Plaster after damp work

FreeBear

A 1920s house will be plastered from floor to ceiling, and then the skirting boards fitted - The plaster used at the time would have been a lime mix with coarse sand. To the untrained eye, it could easily be mistaken for a friable mortar.

If the affected wall has a cavity, I'd suggest drilling a hole through a mortar joint (say about 200mm above the DPC) and insert a small camera to see if the cavity has any debris in there. You can get some cheap USB bore cameras off ebay for peanuts.

I had a long standing damp problem on a wall here. Fixed the leaking down pipe, and still had damp problems. Removed some bricks above the DPC and scooped out the best part of a wheelbarrow full of sand and brick scraps. The only way that material could have gotten in to the cavity was from sloppy workmanship when the house was built back in the late 1920s. Wall is nice and dry now, and spending £x,xxx on injected DPC & waterproof render/plaster would have been a waste of money.

northwest1965

Doozergirl said:

And what does it look like down below? 

The wall below looks like the wall above and below dripping pipe,  I'd say to the untrained eye, looks dry. 
The photo below is the outer wall of the plastered work. This area never gets any sun. On the quote they said they were going to treat it with Storm Dry Masonry Cream. Having read about that, am I correct in saying that, it's useless on painted walls. 

Doozergirl

It's useless, full stop. It's snake oil. 

I renovate old buildings.  Without fail, any house that has had this treatment hasn't had the original source of the damp fixed. 

Old house are designed to breathe.  The mortar is actually designed to take moisture from inside a house and draw it out.  Things happen to interrupt the equilibrium, like leaks, but that this treatment really doesn't help.  It's never 'porous' bricks, it's what they're being subjected to. 

The waterproof render just hides the damp in the wall behind, but over time it continues to creep up and eventually crosses over the 1 metre point.  I come along a decade or so later, go and find the real source of the water and do the simple job and actually fix source, let it dry out.  If it's something that hasn't yet had the 'damp specialist' treatment, we only replaster (not render) if it actually needs it.  

What's unusual with yours is that the render clearly isn't doing its bodge job of hiding it either.  I'm wondering if it's even been done.  I wouldn't want it done anyway, but you're still left like that and the best way is really to isolate the problematic.  We do that by looking at what is around that wall, so I'm still interested to see the bottom of the wall, but also what is on the other side of the internal wall as it seems to be an internal corner there?  

northwest1965

The internal corner is the terraced house that joins ours.
In your opinion, where should I go from here??

Doozergirl

What does your neighbour have on that side?  Is it possible there's a leak over there?  

I'd be looking everywhere for the source of the water.  

northwest1965

Doozergirl said:

What does your neighbour have on that side?  Is it possible there's a leak over there?  

I'd be looking everywhere for the source of the water.  

Would the best course of action be a independent survey for this?

Doozergirl

If you can't find it, yes. 

A paid for survey by someone who does not sell any kind of damp proofing solutions.   Your landlord has already been hoodwinked.  

It could even be a problem with the flashing at the join to the extension.  I have seen roof problems that only manifest themselves at ground level.  

'Blocking' the water is not a solution.  It has to be stopped.  

northwest1965

Doozergirl said:

If you can't find it, yes. 

A paid for survey by someone who does not sell any kind of damp proofing solutions.   Your landlord has already been hoodwinked.  

It could even be a problem with the flashing at the join to the extension.  I have seen roof problems that only manifest themselves at ground level.  

'Blocking' the water is not a solution.  It has to be stopped.  

I am the landlord!😁
Funny you mention the flashing joining next door, tenant has advised of small leak in upstairs bedroom. Our property maintenance company is sorting next week

Doozergirl

Oh, now I understand.  I couldn't work out why you rented and house and owned one! 🤔

FreeBear

That dwarf wall separating the two properties would be my first suspect... But would still check the cavity for debris..

I would expect a DPC to be just under the door, so what ever they have injected in to the wall has been done too high to be of any use. Tanking internally without removing the skirting boards was a pointless exercise and still leaves a path for damp to get through.