leveling floors for carpet

[Paul]

Having a new carpet fitted in lounge. lounge was knocked through in the past, there is about 10mm difference between floors which are concrete. previous owner just filled in where dividing wall was at a slope that you can feel as you walk on it. as stated both floors are concrete and both have old vinyl floor tiles stuck on them which I want to leave if possible. what would be the best way to make the levels less noticeable. one way I have thought about is to use layers of different width hardboard to spread the slope over a wider area. any other suggestions?

[Grunff]

Your hardboard idea won't work, because in order for it to spread the slope over a larger area you'd need the hardboard to be in close contact with the concrete at one end, then to be separated from the concrete by an air gap. You'd need to fill this gap with something to avoid the floor bouncing as you walk on it.

The only real solution is to bring the whole floor up to the same level. There are lots of ways of doing this for a 10mm level difference. You could use a runny concrete slurry as a thick self leveling compound (most self leveling compounds can only be used up to around 3-4mm thick, which is why you have to make your own slurry). Alternatively you could screw down some 10mm ply (not common, but it is available).

[Paul]

The idea I had was to have say a 3ft wide piece of hard board then ontop of that a 2ft wide and the ontop of that a 1ft width then sand down the steps so they are less noticeable, so the gradient is spread over a 3ft area.

[Grunff]

Ok, I see what you mean, but I still don't think it would provide a satisfactory solution - doing with with concrete would be easier, cheaper and quicker (not counting setting time).

We did this in one of the rooms in our last house. Just mixed up a slurry using cement and fine sand (1:4), using PVA in the gauging water (around 1:4 PVA:water). Worked great.

[Stuart Noble]

Agreed. I'd make it a thickish mixture and level it with a length of wood. Can't really go wrong

[Lobster]

I've done it myself along the lines of what the OP is proposing. In my case, the "low" room had a door at eithe end so raising the whole floor level was not an option as it would just have transferred the problem to the next doorway.

My 'step' was about 12mm IIRC, and I made a shallow ramp out of concrete going into the 'low' room. It was a case of tapering off the concrete as much as possible. On the second attemnpt I treated the original surface with dilute PVA (after the first attempt failed as it all broke away when set!).

It worked fairly well - you can just tell you're walking on a gradient, but nothing like as much as if the slope were just across the thickness of the wall.

I'd certainly do a 'Grunff' in preference unless there's good reason not to.

David

[Paul]

Thanks for the replies, I think I'll try the concrete method. the only problem I have now is removing a few rows of the vinyl floor tiles that are covering the concrete floor. I think I'll get a wallpaper stripping knife out the attic tomorrow and see how well stuck down they are.

[Stuart Noble]

With enough pva in the mix it may bond ok to the tiles. The "general purpose" mortar from B&Q seems to have the right balance of sand particle sizes. Ordinary sharp sand may be a bit too gritty

[The Medway Handyman]

Blowlamp or hot air gun makes them much easier to shift - does pong a bit though.