Damp~dpc breached

never_enough

1920s house, solid walls.
Having a big clean to get rid of a moth problem (:o). Just moved the piano & a cupboard & have found a damp patch on the wall. Neither things were touching the wall so there was airflow, but where the cupboard was there was mould growing under, on the carpet, as it was sitting directly on it.
Anyway... our survey did mention a slight damp issue in two rooms, both on internal walls. He said the likelihood was that the slate dpc had broken, possibly with minor house shifting over the years. The area of damp is quite small, approx 1m x 1m. There was also a slight prob in an external corner, but that seemed to have cleared when I emptied the french drain of mud & refilled with pea shingle! So what is the best solution? Both rooms have concrete floors with chipboard & carpet over. We're planning on putting new floors in (wood or limestone if we can get the floor levels right without digging down) so don't mind mess if hacking off plaster is the way forward.
Grateful for thoughts or help.

DVardysShadow

Where does the water come from? On internal walls, I would be surprised if it were failure of a slate DPC - unless surrounding ground is above floor level. To me, this looks like condensation. Are the rooms in question used for drying washing? Is the space on the other side of the walls cold?

never_enough

DVardysShadow wrote: »

Where does the water come from? On internal walls, I would be surprised if it were failure of a slate DPC - unless surrounding ground is above floor level. To me, this looks like condensation. Are the rooms in question used for drying washing? Is the space on the other side of the walls cold?

Thanks for replying.
Don't know where the water comes from, just assumed the surveyor was correct about failure of the dpc.
I wouldn't think it's condensation as the window is open for several hours most days, there's a chimney & I never dry washing in the house. Unless it's because of the bookcase/cupboard thing that was there, but it wasn't touching the wall & it's not happened further along with another bookcase.
I've just measured the damp patch, & it's smaller than I thought, only 12" high & a metre long. The other side of the wall is hallway, but it wouldn't be colder, even in Winter, as there is a radiator opposite. There is damp on another internal wall too, but only about a foot square.
Any more ideas?

never_enough

Is it possible that the concrete floor has failed & a little water is coming up through that? But the dpc should stop it rising anywhere even then? I havn't seen the concrete in this room as it's under boards & carpet but believe it will have been covered in stuff that looks like bituman (other rooms were)

Mojisola

never_enough wrote: »

Anyway... our survey did mention a slight damp issue in two rooms, both on internal walls. He said the likelihood was that the slate dpc had broken, possibly with minor house shifting over the years.

We're in the middle of this right now. We're replacing wooden suspended floors in a 1930s house with concrete and have found damp on the internal walls. Your house is probably the same - the rooms have been concreted separately but the internal walls will still be on their own dpc. We are having the plaster stripped off, silicon injected and new waterproof plaster put on.

never_enough

Mojisola wrote: »

We're in the middle of this right now. We're replacing wooden suspended floors in a 1930s house with concrete and have found damp on the internal walls. Your house is probably the same - the rooms have been concreted separately but the internal walls will still be on their own dpc. We are having the plaster stripped off, silicon injected and new waterproof plaster put on.

Thanks for replying.
I think we're just going to have to bite the bullet & move all the furniture out, then get the boarding & carpet up to have a look. I'm going to take the skirting board off as the woodwork was all redone by the previous owners. Some of the other things they did were a bit shonky, so I'd like to check the plaster doesn't go down to the floor or something silly. It would be the room with all the biggest & heaviest furniture in it... :rolleyes:

DVardysShadow

never_enough wrote: »

Thanks for replying.
I think we're just going to have to bite the bullet & move all the furniture out, then get the boarding & carpet up to have a look. I'm going to take the skirting board off as the woodwork was all redone by the previous owners. Some of the other things they did were a bit shonky, so I'd like to check the plaster doesn't go down to the floor or something silly. It would be the room with all the biggest & heaviest furniture in it... :rolleyes:

OK,double check if the have some boards up [I thought you said the floors were solid?]. It may be that plaster was swept under the floor during the previous work. Being a 1920's house, the plaster will be lime mortar, which is quite effective at gathering moisture - it may be rotting the floor too. For me, this is the best fit to your symptoms, in that the lime mortar is making moisture available, which then condenses behind.

Otherwise is there any pipework under the floor in this area?

never_enough

DVardysShadow wrote: »

OK,double check if the have some boards up [I thought you said the floors were solid?]. It may be that plaster was swept under the floor during the previous work. Being a 1920's house, the plaster will be lime mortar, which is quite effective at gathering moisture - it may be rotting the floor too. For me, this is the best fit to your symptoms, in that the lime mortar is making moisture available, which then condenses behind.

Otherwise is there any pipework under the floor in this area?

Hi, no sorry, that's me not describing things very well.
It is a solid concrete floor, but on top of that are [STRIKE]boards[/STRIKE] big sheets of chipboard with the underlay & carpet on top of that.
No pipework as far as we know, it wouldn't make much sense as all the water is at the back of the house to this, but it's not impossible of course!