Kitchen Floor Mess

[jaseleeworth]

I am somewhat out of my depth with a house renovation and would massively appreciate some advice regarding the kitchen floor...

There has been subsidence at some point in the house and the concrete kitchen floor was uneven to the tune of around 50mm from high end to low end. I ripped off the tiles and after finding some weak spots in the concrete and pockets of hollow space underneath, for better or worse I dropped the whole concrete floor with an SDS drill.

On my father in law's advice, we removed a good deal of the hardcore and laid sand screed over the top of remaining hardcore to get a level. He assured me that we could put in a DPM after the fact and now he has returned home leaving me with a set sand screed floor (a good deal of loose screed on top), no DPM, no concrete subfloor and wondering what the f to do next!

Am I correct in thinking that this will not be structurally sound? Am I correct in thinking that any liquid DPM will only shift the damp to the sides of the room? Should I should rip out the screed and start over?

 

[BlueLoo]

I'd pay for a building engineer to advise you on the floor and the subsidence.

 

[tell80]

Please post pics of the existing kitchen floor - the whole room and some details, & where you think there was, or is, subsidence?

Besides the kitchen, where was subsidence indicated/located by who? when?
Was it a mortgage surveyor - if so, do you have a report?
Are the other rooms solid or suspended floors?

Do you mean that at present there is a layer of sand over hardcore?
Or do you mean that the screed is a layer (how thick) of sand and cement?

Do you know yet what final finish floor cover eg tiles, you will use?
Do you know where your DPC is in the walls?

 

[Nige F]

I'd pay for a building engineer to advise you on the floor and the subsidence.

You don't need that - you've got tell80

 

[^woody^]

A liquid surface DPM can be suitable if it joins with a wall DPC or laps up the wall bottom. The risk is when you have a high water table or high water ground pressure.

But the real question is not how deep is your screed, but How Deep is Your Love for your FIL?

For info, screed has little tensile strength and is not suitable as a floor.

Typically you would have

• H/C
• 25mm sand blinding
• DPM
• 100mm concrete
• 3mm self leveller or 50mm screed

Insulation would be optional above the DPM or the concrete

 

[jaseleeworth]

Thanks for replies.

To answer a few questions: Subsidence evidenced through diagonal cracks in walls which we have stitched. The house is on a hill and slopes downhill throughout each room. Honestly I can't be certain if historical or live. I am planning to monitor over the next year because the budget does not currently stretch to a structural engineer or underpinning. Final floor covering will probably be engineered wood.

The screed (sand & cement) is 50mm, but clearly we have skipped some steps. I am leaning towards going back a step and going for the sort of setup detailed by Woody. My love for FIL has both historical and live subsidence.

 

[tell80]

As you were advised above: hire a SE.
At the moment you might be wasting money, energy & time attempting things that later might have to be re-done.
You must insist that the SE will tell you whats wrong and, most important, how to fix things.
All this must be in the survey report.
Some SE's issue entirely digital reports full of useful diagrams, pics or videos.

 

[mikeey84]

FWIW I agree that hiring an SE for a survey would be the best idea.

Then at least you know what you are dealing with, and as above not wasting your time doing something that will need to be ripped out in a year or 2