorway, there will be a 1m strip right down the centre of the kitchen basically with the units either side of it.

Would a slightly harder screed mix with fibres in it give me a better chance of it staying together as one total screed layer. It's also in my own house so could be repaired/re-done but that would mean I'd have to renew all the floor tiles as well if it happened ,I've got enough spares to do the job comfortably but can't get any more of them anymore.

 

[1john]

What are you concerned about happening?

When I did the floor i mentioned I used nothing but an SBR coat to prime the sub floor, sand and cement over top, like you it was tiled over. I cant say you wont have a problem, it will be fine ect ect as if it wasnt or didnt work out i'd feel very bad about it, the floor I did has been tiled about a year now, no loose tiles, no cracking grout, no cracked tiles, no hollows when tapped.

 

[1john]

BTW, when this gets pulled up in X amount of years, you'll be the new "bill and ben cowboy men" someone else is ranting about

 

[brk1]

I don't like doing anything Bill and Ben style ,I hate to see it being done by anybody, I believe in doing a job properly, then it only needs to be done once,my main concern is it cracking right in that lobby doorway, that original floor may have been there 100 years or more and may suffer from movement ,It might not do, I didn't want the tiles to snap in line with the doorway where the screed would join the other floor or the grout to keep cracking. In my searches for answers I came across a screeding site that gives lots of basic info, they state that you can go as thin as 10mm with a chemically bonded screed on a bonded floor,, my 30mm should be ample, but they give no mix ratios etc to help out. Here's a link ,sorry if it's classed as free advertising for somebody, please remove it if I've done wrong,,it's a F.A.Q

http://www.adhf.co.uk/html/body_screed_faq.html

Just looking for some mix ratios and helpful pointers as to strength of screed for best results, I've got the basic ideas needed, just any better advice from pro's would be very helpfull