Mould on fresh plaster

smokey20

Hi folks,

I’m currently building a new house through a building contractor. It has been internally plastered now about 3 or 4 weeks, however there is a large build up of mould on the plastered walls and ceilings throughout the house and on the window boards and door frames.

Is this normal or anything to worry about - will the mould go away when the plaster and the house is fully dried out? We don’t have electricity yet so cant turn on the heating to help it dry out and we cant turn on the heat recovery/air circulation either.

Background:
Flat roof has been on and windows fitted since the end of December. The capping/flashing on the roof has only been fitted the last 6 weeks or so and i think that due to the flashing not having been fitted when the roof covering (trocal) was fitted that this allowed water to come in and get soaked in to the walls - i feel that the walls may not have been dry enough to have been plastered, but were plastered anyway and that the result is the mould build up.

This may not be enough information for anyone to give their opinion but i would welcome hearing back from building related professionals on here, if you have ever come across a similar issue.

Thanks

Still waters

It's normal, it will go once you have the heat on, you or the painter may need to wash it off before painting


Walls need to be wet before plastering as damp walls are better for plastering onto , they should be allowed to dry naturally, so that closes that avenue of trying to blame builder/plasterer for the mould

Bonzo Delaney

Happening a bit with airtight houses during the build
Water vapour can't escape . Every door and window should be left open to allow as much natural ventilation as possible. But then you have the security issue when there's no one on site

smokey20

Thanks for the responses

I look forward to the electricity being switched on within the next 3 weeks hopefully and in the meantime i will have the windows and doors opened as much as possible.

Still waters, you mention that walls need to be wet befor plastering - i should have mentioned that the vast majority of the walls are slabbed, there is very little internal walls that aren’t slabbed

s8n

it happens

Still waters

smokey20 wrote: »

Thanks for the responses

I look forward to the electricity being switched on within the next 3 weeks hopefully and in the meantime i will have the windows and doors opened as much as possible.

Still waters, you mention that walls need to be wet befor plastering - i should have mentioned that the vast majority of the walls are slabbed, there is very little internal walls that aren’t slabbed

Either way it shouldn't be a problem, mould is more common recently due to newer building systems like airtightness and increased insulation

Wartburg

I´m surprised of hearing comments like "common", "no issue" and similar. I know myself that mould in new builds is pretty obvious here in Ireland but there are so many different types of mould and just a very small amount is harmless like edible mould.
The best practise is, to prevent as much mould as possible, by keeping the building ventilated during the construction stage. Especially the plasterers should learn how to ventilate the dampness out of the building, they bring in with every trowel of plaster.
If you have mould grown already, please clean all affected areas properly and never with a dry cloth or brush, to prevent a further spread of the mould spores.
For some cases I´d highly recommend to take a sample of the mould, to get it identified in a specialised laboratory. Some mould can cause serious health issues even years after.

paud100

Hi Smokey20. I have exact same issue now. Took about 3 months to get heating on after plastering and have this mould now also. Heating is on now but wondering how you dealt with it or did it cause any issues in the long run? Thanks.