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Rising damp

RogerS

RogerS

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Hey ho. Probably never had any DPC. So got a bit in a few walls. Nothing to do with higher outside soil levels or leaking pipes. So coming up through the ground.

Suggestions please. Do these injection systems work ? Rooms are tiny so reluctant to stud wall and tank the room.

TIA
 
Yes. Mine was a 9" solid brick wall, three holes per brick, double drilled. First holes, to centre of bricks in outer leaf, injection of silicone, second holes to middle of second leaf, injection of silicone, plug. No disasters, no smells on the inside.
 
Victorian terraced I renovated had damp, the floor was terracotta tiles with just compacted earth underneath. All dug out and dpc, concreted etc, it was a major job but solved the problem, including drying out the adjacent cellar.
My understanding is that rising damp is vanishingly rare and all these injection things are just snake oil.
 
When we bought our current place there were signs of damp in the corners of the rooms that were north facing. The house had been empty for some time.
We had a bit of mould for the first two winters ( moved in a December ) but it’s gone away.
I put it down to lack of ventilation and the inner course of brick and plaster needed to dry out.

Just suggesting you might be worrying too much.
 
Just to confuse things: a solid wall, brick or stone, will 'conduct cold' onto the inner (room) surface. This cold surface then preferentially is damper, ergo, mould. ESPECIALLY behind wardrobes. I did my house's bedrooms outer walls with.50mm Celotex/faced plasterboard, dab and dotted, backed up with 6 sheet anchors per 8x4 sheet, then skimmed to a finish. No mould in 20 years.
Sam
 
SamQ aka Ah! Q! said:
Just to confuse things: a solid wall, brick or stone, will 'conduct cold' onto the inner (room) surface. This cold surface then preferentially is damper, ergo, mould. ESPECIALLY behind wardrobes. I did my house's bedrooms outer walls with.50mm Celotex/faced plasterboard, dab and dotted, backed up with 6 sheet anchors per 8x4 sheet, then skimmed to a finish. No mould in 20 years.
Sam
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No mould that you can see. If any vapour can get to the wall, though, through or around the insulation, then you might have mould just where you had it previously, but now covered up by the insulation. The boards should have a built-in vapour barrier to reduce the risk.
 
RogerS said:
Some sort of stone and wrong type of pointing
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Yeah, that pointing looks poor.

Is there a cavity? Is there a different material on the inside skin/ face of the wall? If you've got a solid stone wall then you can forget injecting a DPC.
 
I bet you get a lot of splashing up the wall from those down pipe gulleys. I am not a fan of tarmac right up to the wall either. It is amazing the difference a bit of gravel makes.
 
Mike G said:
Yeah, that pointing looks poor.

Is there a cavity? Is there a different material on the inside skin/ face of the wall? If you've got a solid stone wall then you can forget injecting a DPC.
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Almost certain it’s not cavity. Victorian c. 1830
 
If it's stone all the way through (stone-"rubble"-stone), then an injected DPC would be a waste of time and money. You're then into the classics of maintaining an old house in a dry condition: warmth, ventilation, and good detailing, particularly around the base of the walls externally.
 
Mike G said:
No mould that you can see. If any vapour can get to the wall, though, through or around the insulation, then you might have mould just where you had it previously, but now covered up by the insulation. The boards should have a built-in vapour barrier to reduce the risk.
Click to expand...
Agreed Mike. The ones I used had a 'tinfoil' layer incorporated and we were careful to seal the base and top too.
Sam
 
These older properties had open fires and plenty of ventilation which kept the damp at bay, modern heating systems tend to just draw the damp out.
 
PAC1 said:
I bet you get a lot of splashing up the wall from those down pipe gulleys. I am not a fan of tarmac right up to the wall either. It is amazing the difference a bit of gravel makes.
Click to expand...
That was my reaction when I saw the photo.
 
Does the tarmac also fall towards the house? So that the wall then channels rainwater to the gulleys.
 
I have rising damp despite having a very good DPC. When building the bungalow in 1950 the builders applied the scratch coat of sand & cement before the floor was laid and applied it across the DPC. The concrete floor was then laid without a DPC, the skirting fitted and the final plaster coat applied. As the DPC on the external and internal walls is at least 4 inches above the finished floor levels there is a route for damp up to and across the DPC. The concrete floor has plastic Marley tiles which is the DPC for the concrete. The result is rotten skirting and damp plaster even on walls over 10ft from the external wall.

The fix I have used, which may not be relevant to you, is to dig out the sand cement around the circumference of the concrete, the plaster behind the skirting came off when removing the skirting, and applying two coats of damp proofing paint on the brickwork up to the DPC before re-plastering and fitting new skirting. So far so good but I won't be around to see if the skirting is rotten in 30 years time.

I installed a Positive Input Ventilation system for a client who had solid sandstone walls. It had been recommended by his damp proof specialist. It worked for him. They are frowned on in some countries as it is inputing cold air into the building forcing warm air out. It is however ensuring adequate air changes after we have sealed up the windows and doors to stop draughts. Even better is Mechanical Ventilation Heat Recovery but that is difficult to fit retrospectively.

I just have dogs which results in the doors being open most of the time anyway.
 
Looks like 'Dutch mortar' walls.

Had the same in our last place. You can inject, between the stones obviously, but it needs a lot of liquid, as the middle is a hollow rubble-fill, but it did work for us. I used Sovereign chemistry back then and a hired injection pump. Beware of injecting bricks, as the older ones were often not very porus, and a decent pump can cause spalling to the outside.

It was done in our present place long before we arrived, but the bricks are very dense and it was utterly pointless.

How are your floors constructed?
 
Cabinetman said:
I’m just looking at that wire thing connected to the wall, is it a redundant anti damp system?
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Interesting spot, Ian. I’d noticed it but not paid too much attention. Too many other things to investigate. Like WTF when he fiddled about with the electrics didn’t he take out the old wires where possible. Or when fiddling about with the CH and plumbing didn’t he sanitise what was there. That would have meant my plumber not having three leaks to contend with. ….sigh…
 
Cabinetman said:
I’m just looking at that wire thing connected to the wall, is it a redundant anti damp system?
Click to expand...
I wondered that too, also if it's some sort of ground connection for incoming services, or part of a lightning conductor installation. Discounted the latter, as the wire to ground isn't really big enough.

The anti-damp systems don't seem to be effective, but people love thinking they're buying a high-tech solution to a difficult problem. There never seems to be a world shortage of oily snakes...
 
That electrical thingy looks to me like and old GPO incoming cable.
 
looks like the wrong mortar was used, maybe that's the problem, re-point it with the correct mortar type, if victorian and 1830 it's likely hot lime mortar was used.
 
IIUIC, that kid of damp cure relied on a small but permanent DC current between the metal plate and the earth, and uses electrolysis to drive the water downwards. Don't connect it back-to-front...
S
 
Generally or just in this specific instance.
 
Mike G said:
Oh, I disagree. It's purpose was to remove money from the unsuspecting, and I think it did that pretty well.
Click to expand...
Along with, as far as I can tell, the entire damp proofing industry in this country, starting with the idea that a two-prong moisture meter designed for timber can give a meaningful reading in plaster and going from there.
 
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