Vertical damp

[simonsaysthis]

Hello. Our Victorian terrace house is built with the garden wall continuing as the party wall for the property. Water is sucked into the interior of the house as it was built without any vertical break or damp proof course, it’s just one long wall. I removed the concrete render from the interior and have used lime mortar instead. I suspect that the (modern blue paint) painted garden wall is trapping water and I should remove that to let it breathe but wonder if there’s anything else I can do. My neighbour has a brick extension built against the other side of the wall so they are somewhat insulated from the problem I suppose.
Could I chisel out mortar to create a wobbly lined vertical joint (if that makes sense?) that I could fill with a plastic dpm and then lime render over it? Or inject with a DPM filler or rods? Could that be done outside but close to where the back wall of the house connects with the garden wall or should it be done indoors?
Any tips or comments appreciated. simon

 

[gasbanni]

Your on the right track the paint is impervious water is being drawn in to the wall and can't evaporate. So it makes its way out by coming in to your house.

Water can be pulled in by capillary action through microscopic cracks in the paint and cement rich mortar.

Get the paint off ( sandblasting ? ) remove any rich cement mortar and repoint with a good lime mortar, you could then lime wash the wall, if you wanted.

Or take the wall down and rebuild it with a membrane and air gap.

 

[simonsaysthis]

Thank you. The situation is aggravated by the fact that the garden wall leads uphill into the garden ie down towards the house.
I’ll price up sandblasting and perhaps have a go with a hot air gun in the short term. You don’t think that inserting some form of plastic membrane into the mortar bead between stones close to the house would be worth it, in a wobbly vertical direction?

 

[Notch7]

You could run a grinder down the wall as close to the door frame as possible. Use a min grinder and go as deep as possible say 40mm.

then put in a DPC, wedge in place with silicone and then cover with a trim painted to match the door frame.

Internally or externally.

in an ideal world it would be done behind the door frame, but as thats already there, adjacent is an option.

theres no guarantee the depth would be deep enough to prevent the damp showing internally on the face, but theres a reasonable chance -it depends how much the internal part of the wall gets damp

Is there evidence of damp coming up from the floor?

 

[simonsaysthis]

Great idea. I guess I could do both. Water is definitely just tracking in, it’s a patch about 30cm x 30cm about 4 foot off the ground.

 

[^woody^]

I removed the concrete render from the interior and have used lime mortar instead

Interior of the house? Cement render would be acting as barrier to damp, something that lime won't do. Normally if the cement render has failed, then it should be replaced with cement render.

Your neighbour should be getting the same dampness, unless there render is still intact and performing well.

 

[simonsaysthis]

Hi. The problem was worse with cement (which was rendered over the stone and lime mortar wall) as water travelled further along the wall behind it. Neighbour has a modern brick interior wall against the face of theirs and their side of the garden wall isn’t painted.

 

[^woody^]

Hi. The problem was worse with cement (which was rendered over the stone and lime mortar wall) as water travelled further along the wall behind it. Neighbour has a modern brick interior wall against the face of theirs and their side of the garden wall isn’t painted.

But if the wall is the party wall then surely the damp runs in on both sides of the party wall, and the extension won't alter that fact.

The cement render would normally be continuous to prevent any creep around it. When it fails, which does happen in time, it is renewed in cement render or a waterproofing product, not breathable lime.

 

[Notch7]

Great idea. I guess I could do both. Water is definitely just tracking in, it’s a patch about 30cm x 30cm about 4 foot off the ground.

are you sure its not rainwater running down the neighbours extension and soaking into the wall at the top or his side?
vertical walls catch a lot of rainwater which of course all runs down.


the neighbours extension looks like its a separate but very close -there could be years of crud built up and is damp all winter

the damp may not be from the garden wall your side

the neighbours side may not have exposed wall -its quite likely a false wall or barrier is built in front so he sees no damp internally