2 Oct 2007
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United Kingdom


Before I ask my question I need to explain what happened previously.

Exactly a year ago while I was in hospital for major surgery my wife and daughter had my
ensuite completely ripped out, because they were worried that my wound would get infected.

This is because my ensuite suffered with a serious black mold problem that seems to be in the
fabric of the whole room. No matter how much cleaning with raw bleach I did it always came back.
This didn't seem to be regular mold and it attacked most everything especially the ceiling and
shower area.

The original property has solid concrete floors, but an added rear extension also has concrete floors
but for some reason (probably to save money) the extension that is a bedroom and ensuite is
suspended on green water "resistant" chipboard.

There is a gap/space of around 4 inches between the chipboard and the concrete floor below.

Over the past few years the skirting board (thick Torus type) in the ensuite had become bent
and twisted and moved away from solid internal block walls - I've never seen wood do this before.

The chipboard floor had also disintegrated in places so I had to tread carefully.

The whole room was disgusting and a total embarrassment. No matter how much this room was
cleaned it always came back with a vengeance. The bedroom that is only separated by a door
doesn't have a problem,

Some years ago I discovered a leak when I pulled out the main bathroom. A pipe connection
behind a plasterboard wall must have been dripping for years. It had been seeping under an
internal solid wall and leaking into the gap under the ensuite floor.

I ripped everything out, put in new timbers, retiled etc. Checked everywhere and found no
more leaks.

But for some reason it seems this problem has taken hold.

The guys that came in to do the bathroom as I said ripped everything out, laid down Aqua-Board
on the floor and tiled on top (so the gap would still be there). They made an excellent job of the
shower area by cutting floor below and made the shower tray flush to the floor. They also fitted
green moisture resistant plasterboard to the ceiling.

But because I was due home they run out of time and didn't manage to finish of the room,
especially plastering and painting the green plasterboard.

Due to the surgery (small bowel) I had to use the en-suite for many hours every day for many
months (with less than 30 seconds warning), so the blokes who did the work couldn't come back
to finish off for a long time.

As time went on I found problems with a lot of what they had done and decided not to get them back.

When I'm fit enough I'll finish it off myself.


The plumber replaced the old fan with an expensive powerful inline extractor fan that I'd brought a
few years ago ready to do this room. I can't remember how much air this unit replaces per minute but
it is definitely much more than my small ensuite requires.

When I look through the grill to the white flexi pipe connected to the fan I can see that it has turned black.
Also the solid resin shower tray and white sealant unfortunately started to turn black about 6 moths ago.

Clutching at straws but I'm beginning to think the mold spores are actually in the cold water pipe feeding
the shower. I say cold pipe because until 4 years ago I had an electric shower. The shower now comes
off the boiler.

Around a week ago I noticed the "green plasterboard" on the ceiling (the walls & ceiling are tiled) have just
started to change colour about 10 inches from some of the edges.

Just a slight 'mottled' brown colour. It might be down to the cold weather, but there is a working radiator in

I'm concerned that this might be the start of mold.

Pheew! Sorry for all that, but I did need to explain before my short question.


Will it be okay to apply PVA diluted 5 to 1 to green plasterboard?

This should seal it until I can plaster and paint it - hopefully middle of January.

SO - would it cause a problem if I use PVA on the paper surface?

I've used PVA on dusty walls and such before, but I'm not sure about plasterboard and I don't want to mess up
at this stage.

Finally if anyone has any thoughts about persistent mold I'm all ears.

Thank you in advance

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To start with pva will not be any good to seal your "moisture" resistant p/board and also your plaster board wont be w/proof neither will your "green "chip board!!! It will resist "damp "for a while then it will just fall apart. Believe me..As for your black mould it is caused by damp air and condensation .By the sound of it your shower/bathroom has not been professionally done. There are a lot of things that need sorting out..You need to get a recommended good tiler in. One who will explain about backer board and tanking systems and good quality materials. ie Dow-Corning silicon, good branded adhesive, and good branded grout. Black mould will rear its ugly head whenever it is given the right conditions for it to do so.So it is up to the person doing the work to use like l said good quality materials and advise you of what you need to do (wipe excess water off tiles off with a squeegy when getting out of shower or around tiled bath areas) A 2 minute job that can save a lot of grief!, Also get a good extraction system to give you a good airflow in your shower and bathroom. I am sorry to hear of your illness and hope this helps you out.?
Sorry to hear about your woes with regard to the dreaded damp. You've probably found out the hard way that you can seal everything a thousand times, but if the actual construction of a building isn't right, you'll never solve a resident damp issue. It really is all about the roof, the walls, the DPM... and most importantly, VENTILATION.
Really hope you got it all sorted!

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