Damp concrete floor

Appleyard123

I have just bought my first house. It is an old 1850’s cottage.

On the survey the surveyor said that the property had some damp rising through the floor which ‘may’ be caused by concrete being put straight onto slabs and therefore the damp is rising through the floor. However he did not really fully know and recommended a damp proof report. The skirting boards in the room are also rotting.

The property does not have a damp proof course and in the room where the concrete floor is damp, the garden has a higher ground level.

We have had 2 separate damp proof specialists round and neither have pointed out the issue with the floor and think it could be caused by the lack of damp proof course and the higher ground level.

We are in the process of getting a damp proof course done and digging out the garden.

I would just like to know what people opinions are in digging out concrete floors and putting a membrane down and whether you think it is necessary or if there is anyway of knowing if it is needed??

societys_child

We are in the process of getting a damp proof course done and digging out the garden

That should help to some extent.

I was in a similar position, old house (age unknown), damp concrete kitchen floor. Its a long time ago.
Never considered digging it up, time, lack of funds, etc.

I put a damp proof membrane over the concrete and up the walls a few inches, laid sheets of 6' x 3' half inch thick polystyrene on that and then 8' x 2' three quarter inch T&G flooring over that. They didn't need to be fixed, simply slotted together

"Floating floor" quick cheap and easy, and not only cured the damp problem, but insulated the cold floor, and made the kitchen much warmer. . . there was no central heating.

G_M

A concrete floor will always be cold unless covered by.... something insulated/warm, and if doing that then a damp proof membrane is an obvious thing to put down first.

Digging up the concrete seems like an extreme measure.

The DPC and lower external measure should hlp and may solve the problem.

My 1851 hhouse has a slate dpc, but has suspeended wooden floors - I can lift a floorboard and see the slate slotted in between the supporting stone pillars and wwooden joists. Tht doesn't help you though. (don't know why I mentioned it. Stop rambling now.........)

Mickygg

I had damp through my old concrete floor. I tried a concrete sealer painted over thick but it did absolutely nothing.
This house too had much higher ground level on one side.
My survey said it was probably condensation due to thick underlay but it wasn't. I replaced it all but still I had the damp, smell, mould.
I don't have the house anymore but wish I had thought of society child's plan.

konark

If you want to do the job right dig up the concrete and relay with a dpc, and maybe also insulation.

If the concrete is sound, level and very solid you can use the plastic sheet dpc method or paint a dpc 3 coats on the concrete- Wickes sell it, liquid dpc it's called. Then the floor-covering of your chouce.

Was the skirting rotten all the way round or just along the wall adjacent to the high garden?

Davesnave

If it's just one room affected, then you may think it worth digging out and laying a new floor, but be warned that if you go deep to get a layer of insulation in, there will be a fair amount of removal and the disposal cost of that will need factoring-in. Skips are expensive.

As you can see, there's a good range of options, so which you choose depends on the way you view the house long-term against costs, your own capabilities and how much disruption you can cope with. Lowering the raised ground outside and adding a DPC to the walls is a good start anyway.

AnotherJoe

I would certainly wait a year or so, or at least a winter, with it as it is now once the DPC and garden works have been done.

If that doesn't do the job then if you have the ceiling height, something like SC"s solution would be less disruptive, it may be its not so much rising damp but condensation caused by a cold floor. If the ceilings are low you'd probably have no choice but to dig out.

Niv

Appleyard123 wrote: »

I have just bought my first house. It is an old 1850’s cottage.

On the survey the surveyor said that the property had some damp rising through the floor which ‘may’ be caused by concrete being put straight onto slabs and therefore the damp is rising through the floor. However he did not really fully know and recommended a damp proof report. The skirting boards in the room are also rotting.

The property does not have a damp proof course and in the room where the concrete floor is damp, the garden has a higher ground level.

We have had 2 separate damp proof specialists round and neither have pointed out the issue with the floor and think it could be caused by the lack of damp proof course and the higher ground level.

We are in the process of getting a damp proof course done and digging out the garden.

I would just like to know what people opinions are in digging out concrete floors and putting a membrane down and whether you think it is necessary or if there is anyway of knowing if it is needed??

I hope your walls are not cob!

Mutton_Geoff

Be careful digging the entire floor out, you will need test holes first since most old houses didn’t have foundations so you’ll end up removing the very thing that’s holding the house up.

AlexMac

I'm with Joe; wait a bit and see:

AnotherJoe wrote: »

I would certainly wait a year or so, or at least a winter, with it as it is now once the DPC and garden works have been done.

If that doesn't do the job then if you have the ceiling height, something like SC"s solution would be less disruptive, it may be its not so much rising damp but condensation caused by a cold floor. If the ceilings are low you'd probably have no choice but to dig out.

In fact I'm even more minimalist; if its been the way it is for over 150 years, and doesn't seem excessively damp, it could be that simply heating and ventilating it will maintain the balance which was built into it, in the days before DPCs, injected chemicals, membranes, etc were ever though of...

(...or come to that, sewers, indoor toilets and running water? Maybe my primitive approach isn't entirely consistent with 21st Century living!)