I noticed that the paint on a wall adjacent to our kitchen back door was 'bubbling up'. The paint has been there about 3-4 years. I rubbed down to the plaster, and discovered salt had formed on the surface.
Can anyone explain what's going on. The house is 22 years old, there are no signs of damp, and the affected area is well away (15 ft) from any water supplies or pipes. It's a small area about 3 inches above the skirting board.
Its got damp from something..pinhole prick in a buried pipe..maybe water blowing in..who knows..apart from you..
Where do you live?
This is caused by damp, normally not rainwater, since rain lacks salts.
NT
You often get salt deposits forming at the _top_ of a rising damp patch Its were evaporation is starting to win Is the floor concrete or suspended wood. How high is the DPC above ground level on the outside part of this wall.
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No shortage of dissolved salts after it has been through a wall.
|!On 19 Mar, 20:06, Mark Carver wrote: |! |!> I noticed that the paint on a wall adjacent to our kitchen back door was |!> 'bubbling up'. The paint has been there about 3-4 years. |!> I rubbed down to the plaster, and discovered salt had formed on the surface. |!>
|!> Can anyone explain what's going on. The house is 22 years old, there are no |!> signs of damp, and the affected area is well away (15 ft) from any water |!> supplies or pipes. It's a small area about 3 inches above the skirting board. |! |!This is caused by damp, normally not rainwater, since rain lacks |!salts.
The salts found in efflorescence come from the building materials not the water. The water only transports them to the surface.
North Hampshire, dig down just a few inches anywhere round here and you hit chalk.
Curiously on the other side of the house, salt is coming out through the exterior bricks. Only a cluster of three or four are affected.
We're half way up (or down :-) ) a moderate gradient, so I don't think any significant flooding is involved ?
Concrete floor. DPC is one brick height above the ground level (paving slabs) on that side of the house.
On the other side of the house, the DPC is 10 bricks above ground level, the salty bricks I mention in my other post are below the DPC, three bricks up.
That may be your problem. Rain bouncing off the slabs onto the wall..
Or driving rain getting into a cavity and dribbling down to on TOP of the DPC.. That might indicate some cracked mortar or even a window frame or some other high up issue.
Yes, no windows at all on that wall, just the door. I do notice the door during/after heavy rain is very wet for about a foot-18ins above ground level. The top half of the exterior walls are tiled. You can always hear them rattling away during gales. In fact that corner of the house faces south west, so it is looking more and more like a rain water problem.
Do you really mean Below the DPC or should that be above ?
No, the salty external bricks are below (7 bricks) the DPC, however this is the other side of the house to the salty interior plaster problem
Don't worry, the external salt that's just appeared is only of academic interest, it's the interior stuff that worried me.
It may be that you have a small lake or river under the house due to the exceptionally damp weather..
I kid you not..
When we demolished my old house the reason for the pereptual damp and rot around the fireplace became apparent. There was a small pond under the wooden floors, and the chimney was standing smack in the middle of a nice moat.
Of course it was not possible to inject that, so they hadn't. It sucked up water after a spell of wet weather like nothing!
That'll be the North Hampshire Salt Pan then.
Yes, but this is only a temporary phenomenon, the salts in the materials are soon leached out. More salt later means not rain.
NT
Sorry I missed that part I thought you were still referring to the damp wall.
Can you see the cement floor next to the damp patch, is this also damp. Has the house cavity insulation It would seem, without seeing it, that either your DPC is damaged or is being bridged.
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The affected area is not damp currently, though I suspect it must have been to have pushed the salt out. The floor is also bone dry.
I don't think so. Never seen evidence of it drilling through the walls, or up in the loft.
Umm, OK. I'll keep a close watch during the next monsoon.
Yes, leaching out of water-soluble salts is a temporary phenomenon, in the same way that Ingleborough caves are just drying cracks. By the time you did wash out all of them, your wall would be crumbling.
Not so really..the water soluble ones come out completely in about 3-5 years.
My brand new chimneys looked vile for a couple of years..now they are fine.
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