300 Year Old Cottage Concrete Floor / Flooring

Hi there,

I live in a (roughly) 300 year old cottage in Wales which had an extension added by previous owners.

What looks like a new concrete slab, heavy underlay and carpet was in the lounge (old cottage) and the walls were plastered and painted, covering the lime render and original stone walls.

I’ve taken the plaster and old render off exposing the old walls as they couldn’t breathe. I wasn’t going to take the lime render off as it was none dry, but it was already off in places so it all ties in.

What is the best thing to do regarding flooring and insulation on the cold concrete floor? They couldn’t breathe before and the underlay was damp with condensation. The slab itself is dry.

There is also a gap between the slab, and then the old walls - is this intentional? No DPC in the old cottage due to age. Any advice would be greatly appreciated.

from your pics it appears that the stone walls are simply built off the soil? is that right?
i dont see any membrane (DPM) in the gap - so it seems that the slab was also simply poured on to the soil? does that seem right?
i have seen intentional narrow gaps before, and channels that have been cut at the slab-wall junction but i've never seen such a wide gap - how wide and deep is it?
you mention underlay - underlay under what kind of flooring?

are you on a hillside?
can you post a pic of the outside wall surface at ground level?
how long have you lived there?

Hi thanks for the reply and sorry for the delay!

Behind that wall is the new extension so I’m not really sure what to do. I planned on putting a new wood floor down now that the slab can breathe but I’m not quite sure how to go from here!

Not on a hillside and behind that is my kitchen and floor which is at roughly the same level.

Cheers

Joe

Are you certain there is no insulation under the concrete? If it’s relatively modern there should be.
If it had been insulated there should have been an upstand at the edge - where your gap is.
Is the gap as deep as the slab? Can you feel under the slab?

You can test the slab for moisture with a protometer or hydrometer, don't rely on the DIY moisture meters used for wall's as they will give a false reading.

if there is moisture present in the slab, apply a Liquid DPM and a Moisture tolerant Self Levelling Screed like Arditex Ardit Na before approaching the floor installation (Floating engineered on a foil backed firm underlay probably the best option under the circumstances)