Damp concrete floor

[rimfire4969]

After a bit of advice:

Our house is having some new carpet, lifting the old one which has been down about 9 years we have a damp area. The underlay has broken down and the carpet grippers rotted to powder. This part of the house dates back to about 1750 and it is only part of a large room 7 metres x 5 metres that has the issue. I have googled and found various things but first hand advise is usually better than google. Is there a paint maybe resin based they I can put on the floor to act as a damp barrier. I am not going to dig up the floor and relay it. 

Any help much appreciated. 

[Raja Clavata]

First things first, can you rule out the possibility of any pipe work running through the concrete?

That being the case and if you don’t want to spend time with a dehumidifier then maybe a vapour barrier sheet is your best bet?

[millrace]

If not a pipe..then dont waste time

Liquid dpm.....its a 2 part epoxy mix ,,  apply with 3mm serrated trowel let harded no more damp....simple

[bruno22rf]

Swimming pool paint?

[JohnfromUK]

I have a part of the house (part of the hall) where there is a flagstone floor (circa 1840).  It regularly suffers from damp and I have had it investigated as it is a nuisance rather than a problem.  The conclusions were interesting.

• It is not water from a pipe (there are none).
• It is not 'rising' damp because it is on an area where there are cellars under (The floor part is rather over a foot thick) - and is an impervious stone (slate like).
• It is caused by condensation.  The 'problem' is simply that it is a very large 'thermal mass' and is often cooler than the surrounding air.  On warm humid days in spring it can get reall quite wet.

Various solutions have been tried with various paint/compounds before it was fully investigated - all with little effect.  There is no simple answer, the easiest solution being to leave it as stone flags and try to control the humidity by ventilating on dry days.  I have do doubt that years ago when there were 8 open fireplaces in the house (all used) and draughts that came high up the Beaufort scale - it wasn't really a problem.  Now days with a house largely draught proofed and insulated, and central heating rather than open fires, it can be a nuisance ........ but there is no cheap practical solution that I know of.  Various solutions were proposed which involved re- flooring, an insulated skin, heated underneath etc are all impractically expensive (not least because that part of the floor braces various walls and is in effect structural.

Could yours be condensation on a part of the floor that is cold?

If it  is from below - and you 'seal it in' - it may reappear elsewhere.

 

Edited October 25, 2019 by JohnfromUK

[oowee]

I had a similar situation in a concrete floor in an inter war house. The floor was core tested to look at the type of concrete laid to see if it was some sort of problem concrete (I can remember what they were looking for). Then camera down drains which were found ti be blocked. All floor was lifted throughout the house and all plaster hacked off for a metre in height. Redecorate and new carpets throughout. New drains were installed.

Nightmare and a month in a hotel. 

[figgy]

I'd lift the concrete floor and replace it with sub floor and damp proof membrane with new modern concrete 

Decent builder could have it done in couple of days.

Edited October 25, 2019 by figgy

[rimfire4969]

No pipes near this part of the house. The old carpet has been down for 9 or 10 years so it’s not a major problem.

I know replacing the floor would solve the problem but that ain’t happening. 

The 2 part epoxy seems to be the easiest way to help and for £100 I can do all I need. 

[mowdy]

wooden pegs used for leveling the concrete back in the day and left in .which have rotted and allowing damp to travel through concrete or a damaged/no  membrane  both are common faults with damp floors.

[vampire]

4 hours ago, rimfire4969 said:

No pipes near this part of the house. The old carpet has been down for 9 or 10 years so it’s not a major problem.

I know replacing the floor would solve the problem but that ain’t happening. 

The 2 part epoxy seems to be the easiest way to help and for £100 I can do all I need. 

2 part epoxy is easy to put down anyone could do it and it works.

Had a contract where i used this method, after redoing the drains,doing crack repair and re render,damp injection,replaster 1 m up,high build floor leveller and then 2 part epoxy which was the easiest bit.

[Jaymo]

Any brand names

Facing exactly the same on a fifty year old house.

Laying UFH And in order to do so, had to remove the 20mm thick bitumen later which acted as the DPM

 

[Ultrastu]

2 part epoxy resin is the answer  .imo.

Just do the whole floor and as much up the walls as is practical (up to skirting level ) as the damp will other wise track side ways to find its way out past your patch up .

[pudbas1]

On 25/10/2019 at 21:06, Jaymo said:

Any brand names

Facing exactly the same on a fifty year old house.

Laying UFH And in order to do so, had to remove the 20mm thick bitumen later which acted as the DPM

 

ardtex  dpm either 1coat or 1coat rapid, f ball stopgap F78 2coat 

[Jaymo]

3 hours ago, pudbas1 said:

ardtex  dpm either 1coat or 1coat rapid, f ball stopgap F78 2coat 

Cheers

will investigate

[Vince Green]

I know of a shop that was in what had once been a  much older house, they had damp floors and it turned out there was an old abandoned cellar that had filled with water. You have to be careful with floors in Cornwall as you probably well know.