Damp in interior wall

Hi there,

I am currently in the process of preparing my house to be put on the market. The walls in our front room desperately need re-skimming because of the state of the plaster.

I have noticed for some time that we have a damp problem. We already have a dpc installed and a 30 year guarantee. The company who installed the dpc have tested our walls and advised us that the damp is due to salt migration in the wall.

They have advised me that the best way to tackle this problem is by dry lining the wall. They have unofficially given me a quote of £500 to fully complete the job. Is this the only way of tackling the problem?. I thought maybe I could install an air brick as the wall is 1 brick thick, to provide more ventilation and dry the wall out.

Any help would be gratefully appreciated.

Thanks in advance.

If it is due to salts on the wall attracting moisture from the air, then the best solution would be to hack off all the plaster and replaster it (pref mortar with hard plaster skim).

Hacking off will remove the old salts which will have migrated to the surface of the old plaster.

Dry lining might be cleaner, but not "best"

Dino Baggio said:

I thought maybe I could install an air brick as the wall is 1 brick thick, to provide more ventilation and dry the wall out.

Click to expand...

Are you quite sure the wall is only 1 brick thick, ie 112mm.?
Single brick is only used on internal walls . I get the impression you are talking about an external wall.
Let us know so we can provide a more accurate diagnosis.

Yes, myself and the company who tested the wall for damp were both surprised the exterior wall was only 1 brick thick. It is an exterior wall of a terraced house, the wall is under a passageway. So the damp wall in question is not directly accessible to the elements etc.

Hope this explains the situation clearer. Many thanks for replying to my query.

Whoa there Dino....

The company told you what? Salt migration???


Let's start at the beginning: An injection DPC is a two part process. The first part, i.e. the injection 'controls' the rising dampness and the second part; the re-plastering, prevents residual moisture and SALTS from migrating to the surface of the wall.

If it's salt migration, which it probably isn't, then the plastering specification hasn't met its design functions. End of story!

The most likely explanation for this dampness isn't rising dampness or anything else other than condensation. The wall you're talking about obviously doesn't receive sunshine, just a cooling draught as the air vents through the pasageway. As it's single skin its insulation value is very very poor.

The 'dry-lining' is by far the best way to treat this, but it should have been the first option. The installation of an injection dpc without considering the possibility (strong in this case) of condensation is ........ (space for own description).

HTH

Patrick

so a good opportunity to include insulating bats behind the lining, too?

Absolutely John!

Tanalised 25x50 laths, 25mm Kingspan and foil backed plaster boards. Job's a good un!


Patrick