Creeping Damp On The Living Room Wall

[njwilson]

A bit of background: The house is ~1860 and has no practical DPC to speak of (engineering bricks and slate at the base of the foundations). After digging out parts of the bay window for expanding the airbricks (they were badly installed - above floor level, behind the skirting boards - when the house was first built and there were serious sub-floor damp/rot issues) I found that there's a rudimentary cavity of an inch or so within the wall (filled with sand/rubble up to about 4 courses of brick). I don't know if this extends to the rest of the wall. The water table is high in this area, so any prolonged rain turns the soil underneath the floorboards to a 1-2" pond.

I moved into the house in late November, and there was a damp patch on the living room wall next to the window, spreading from the shallow bay to the wall shared with the hallway. There's a later patch of plaster immediately below the staining that corresponds to the same width - if the newspaper found packing out the skirting below it is anything to go by, the patch dates to 1956. It's the original lime plaster above this. There was a heavy build-up of salts at the join between original and later plaster. The later patch seems dry to the touch.

Currently, the height of the stain is just shy of 1m above outside ground level.

I marked the edge of the stain at the beginning of December, and it had grown a little by the beginning of January. Then it was static. Over the last couple of weeks, it's grown by a further inch in places. Despite recent inclement weather, it doesn't seem overtly linked to it - there was plenty of rain and cold between January and April.

The damp seems only to be on the very surface of the plaster. I chipped a little away that was loose and crumbly, and it's powder-dry behind. There are wood fillets in the wall for the wooden corner beads to attach to, and this is all dry and sound. There's a build-up of salts behind the plaster, on the bricks, where the old/new parts joined, too.

To the outside, in the same spot, is the ugly plastic meter box, which also comes to about 1m above ground level, but everything seems dry and there's a small gap behind it for air flow. There's some occasional deterioration to the pointing, above where the damp patch is that I'll get around to repairing shortly, alongside chipping out some badly-applied concrete pointing.

Next to the meter box, the sandstone sill has heavily deteriorated, too. Even in the corner, where's shielded by the box. I've looked outside when it's raining, and there is little rain that splashes off the box and down the side, and nothing tumbling down from the gutters. The house has Italianate/gothic stylings, with a slightly overhanging second floor that shields much of it. Indeed, there's a pile of dry sandstone dust in the corner completely unaffected by rain and wind, it's so shielded.

In the bedroom directly above the living room, there's a large damp patch in not quite the same area that seems to be caused by faulty/blocked guttering and/or a knackered bit of roof (getting someone to look at it next week, hopefully). This seems to an old problem, with the wall being patched in more modern gypsum plaster (now falling off).

So what is more likely? Water making its way down the wall from the second storey - possibly through the wall cavity that may or may not exist - and settling downstairs? Penetrating moisture from driving rain on damaged pointing? Something to do with the meter box and/or the deteriorated sill? Or could it be the incompatibility of breathable and non-breathable finishes where it's been patched over the years?

The house is a sad and abused mess, generally, so the budget for any one urgent project is tight - so if anyone could guide me to the most probable cause/s I'd be very grateful!

 

[Mr Chibs]

Until others arrive...

The outside ground looks too high, whatever DPC you have slate etc could be below ground level, so damp has bridged and travelled upwards. (rule of thumb, air vents should be two courses of brick higher than ground).
I would lower outside ground, or at least chop a trench 200mm all the way around the house fill with large pebbles or empty (easy job).
Dryrods, can be drilled into mortar line, around £20 per metre, DIY (easy job), this will give you a new DPC.

You don't have a cavity wall, looking at your brickwork, so it's more than likely solid 9" walls.

As for the damp high up in the room, would guess it coming down, but we'd all need to see photos of the outside please.

 

[njwilson]

There's no useful DPC - there's slate and engineering bricks directly on top of the foundation bricks... and that's it. And they would always have been buried under ground. There's a rudimentary French drain already in front of the wall, in the garden, but it's not nearly deep/wide enough and was clogged with weeds (it's since been dug out a little, but I need to do away with the concrete path and do it properly).

When it comes to the damp travelling upwards... the bare brick wall below floor level / behind the skirting, directly below the damp patch, is quite dry and dusty - as is the wall behind the stain where I've chipped the old plaster off, with very dry wood embedded in the wall. The damp outer surface is the opposite - it's tacky and very noticeably wet. That's what's confused me.

There is a cavity - at least in the lower part of the wall in the bay window. I spent 20 minutes raking damp-ish sand and rubble out of it.

 

[Footsoldier888]

Interesting bricks you have there. What is this Italianate gothicdom you speak of, sounds interesting.

Not sure if you should have raked the sand and rubble out tbh, it might be there to bind the wall together and not a cavity.

