Laying new concrete foundation

Ximian

My parents live in a bungalow and we have noticed that over the past few years the floor is sinking in the middle of the room (judging by the skirting boards) and cupboards lean angle. My parents have been talking about levelling the floor but they are concerned that the existing floor should be dug up and replaced with a new concrete. We were wondering if this is something we could do ourselves and if the flooring needs to have some waterproof membrane laid down first. What is best way to tackle this type of problem and what material is suitable?

TIA

ormus

what is the current construction?

Ximian

ormus wrote: »

what is the current construction?

The flooring is concrete. The floor we're concerned about is carpeted so we're not sure what condition it really is in until we pull up the carpet but from the hallway that was levelled last year the floor is concrete throughout the house, built circa 1950

ormus

then it may just need a new screeding. not too expensive.

or even just some self leveling compound putting down?

Ximian

I think the difference in floor level is too much for self levelling compound, it appears to be an inch or even more difference in the middle of the room compared to the edges/corners of the room. We're worried that if we just level the surface, that the fix will be temporary and might sink again in a few years time.
Is screeding something we can do ourselves? Do we need to use any type of membrane?

ormus

http://www.diydoctor.org.uk/projects/floorscreeding.htm

its a fairly simple diy project. but its one of those jobs where i usually get someone in.
its not that expensive and they do a far better job than me.

Kiran

You need to find out what is causing the floor to sag this much. Is it definitely concrete and not timber?

If it is concrete and the level difference is approx 25mm as you have indicated then you can still use a leveling compound such as this http://www.wickes.co.uk/Deep-Base-Levelling-Compound/invt/154050

The advantage to these is that they go off much faster than a traditional sand cement screed.

HTH

Ximian

Kiran wrote: »

You need to find out what is causing the floor to sag this much. Is it definitely concrete and not timber?

If it is concrete and the level difference is approx 25mm as you have indicated then you can still use a leveling compound such as this http://www.wickes.co.uk/Deep-Base-Levelling-Compound/invt/154050

The advantage to these is that they go off much faster than a traditional sand cement screed.

HTH

The floor is definitely concrete. Thanks for the Wickes link. I'm hoping to clear the room sometime soon and pull the carpet up to see what's going on underneath. I'm hoping that it isn't anything serious

iamcornholio

If the floor slab is sinking, then it's sinking for a reason and its no good either re-screeding or replacing the concrete in isolation.

Poor or uncompacted fill, a drain or mains leak, or poor construction are typical causes, but there are others possibilities.

You need to get the problem diagnosed first, before you even consider any type of repair

ukmaggie45

Built in 1950 I would want to check for sulfate (alternative spelling sulphate) attack. Also known as concrete sickness. I most definitely agree with iamcornholio that it's necessary to find out what the problem is. If the hallway has already been re-levelled, what was said about the original floor there? (if anything)

Here's a link for a Google search.

Hope I'm wrong, but you should maybe at least check it out.

Best wishes for an easy resolution!

iamcornholio

Sulphate attack typically causes the slab to rise and crack, not sink