Best way to resolve damp kitchen floor

[Sprocker]

Hi all
I've lifted my 30year old vinyl tiles on my kitchen floor as we're replacing the kitchen atm and noticed the floor is damp in areas, smells bit musty etc, but since the flooring has been lifted the damp areas seem to have dried up a little bit
So I'm assuming there isn't a leak but it's more the moisture in the floor couldn't evaporate?
The floor also isn't level and cracked in places so needs screeding regardless

The house is a 1930s so I'm assuming there isn't a dpm currently installed

So if anyone has any ideas to to resolve the damp that would be great
Thanks in advance

 

[blup]

It's amazing how much water can build up under lino flooring in a kitchen like this over the years from day to day use, from condensation of moisture as well as spillages of water.

Let it dry out for as long as possible, but as you say it's also possible that damp is rising if there's no dpm, or it has failed.

Blup

 

[wwwebber]

We had exactly the same in our house. Damp under old vinyl tiles. We simply put a foil backed underlay down before putting our new flooring in. Sorted.

 

[Sprocker]

Thanks
Do you think the damp would need sorting first or what's causing it?

 

[Mr Chibs]

Really it wants ripping out, there will be no damp proof membrane, so all you are doing will be covering it up.

 

[wwwebber]

Nope just put it down to being an old house. The damp lived quite happily under the old tiles and will now live quite happily under the damp proof underlay . I am not sure you really want to dig the entire floor up to solve it ?

 

[Sprocker]

Ok am i right in assuming that it shouldn't be a leak if it dries out when the floor is exposed? And that I tgs fairly common in older houses?
Thanks

 

[wwwebber]

Ours dried out quite quickly when exposed so its just natural damp coming up through the floor. And yes this is common in old houses. Found it in our current house and our previous one. We did not need to dig the floor up.

 

[Mr Chibs]

Agreed, it will dry out when exposed to air, only to return when covered up. As long as it's not bridging onto your walls, you can live with it, if there are areas where the wall has a damp patch, it may have 'bridged' the DPC and you wont be able to stop this by laying new tiles on top.

 

[Sprocker]

Thanks for the advice everyone, only reason I would consider digging up is that the floor is a little uneven and damaged and cracked where there was an extension added previously, the floor needs screeding anyways but I'm unsure if you can screed over a cracked up floor?
Thanks

 

[bobasd]

OP,given the price of houses its foolish not to spend a few bob on cracking out a kit slab, investigatin an making good.esp as its bein refurbished anyway.

you dont say what you want to put down as a finished floor?

you want to put pics of the floor on here, an photos of the the outside ground levels.
if units still in place its possible thers damp under the cabs an in the wall behind?

when dealin with floors we only take the job if we can expose the base , in your case, a conc slab.
an fix the cause of the damp.

"natural damp" comin up from below is as "happily"welcome in most houses as natural rain fallin from above.

 

[Sprocker]

The kitchen units are still in place, the floor level outside is about 8 inches below the dpc so no issues there (house is built on a hill) im planninv on putting down engineered wood as a flooring, and I don't mind the graft of ripping the old floor if needed i'm just not sure on the process of making good again, I'm a new diyer and this house is my first fix er upper I just want to do it right first time before new kitchen goes in
I'll try and get some pics soon
Thanks

 

[bobasd]

heres what we do, we pull all units an appl's an then crack out the slab.
lots of slabs look to be say 6" thick an sound an turn out to be v. shallow an skimmed over a damp earth or rubble base - no membrane.

usin the threshold of the dinin room as a benchmark - blind the dig out with sand - lay a membrane that goes 6" up the walls an then pour the slab.

we hack off the walls to at least window board height ann render back up with sand an lime an a remedial skim.
before renderin we open up a few places to check the cavity for rubble bridging.
outside render is always treated with suspicion for penetratin damp.

a hillside build means possible water table troubles.

 

[Sprocker]

Thanks for the thorough description
The house is built near the top of a hill so water table shouldn't be too much of issue, I've cut trees down in the garden and haven't got any water yet! and I Think your right house is 1930s so assuming there isn't a dpm of any type underneath, would you i insulate the floor aswell of just dpm then fill with concrete?
Thanks

 

[bobasd]

if you insulate you must dig deeper - make a section view dimensioned plan from bottom of digout to FFL.

you can use two membranes - one below the insulation an the other on top of the insulation - then pour the mix on top of the insulation.

aamoi we dont screed anymore - we pour to the required level then lay the finish flooring.

you cant do this job halfway - youve got to insulate an concrete the whole floor.