As for the damp both the window and door are showing signs water may be getting in. The thing to remember is it only takes a small amount to cause this effect, even a cupfull can show up. It doesn't look like a big problem at least.

 

[njwilson]

That's mine, on the left - all polychrome, pointy bits, arches and corbels, like the architect got a copy of Ruskin's 'Stones of Venice' for Christmas and wanted to have a go at all of it on the cheap.

As you can see, though, no one has been kind to it for a long long time. On the plus side, at least no one decided to pebbledash it or smash it up to put in landscape windows - which has happened to nearly every other one on the terrace.

Whilst both the door and windows are undoubtedly crap, they don't seem to have any associated damp on the walls immediately around them. The hallway walls are quite dry, for example (even found a few scraps of perfectly-preserved Victorian/Edwardian wallpaper whilst scraping off the horrible textured 1970s stuff currently on it, and the damp in the living room seems to be isolated from the windows (although the plaster immediately around the windows is pink gypsum plaster, which could be trapping moisture underneath it) and seems worst in the corner furthest from the window.

The rubble and sand in the cavity was above the airbricks as well as below them, and had blocked them up. I'm not entirely sure it's original to the construction, and may have been from when a past owner ripped out the sash windows, filled in the arches and bunged in cheap/nasty square casements. In any case, I didn't take it all out, just whatever I could drag out from over and around the airbricks to stop them getting blocked again.

 

[Footsoldier888]

Wow you really have something to work on there, all it's missing is a few Harry Potter creatures (joking!). I particularly like that corballed porch cover. and the recessed bits. The proportions are right too. All you have to do now is start collecting Pugin objects with which to fill it. Or a set of William De Morgan tiles. Perhaps you will be able to find out who the architect was.

Lol I have the same bloody door on my house and have hated it for years now! The thing is with damp it could be any of these things including the crack in the sandstone bridging it. Or even condensation if they didn't use much ventilation and there was something infront of the wall. The point is it's not bad, it isn't all round the walls so is a localised issue. Why not hack off and leave the bricks to dry out over summer and tackle the bits outside. Keep it well ventilated so you don't get any dry rot issues. Things could be a lot worse, it looks like you are just in time. Hack back, heat and ventilate and see how it goes.

It might be that the sill is no longer working properly and water is being directed onto the brickwork below instead of away. Looking at the base someone has filled that corner with mortar. Water bouncing between the meter and the bricks doesn't help matters either. Perhaps you could look to place the meter between the brickwork in time? Also removing any earth under the gravel would help.

 

[njwilson]

It was the frontage, and the original cornicing inside, that really drew me to the house (that, and it was ridiculously affordable because it had been trashed and bodged by successions of lazy landlords). Apparently this terrace was profiled some years ago by the local rag, and do have an architect name attached, but I've not been able to track it down. The terrace would have looked pretty smart, in the days before pebbledashing everything. From a row of 18 houses, only 6 are relatively unsullied (3 3-storeys and 3 2-storeys). Here's how they should have all looked - more or less (the swag effect created by the bricks on the ground-floor window arch on the 2-storey is a particularly nice touch, I think):

I think you may be correct about the sill being the main issue. I went back and had a look, and stupidly I never paid attention that the patching on the wall, both sides of the window and under the bay is at the same height as the sill outside. On the right side of the window, the patch has been extended upwards - meaning it may have had similar issues that I'm having on the left side that were just covered up rather than resolved. It also means that the sill might have been awry for a long time, if the first patch comes from the 1950s. Will have to price up getting a new sandstone sill installed. I knew it would have to be done, but I was hoping that it could be something I could kick into the long grass for a year or so.

Still odd that the damp seems worst in the corner furthest away from the window, though. It's just the path of least resistance, perhaps?

 

[Footsoldier888]

Perhaps that could be condensation, there is often more than one cause with things. Good luck with it, you seem to be well on the way now.

 

[njwilson]

I had wondered if it was impermeable plaster pushing water up into the old lime plaster, because of all the salts accumulating at the join between the two, but I've isolated the old from the new by chipping out a channel back to bare brick (seen in my last photo) and the damp patch is still growing.

Although, isolating a small patch on the right of the damp from the rest of it, has stopped growth in that one spot, so I'm wondering if there's water ingress behind the old plaster, on the left side where it looks worse, from the outside wall - possibly via degraded pointing.

I'll have to investigate further - most of the plaster in that lower corner will need to come off anyway as it's quite powdery.

 

[^woody^]

Firstly is that house haunted? If not it should be.

It's penetrating damp and the most probable cause is defective pointing.

Stone cills need re facing too.

Then when it's all done and clean, a silane water proof coating may help

All of the affected plaster will need to be removed and replastered.

 

[njwilson]

So far, I've only been haunted by the mounting cost of the repairs.