Repairing hole in concrete floor - damp issues

[Artair]

Hi,

I have always had damp in one corner of my bedroom behind a bedside table. I'm redecorating the room this weekend and on lifting the laminate the concrete floor was cracked/damaged in the corner, and the laminate that from that corner was swollen, so clearly getting damp. I've pulled out the bits of broken concrete and can see the DPM which runs down the inside of the wall and presumably goes under the floor further down, but it does look like its split a little bit.

What would be the best way to fix this? Can I just put some kind of sealant on the split, then fill the hole with concrete? Or is there a better solution?

Thanks

 

[Burnerman]

Consider digging out any loose concrete / rubble whatever, allowing it to dry and then giving the hollow a thick coat of Evercryl before putting fresh concrete in? Its worked for me, but every situation is different.
John

 

[ree]

Why not post pics? Show the exposed floor patch, and the walls in the corner at skirting level. Can you also pic the outside of the wall at ground level, and show where the DPC is located?

Who laid the concrete and/or the laminate?

Carefully examine the rest of the floor and wall surfaces for signs of damp.

 

[Artair]

The concrete was laid when the bungalow was built in 1962. The laminate was put down by me approx 18 months ago, however I didn't notice the hole at that time.

Here is two images on the hole in the corner. You can just see the DPC from the inside just below the floor level, with the DPM going down the inside wall just underneath it.



Here is a photo of the outside corner. A bit of background info: when we moved in, it was solid concrete all down the side of the property and around the back, at about 1 1/2 bricks below the DPC, and rising to half a brick below at the opposite side (which was actually free of damp) but this has all been removed now (about 6 months ago). There is clearly some damp there as you can see the moss growing on the bricks. It's clay soil and tends to not drain very well.



Thanks for your help.

 

[ree]

Thanks for the pics and further info.

1. The right hand (RH) wall shows faint discolorations possibly due to damp/salt stains?

2. The membrane (DPM) looks to have possibly been cut short: it should run up the wall for about 90mm, or run up to tie into the DPC.
Can you scrape away any remaining plaster etc. to expose the membrane and DPC more clearly.
Plaster should not be in contact with the concrete.

3. Same on the other(white) wall if you removed the skirting. Use a utility knife to cut the skirting top edge loose.

4. Was the skirting that you have already removed rotted on the back?
Why not remove the other skirting and examine it for decay?

5. The exterior pic shows what was possibly some kind of remedial measure using bitumen at the DPC level - this kind of thing never works. Or perhaps its an extremely thick DPC?

6. The RWP enters straight into the ground - it may pay you to open up that area and check where the underground pipe discharges to, that its not blocked, and that its not leaking. Tests can be performed without opening up but its typically a plumbers job.

7. Do you have cavity insulation?

8. Another line of inquiry is to open up at the wall, and see if the cavity has bricklayer's rubble bridging the DPC?

9. Until the cause has been established its not worthwhile to begin remedial measures.

Simply refer to item numbers if you reply.

 

[Artair]

Thanks Ree for tying to help.

2. I have attached another two photos trying to better show the DPM. The LH (purple) wall, the DPM does come up the inside of the wall and tucks under the DPC; however on the RH (white) wall, this clearly does not, and having removed the skirting I can see the brickwork (there was also some damp clay there, too)

3. Skirting removed - see above comment

4. The skirting shown in the photos is original to the house. This was all replaced when I decorated the room 18 months ago (shortly after moving in). The reason this piece still reamins is because the radiator is on the wall, and the pipes are attached to the skirting. It was easier to box the whole lot in than attempt to remove that bit of skirting... although the boxing in part never actually happened! The bit that was already removed before I took the photo shows no sign on damp, and I have now removed the bit that remains, which also shows no sign of damp.

5. The DPC appears to be a lay of mortar, the DPC and another layer of mortar on top. The previous occupier was a lone elderly lady, and I suspect some cowboy told her she needed some work doing, as the DPC is like that all the was around the property. Its like someone has just covered the DPC with more mortar.

6. That is a gate post, not a RWP.

7. Yes

8. I'd rather not do this if I can help it.

9. Looking at the new photo, what you said at 2 appears to be the case. Should I take up more of the floor along that wall and see whats going on?



Regards

 

[ree]

Thanks for the new pics and info.

I'm glad that the skirting was clear, and given the good height above ground for the external DPC there's no pressure to open up the wall.

On external walls you could cut back all interior plaster from contact with the slab: clean off to above the DPC. It could be done in line with future decorations.

In the corner:
you could clean out the patch and make good the split.
Run a loose ripping of plastic up the wall a bit.
Fill the hole with a small bag of ready mixed S&C from any plumbing supplies.

Its your call ref. the damp affected wall plaster: it should come off for 300mm past all damp signs, and be re-plastered with a render of lime and sand. The render will give you 10 to 20 yrs of salt free surfaces. But you decide what you can live with.

Likewise the possibility of opening up at the edge of the slab - perhaps, wait and see if any moisture affects any finished floor covering?

If at any later time mould appears come bck here - you dont want to live with mould.

 

[Artair]

Hi Ree. Thanks for that.

I've broken away some more of the concrete to see how much of the DPM is cut short. Looks like its not that bad as the DPM tucks under the DPC as it should do a little further along (see new photo).

I'm not sure I follow when you say to run some plastic up the wall a bit. Surely if I run some plastic up the wall, this will allow damp to rise past the DPC?



Regards.