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Black Mould / Damp - Plasterboard.

(19 Posts)
GlitteryLipgloss Thu 18-Dec-14 13:33:31

Moved into our new build Dec 13.

The upstairs bathroom (no window) has developed black mould on the top of the wall where it meets the ceiling on the plasterboard.

Am I ok to scratch the mould off - don't want to rub it into the plasterboard - and toothbrush some mould killer on...and then paint over - or do we need to do some more serious work on it (as in replace the plasterboard)


specialsubject Thu 18-Dec-14 15:31:23

you've been in a brand new house five days and it has mould??

I'd give the builder a call! The bathroom must have a ventilation system - does it work?

CheeseBadger Thu 18-Dec-14 15:34:10

Can you describe the mould or upload a picture?

If it's just speckled mould then it's almost certainly caused by condensation. Quite likely if there's no ventilation. It'll respond quite well to being scrubbed with bleach and water, left to dry, and then painted over. It'll come back if you don't sort out some ventilation though. Could you leave the door open after showering?

If the board feels a bit soft, you may have penetrating damp. Check the condition of gutters above that part of the house if so.

GlitteryLipgloss Thu 18-Dec-14 15:35:51

Sorry - Dec 2013 we moved in. It does have a ceiling ventilator thingy which does work when the light is switched on.

I've left the light on during the day whilst I am at work to try and dry it out.

And left the bedroom 2 window open at night - but shut our bedroom door - to try and dry it out more.

I've don't want to leave this, but not sure what's the best action to take.

GlitteryLipgloss Thu 18-Dec-14 15:39:34

Thank you Cheesebadger.

It's black and speckled. It has a large damp patch surrounding it all.

It's no where near gutters, our house layout means that the bathroom is between the bedrooms so not at the back or front of the house. Hope that makes sense.

Our house builder is sending a customer care manager around tomorrow to take a look - but I don't know much about damp. So don't want to be told rubbish.

CheeseBadger Thu 18-Dec-14 15:39:59

Glad to hear it's not just falling down Victorian ruins that suffer from this. You could get the fan put on a timer so that it stays on five or ten minutes after the light goes off. If it's taken a year for the mould to appear (and you don't think it's caused by penetrating damp) then you might have almost enough ventilation, and the extra few minutes might be enough to keep it at bay.

CheeseBadger Thu 18-Dec-14 15:41:15

OK. The large damp patch is more worrying than the mould. Is the plasterboard unpainted and unskimmed? I wouldn't normally expect condensation to produce visibly wet patches...

wowfudge Thu 18-Dec-14 16:11:08

Is there a valley in the roof above the affected bathroom wall or any lead flashing in that area or are there any ridge tiles directly above? It's possible something has shifted and rainwater is coming in. If it has been windy, have any roof tile or slates moved/slipped? Can you access the loft space above and look for any signs of water ingress above the bathroom?

Do you know if there are any pipes behind the plasterboard or in the ceiling above? Something might be leaking.

GlitteryLipgloss Thu 18-Dec-14 16:29:48

Thank you all for replying.

Husband has been up in the loft and hasn't noticed anything untoward. Although even if there was anything he wouldn't know what to look for - we are both DIY Novices.

I will have a look outside tomorrow and see if I can spot anything. Will also ask my dad to come over and have a look.

That's what is worrying me, if there is something above/behind the plasterboard as the damp patch is considerably large.

Walls/ceiling had been white washed/roughly painted white.

Am looking at bathroom paint now.

Joys of being a home owner eh.

CheeseBadger Thu 18-Dec-14 17:19:56

Wow is right. I think with a "large damp patch" you need to be looking for where the water might be getting in. That's sounding less and less like condensation, and more like penetrating damp. A photo might help...

What confuses me though is that you describe it as plaster board. I'd expect wet plaster board to bend or warp in some way eventually, and you don't say that it has. Hopefully tomorrow's visit will be instructive.

specialsubject Thu 18-Dec-14 17:50:29

ah, I see - 12 months not five days. Still not ideal!

This does shout 'building problem'. Glad that the builders are coming for a look.

TeddyBee Thu 18-Dec-14 18:28:11

Sounds like a roof issue to me, rather than condensation. We got similar in our extension thanks to a stupidly placed down pipe soaking our roof tiles. Tiles were fine, just overwhelmed by the water gushing over them from the down pipe.

PainterDecorator Fri 19-Dec-14 11:32:27

Clean moldy areas with a mild bleach solution rather than proprietary fungicidal washes (some of them are very toxic) Make sure ventilation is adequate, windows or vents should help keep moisture at correct levels, damp causes most mold so make sure your outside walls aren't getting and staying too wet, check gutters etc. use paint containing silver ion anti mold ingredient when decorating, this prevents mold spores from reproducing, and is completely safe, to keep paint costs down, you can add your own anti mold paint additive such as Silver Shield anti mold paint additive to own brand paints, avoid the fungicidal types as they can be toxic.

PigletInABlanketJohn Fri 19-Dec-14 12:06:46

You say it is a room with a shower and no window. So it is bound to have high humidity, condensation, damp and mould unless you take the water vapour away.

The fan fitted is most likely a cheap builders fan. You can get a ducted inline fan with three times the power, and quieter. In your position I would look for one that can be set to run at a continuous low trickle, and turn up to full power when the light goes on.

If the existing fan is connected to flexible convoluted hose it probably has water inside from condensation. This may be leaking. For a superior job, use rigid duct, sloping slightly downwards towards the eaves or point of exit, and flop loft insulation over it to prevent it getting cold.

A photo of your existing fan and duct would be interesting.

Happynapi Fri 19-Dec-14 14:36:34

Our fan drives us crazy as the wind catches it and makes a slight continuous flapping noise but it does stop mould from condensation building up in our windowless bathroom.
Just wish didnt have the noise on windy nights.

PigletInABlanketJohn Fri 19-Dec-14 16:37:00

if your old vent is the plastic venetian blind type, try a cowl vent next time the flaps blow off.

If you go to an inline ducted fan, you can have the draught shutters on the fan or in the duct away from the wind.

Happynapi Fri 19-Dec-14 23:46:06

Thanx PigletallwrappedupJ i wonder if the heavy usage would render it less effective with such a cover, also need firemans ladder to reach it and sadly so far I don't know any firemen or handy persons with very long ladder to call on.

PigletInABlanketJohn Sat 20-Dec-14 00:44:14

amenable windowcleaner or roofer

Happynapi Sun 21-Dec-14 00:34:48

Roofer! Brilliant idea and thanks for link too.

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