salty? wall need advice please

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Meirion Harries

New Member
Hi there,

We're planning to get our dining room area re-skimmed soon, had some quotes for ceiling board, boarding fireplace and skim etc but we have 1 major problem area that we have no idea what to do with.

This wall is under the stairs, an internal wall, there's no sources of water close to here, the house is mid-terraced and it our neighbour's stair case behind this wall. At some point someone has tanked the wall up to a certain height and this is what the wall looks like above, after this pic was taken a lot of this plaster came off very easily. The wall feels dry to the touch... I asked one of the plasterers what he could do with the wall and he said he could PVA and skim it but there's no guarantee it won't come back. Doesn't sound like a road I want to go down. Behind this plaster there's original Lime based Black Mortar.

This sort of salty line runs through to the adjacent wall in the kitchen where there's a disused chimney, across from this wall in the dining room there's another disused chimney, the chimney in the kitchen has been capped under roof line, the one in the dining room is outside and vented.

I've had a look at 3 different options to try and solve this, all which involve hacking back to brick. Iwas hoping for some advice on which you would think is best:

1. The Dryzone Renovation plastering system:

2. Dryzone express replastering system:

3. 2 or 3 coat lime plaster, NHL I guess?

I'm not sold on option 2 at all, just feels like covering it up. Option 3 seems to be for a lime specialist and there ain't much of those around. I'm leaning towards option 1.

Has anyone else used this system? Anyone got experience of these products? Anything else I haven't mentioned which is important?



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Meirion Harries

New Member
Hi Chrispy,

Thanks for the pointers. Since your message I've done some digging. The chimney breast has kitchen cupboards over it on the downstairs part of the chimney breast, on the first floor its been boarded over and there is a stain/wallpaper coming off at the top of the chimney breast on the first floor (all this in pictures attached). I've been in the crawlspace and there's no damp up there, dry as a bone. I can't see if the top of the chimney has been capped or is full of rubble in the crawlspace as its so tight to the roofing felt/battens.

Yesterday I installed a couple of MAP vents in the kitchen baseboard and in the first floor boarding to try and help ventilation. I wasn't sure if I should put a brick one in the attic? Or will this aid condensation up there? We have got non breathable roofing felt but I guess its an old house so leaks anyways :X3:

I've also pulled up a floorboard to have a peek, the water and gas run under this floor, the soil feels dry. I've also seen the neighbours wall on the other side and their wall is in great condition, that house was done up last year though for new tenants.

In one of the pics of under the floor you can make out the original slate DPC which seems to have salty material on it. On another pic you can see drill holes where they've drilled into the brick for a new DPC before the tanking slurry has gone on.

To the right there is a wooden cupboard, could this be acting as a 'wick' and bridging the tanking slurry? I was thinking of trimming the wood away from the plaster just in case this was happening. I tested with a moisture meter and the plaster right at the top(between 1.8m and 2m) is fine, the lower part of the wall with slurry is mostly fine (weird patch where the slurry is bottom right is showing a darker patch). So am I right in thinking I could take this middle area back to brick, let the wall dry out with the aid of de-humidifiers, apply a salt neutraliser then tanking slurry this middle section? Seems easier than removing everything and starting from scratch but don't want to cut corners.


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Meirion Harries

New Member
Oh yeah and here's a pic of the wall in the kitchen to the side of the cupboard under the stairs (blue wall). This is right next to the chimney breast.

And another part of the room where either some wally has installed a socket right over the tanking or the tanking has been taken around the existing socket :tonto: The plaster above this is crumbling.... I want to move the socket anyway but looks like I'll have to keep this one surface mounted.


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Well-Known Member
  • Use the moisture meter to mark (+ the reading) and map out the damp areas to track down the source. Per Tiny Tom, check outside, tiles, flashings and at ground level all round
  • If you have signs of damp at first floor level it is coming down not up. But this might be old.
  • Take out the board over the fireplace and get a cctv up there to look for rubbish/rubble etc and cctv in any accessible or semi accessible chimneys down stairs (most sweeps have them now). Take out some courses in the attic, seal with a slate/mortar and fit an airbrick at the same time.
  • Take the mesh out of the vents and make a proper bigger hole, it's doing nowt as it is. Then there will be a trickle of warm air up out of attic and helping to dry out condensation.
  • Efflorence salts can continue long after the water seems to have gone.
  • Good chance you have top down condensation- cold open brick top in attic (rarely capped when taken down below roof level) draws in moisture, condenses and rolls down.
  • Chemical DPC is totally in the wrong place and has missing sections, 50/50 bet it doesn't go through the cupboards? Smacks of a sales cover-up. Should be at level of old DPC - requires removal of floor boards, and doesn't always work without repeat applications.
  • Meter check brickwork below DPC and underfloor ventilation - I have seen heavy timber condensation due to water running outside near to vents, but its rare.
  • They put tanking over porous lime plaster? Capilliary action will just raise the moisture up until it shows over the top.

Meirion Harries

New Member
I’d be checking the outside of the property something isn’t right the damp is coming from somewhere

Its an internal wall and the wall above this on the stairs is dry. The bricks are also dry, the mortar is in very good condition. There was a broken gulley which also has the bathroom sink/shower waste running into it but that's about 5m from the area we're talking about.

Monkey Boy

Well-Known Member
@Brimstone deserves paying for all that
Only bit I already knew of it all was that them vents ain’t doing anything with a couple of poxy holes drilled behind them - Micky mouse effort those