Mould coming through plaster skim ?

[SimonH2]

A friend has had the kitchen walls skimmed - they were a bit rough to start with, then we set about chasing out electrics etc
Anyway, quite predictably, when we ripped the old kitchen out, behind some of the units there was damp - which my mate treated with bleach (that was a few months ago). 1960s bungalow, block walls ('kin hard block at that), the inner leaf blocks have what looks like PU foam insulation on the back, no cavity insulation (yet).

Now the wall has been skimmed (this one is near enough external, it backs onto the garage), it looks like the mould has come through.
Is this the problem or something else ?
Should he be worried about it ?
Should he do anything, and if so, what ?

Skimmed wall 1

• SimonH2
• 10 Mar 2013
• 1

Skimmed wall showing what looks like mould coming through.

Skimmed wall 2

• SimonH2
• 10 Mar 2013
• 1

Skimmed wall showing what looks like mould coming through.

These photos were taken about 5 days after this wall was skimmed. The other 3 walls were skimmed about a week earlier.
There's a few damp patches which are where holes* were filled (binding?) before being skimmed over. Apart from that, the blotchiness is obvious.

* Eg, there used to be a single socket below the new double backbox, to the right of the drain pipe. Also, you can see where the old cooker connection was, and the diagonal cable run up to the switch.

 

[JohnD]

what makes you say it is mould?

What did you do to cure and to dry out the damp?

 

[stevethespreader]

the chases with bonding will take longer too dry out as the bonding has to dry to as well as the skim, i must say though that the skim job is pretty poor quality and im not sure your allowed to do diagonal chases like that i may be wrong though

 

[joe-90]

Yeah you are wrong. The cooker connection is done like that from the isolator switch.


Actually having another look it looks like it's been an old one that is redundant and filled in.

 

[SimonH2]

what makes you say it is mould?

I'm not sure it is - but it's in the areas that had mould before. I guess it could just be staining from the treated mould that's come through.

What did you do to cure and to dry out the damp?

At the moment he's got a small dehumidifier running. The mould was in the usual place you'd expect - outside wall, dead air behind cabinets (another reason not to have false backs), and the washing machine was that side (you'll see it's worst where the drain for that was).

the chases with bonding will take longer too dry out as the bonding has to dry to as well as the skim

Obviously

i must say though that the skim job is pretty poor quality

I thought it looked quite good - the photos make it look poor because they highlight the variation in colour while it's still drying out (my mate was amazed how much water went into it !). Is there anything specific you'd say is poor ?

and im not sure your allowed to do diagonal chases like that i may be wrong though

You're correct, a diagonal chase isn't allowed - that's how it was originally (and there was an "abandoned" hole where the original kitchen fitters had hit the metal capping and had to drill a different hole ). If you look, there's a damp area where that chase and the old position of the connection unit are filled in, and new boxes with conduits in the correct safe zones. The dual box is to allow for any combination of CCU, 13A socket or FCU to suit what appliances get fitted.