Re: is this some sort of damp ?

[robgraham]

> Is this blistering some sort of damp ?

> > It is appearing on an internal wall - what is it and what can I do to sort > it out.

It looks like damp. How far up the wall is it? Does the wall have a damp-proof course? It looks as though the damp is rising and bringing salts with it which remain when the water evaporates (rather like the way a stalagtite forms) and cause the plaster to come off. I imagine that you could scrape it off with a scraper and that you'd be left with bricks with a slightly crumbly surface. If my reasoning is correct you'd need to get a DPC in somehow. This could be injected by either yourself or a professional firm.

Rob Graham

[dg]

It may be, or it may be some other reaction.

What is on the other side of the wall, and what is the wall construction? When did this first appear? Does its appearance coincide with any rain? What is the room used for?

dg

[rocyn]

i guess it is at ground level

but

the wall is an internal wall - it is not outside facing

construction?

[dg]

The dampness appears to be forming along a horizontal plane, and if this is at ground level, then it is possible that moisture is creeping along horizontally. Cracked mortar joint is a common facilitator of this.

Another possibility is that this is a form of condensation dampness, where warm air has been condensing on a cooler wall - this is common during dry spells, and especially at the junction of a cold basement and warmer room above.

If there are no other possible ways for moisture to have reached this spot by travelling down the wall (such as a leaking pipe or roof), then DPC failure or bridging is the most probable cause.

For a proper diagnosis, a surveyor or rep from a damp treatment company may have to have a look.

If you want to DIY, then do a search for injected damp proof course or similar.

Bear in mind though, that you may need a vertical and horizontal barrier, and if there is excess moisture in the ground around the wall, then this may have to be addressed too.

dg

[NJF]

We have patches like this on the 4th floor here, from roof and air con. leaks tracking down inside a wall to a solid floor then going sideways to a wall that effectivily doesn't terminate on a floor slab, I.E. the stairwell, the plaster at the point it crosses the slab is worst affected due to concentration.

Look for the ingress point, it might be external, or it could be a small leak tracking, before getting the big guns out.

Niel.