Mysterious damp bricks internal wall Victorian house

[Previouslyunloved]

We bought a very unloved house 2 years ago.

We replastered and decorated and found that there was 2 persistent patches of damp that kept coming through.

We have recently stripped back the plaster back to brick in these areas and can see that previous owners must have had the same issue as they had covered the wall in 3 different layers of cement tanking (which can’t have worked as the moisture was still coming through)

The angle beads were all rusty.

I thought the wall would start drying out now we stripped it off but it’s just staying the same. It’s not growing or getting any less.

We ran a dehumidifier for a bit which made it appear dryer on the surface after it had been running for a while but after a day of being off the moisture in the wall appeared to the exact same place again.

What’s a mystery to me is this is on an internal wall. The other side of the wall is dry (possibly been damp proofed by previous owners)

Its been weeks of me trying to rule different things out and I’ve got to the point where I have no ideas left and I’m tempted to get the damp people in.

(Previously damp people have been round when we first bought the house suggesting the room needed their treatments but i held firm and said it couldn’t possibly need it)

Can anyone give me any ideas?

 

[george2019]

It being an internal wall rules out horizontal penetrating damp.

Some other ideas...

Does the wall go up to a roof valley?

Is there a large temperature differential between rooms on each side of the wall?

Is there a source of moisture nearby (eg a kitchen or shower) that could be pushing water out and this is the first cool spot it hits?

Are there concrete floors on each side of the wall pushing moisture up into the wall?

However, I suspect if you remove impermeable plaster from both sides of the wall then that might alleviate the problem.

 

[Pennyviz]

What's the flooring? I had a similar problem caused by broken drain gulley outside kitchen which then soaked under kitchen floor (which had effectively been tanked under numerous layers of tiles and cement) to internal wall.

Alternatively I also get 'cold spots' in the house where condensation occurs in corners.

Other than than that usual questions about what is above, possibility of leaking water pipes etc

Penny

 

[steveb]

how long have you exposed the wall - wet walls take months to dry out. Something like a day per mm of thickness or the wall rings a bell. And that if course assumes there is no actual source of new water - such as a pinholed heating pipe.

 

[Gothichome]

Previousunloved, are your bricks soft bricks by chance. We had the same issue with an interior basement wall. Each of the bricks had swelled enough to cause a 5cm bump on the kitchen floor. The bricks were laid on earth and cement poured as a floor. The wall had nothing to support above so I suspect it was there to delineate two rooms in the basement. To fix my issue I installed a telepost as insurance in case I was wrong and removed the top layer of brick. This removed the bump in our kitchen floor. Everything has been stable for years. Shortly there after I was proactive in drying out the basement by putting it into the heated space envelope. Now five years on the wall is bone dry but the once damp bricks are now turning to dust.
Unless your issue is a basement install my fix will not be any good to you. But, the end resault of your bricks turning to powder after they have dries out might be some thing to think about in your planning.

 

[Previouslyunloved]

Thank you so much for responding.

the wall doesn’t go up to a roof valley. There probably was a considerable temperature difference in the past. Since we have owned it there is still a nominal difference but the wet side of the wall is seemingly warmer since we have removed the door seperatingbthe rooms and adding a radiator.

I can’t see any source of moisture other than that 2 years ago we had a leaky pipe under the floor which was capped off.

The floor on the wet side of the wall is old concrete. The other side is timber with a void.

The impermeable plaster has been removed and it still looks very wet up to a height of 3 bricks. The top of the 3rd brick feels slightly dryer but the base brick is still very wet.
The walls have been exposed now for about 4 weeks.

Heating is recently been pressure tested so the only chance of a leak is from underground pipe work.
I’m going to get pipes rerouted just to cancel that out.

The bricks seem soft I guess. Some are a bit crumbly.

My husband got a damp proofing company round and they quoted £7k inc vat to tank the room!

 

[Previouslyunloved]

I had thought about a broken drain gulley but it’s bren so dry the last few weeks and I’ve dug down outside and can’t see any sign of any issue.

 

[Previouslyunloved]

Is it possible for it to be rising damp on an internal wall?

 

[Pennyviz]

Is it possible for it to be rising damp on an internal wall?

is it possible to tell where the damp is worst? if the bottom metre then probably rising damp, if in a corner then condensation etc. If the layout is timber floor then wall, then concrete then another possible 3 tanked walls, could the moisture be travelling from one of the other 3 sides? What is under concrete?

The moisture is obviously coming from somewhere - if not above, then across or possibly just up from a random spring. If the concrete is laid on bare earth then any moisture will inevitably escape through the walls instead.

Penny

 

[Previouslyunloved]

It’s worse at the bottom 3 bricks and it’s spread across the span of the wall except for one small area where there is no damp

The concrete is directly on earth. No DPM.

 

[Previouslyunloved]

It’s 1905 build

 

[MatthewC]

The floor on the wet side of the wall is old concrete. The other side is timber with a void.

So what's it like on the ground under the wooden floor? Are you saying that that side of the wall is dry?

I'm having trouble picturing this. Does the dampness start on the concrete floor side, at the level of the concrete? If so then it sounds as though there's water under the concrete...

 

[Previouslyunloved]

Yes the wall on the side where the wooden floor is is dry.
It’s just the concrete floor side that still damp.

We did have a mains leak under the concrete 2 years ago - could it be the moisture in the wall has been trapped all that time?

 

[Pennyviz]

Are any of the room's walls external? it could be travelling under the concrete?

 

[george2019]

Yes the wall on the side where the wooden floor is is dry.
It’s just the concrete floor side that still damp.

We did have a mains leak under the concrete 2 years ago - could it be the moisture in the wall has been trapped all that time?

If the wall was plastered in an impermeable materials then it could well be. Also, following the leak, if the concrete was relaid quite soon, there is potentially a lot of moisture trapped below the slab which is slowly diffusing/escaping.

£7k on tanking would not be money well spent and could damage the wall. Increasing vapour permeability and treating the symptoms: free the wall base of the wall of plaster and dehumidify (never a long term solution but will deal with the result of trapped water). Once dry, re-plaster with lime.

 

[MatthewC]

Yes the wall on the side where the wooden floor is is dry.
It’s just the concrete floor side that still damp.

We did have a mains leak under the concrete 2 years ago - could it be the moisture in the wall has been trapped all that time?

I would think "yes". If water gets under concrete, it can't evaporate through it. It can remain there but if it finds some nice permeable old wall/footings/lime plaster then that would be a suitable place.