Advice on lower ground solid floor

[james9570]

I have recently purchased a ground and lower ground flat in a converted house c1870. Ideally, I would like to put down laminate flooring, but I am concerned about moisture. Is this generally an issue with flooring from this era?

I have attached some photos of tracking works incase this is helpful!

Any advice is greatly appreciated!

 

[Itchinfilth]

In my experience only when its under external ground level or been covered in inappropriate materials. Is the blue coloured covering a layer on top of concrete as that won't help.

 

[Cubist]

Your property pre-dates the introduction of DPMs so it's likely that any solid ground level floors would have been constructed directly over the soil. There is therefore a high probability that damp will be rising through the floors surface to dissipate to atmosphere. Any effort to block this could result in that damp being pushed into the surrounding walls to create problems/challenges there. The blue material you have exposed is not a later addition DPM I would argue as it seems to me to be a paint of some kind - albeit that it could be/have been a liquid coating aimed at reducing damp penetration. As a consequence I would be nervous about laminate flooring but hopefully others here can offer some positive advice and suggestions.

 

[Stevers]

'Damp' meters are intended for wood not masonry, so are not much help in this instance. It's an old damp wally trick to use one that only 'works' when it suits them.

In an old house (without a DPM) solid floors need to breath, and in the heat and humidity of high summer, those lovely cool flagstones will be inclined to 'sweat'. Ours are currently doing this, manifested as darker patches usually around joints, but never actual water.

[Edit] This is not condensation as on windows, it's because the moisture always coming up through the floor is less able to evaporate. It would fail the clingfilm test for condensation but is still related to dewpoints and relative humidity.

 

[jamest]

The standard modern approach to these situations is to tank the floors and walls with some kind of membrane. This hides everything beneath and keeps the room dry and it will probably remain so for many years assuming a good standard of workmanship. It 'solves' your damp floor issue allowing installation of your preferred flooring and hides any moisture that migrates up the walls as per Cubist's comment.

No one on this forum would advocate such a program of works in your situation!

The preferred method is to somehow allow any moisture that migrates through the concrete to evaporate away and so not end up in the walls. To achieve this you could use some sort of breathable floor covering (like tiles fixed with lime grout so moisture can evaporate through the joints, a version of Stevers' case ). If you're wedded to laminate or wood flooring, then I know of only one way you can do it in your situation and that is to use a membrane like the Newton 601 slimline membrane on top of the concrete, beneath the underlay. This kind of membrane is a rigid plastic sheet with channels in it that allow evaporation from the subfloor and for vapour to escape at the edges of the floor (you have to ensure that this is possible by not sealing the skirting or whatever). The membrane was originally developed to allow the installation of floor coverings like laminate or wood over slabs that had not cured to save time.

I've used this technique on ground floor, solid concrete floors with no dpm and it seems to work OK. Of course, there may be other solutions, but this is the only one I've found that is relatively inexpensive, not disruptive and seems to work.