Concrete floor - damp proof membrane installation

jacksons

I am buying a property and a survey has shown that the solid ground floor (likely concrete slab) is damp in some parts and is also uneven. Recommendation is that the floor is re-laid with a damp proof membrane (as a DPM would not originally have been installed).
The affected rooms are a small kitchen and lounge. Have been quoted £3300+VAT to include taking up kitchen and lounge floor, re-hardcoring them, lay a damp proof membrane and insulate with a 75mm finish (includes skip hire).
I’m wondering if there is a cheaper way of doing it. For example, lay membrane over existing concrete subfloor and screed over that? Or any other alternative?
Thanks!

FreeBear

jacksons wrote: »

I am buying a property and a survey has shown that the solid ground floor (likely concrete slab) is damp in some parts and is also uneven. Recommendation is that the floor is re-laid with a damp proof membrane (as a DPM would not originally have been installed).

How old is the property and what sort of construction ?

If it is pre 1900, solid walls, and the floor is original, ripping it out and replacing with a concrete slab is probably the worst thing you could do. If it is a concrete slab in a pre 1900 building, digging it out is good as long as it is replaced with either limecrete or suspended timber floor.

A 1930s onwards property with cavity walls and concrete floor in all rooms, you could just pour a liquid DPC on and then put laminate down. It won't fix the problem - To do that, you need to look to see where the damp is coming from. Leaking gutters/downpipes, elevated soil levels outside, leaking pipes internally.

Final note - Whilst digging out a concrete floor is doable, removing sufficient material to do a "proper" job could entail digging down below the existing foundations - This is something that should be avoided.

jacksons

Many thanks for your advice
House built around 1900. Mid-terrace. Solid walls and original floor.

I have no knowledge at all about this kind of work, is taking up the existing floor finish, laying a membrane over the concrete slab, and re-screeding not viable? Appreciate this wouldn't necessarily solve the problem

The quote did not specify whether he was replacing the existing concrete slab with new concrete slab, or what material the "75mm finish" would be. So a bit vague

dunroving

jacksons wrote: »

I am buying a property and a survey has shown that the solid ground floor (likely concrete slab) is damp in some parts and is also uneven. Recommendation is that the floor is re-laid with a damp proof membrane (as a DPM would not originally have been installed).
The affected rooms are a small kitchen and lounge. Have been quoted £3300+VAT to include taking up kitchen and lounge floor, re-hardcoring them, lay a damp proof membrane and insulate with a 75mm finish (includes skip hire).
I’m wondering if there is a cheaper way of doing it. For example, lay membrane over existing concrete subfloor and screed over that? Or any other alternative?
Thanks!

You might find it helpful to scour the Flooring Forum:

https://theflooringforum.com/

- professional floorers' forum, There's a sub-forum on preparing sub-floors prior to laying flooring.I found the discussions here very helpful.

Also look for my recent thread on a similar topic, but different circumstances. Search for "DPM" in the thread title.

FreeBear

jacksons wrote: »

House built around 1900. Mid-terrace. Solid walls and original floor.

I have no knowledge at all about this kind of work, is taking up the existing floor finish, laying a membrane over the concrete slab, and re-screeding not viable? Appreciate this wouldn't necessarily solve the problem

Don't suppose the floor still has an original tiled surface ?
If so, you have something that should be conserved and not thrown out & replaced with modern materials - Cement, plastics, and other waterproof treatments will only store up trouble in later years.


I'd suggest popping over to http://www.periodproperty.co.uk/forum/viewforum.php?f=1 and see what they have to say about solid floors - Yours may be limecrete, rammed clay, or very, very early cement (would need testing to be sure).