I've got a 6ft wide by4 ft deep alcove in my bedroom.
For the last two quarters I've removed ceiling mould
with Dettox mildew and mould remover and repainted.
Now it's back again:
I've scanned previous postings and the advice has been
ventilate. I can't leave a window open as anyone could
climb on my garage and get to the window. The window
is double glazed so I'm loath to put anything through it.
I've drilled large holes in the top of the frame and put
a cover over it.
Is there a way to put anything through the ceiling
into the loft and out under the eaves?
You are sure this is from inside, not a small leak from outside?
You could potentially put ducting through and out at the eaves, with
maybe a small extractor fan, if there is enough space (if this is a bay
with a roof over maybe not)
But more to the point, think about the source of the problem. The main
sources of moisture (other than people) in the home are the bathroom and
the kitchen. Do you have adequate ventilation in those areas?
window fan (hole in glass, butt ugly)
wall mounted fan (big hole in wall)
vent through ceiling into loft ducting to outside
a window lock that will lock it in the 1/4" - 1/2" open position.
a dehumidifier has some advantages though. Hassle free to install,
similar run costs, no heat loss, and can be used for this:
That isn't condensation, it's penetrating damp - probably a small drip,
which has soaked the ceiling material, whether it be plasterboard or lath
and plaster, and the mildew you are seeing is a result of that - a wet
ceiling can take weeks or even months to dry out once the leak is sealed,
but your priority must be to seal this portion of the roof - luckilly it
looks fairly close to the guttering (which could also be the cause of the
leak), either way it could be sealed up with any roof sealant, but OTOH, the
leak could be further up the roof and the drip is rolling down the inside of
the roofing material and saoking into the insulation where it's cramped in
the eaves - first port of call is the loft, preferably when it's raining and
take a hefty torch - if you pinpoint the leak, you can take measurements and
make it easier to locate once you are on the roof.
Ventilation is one of the keys, but insulation is the other in that if
the water vapour in the air, from presumably the kitchen/bathroom,
meets something that is cold enough for it to condense on, then you
will in due course get mould. Even if you ventilate well in the
affected area, you've still got cold surfaces, so either eliminate the
source of the water vapour before it gets to the bedroom or make the
All my mould areas disappeared, and we had many, when I stripped off
the old lathe and plaster lining, put in insulation, dpm, and relined
with ordinary p/b.
I would check first that you don't have a leak in the roof above - can
you get to that corner of the eaves and see if the rafters are wet?
Assuming it's condensation, first consider where the moist air is
coming from. Does your bathroom have an extractor fan? Do you keep the
door shut when using the bathroom?
If all that is accounted for, and you need to provide ventilation in
the bedroom (sleeping people, breathing, put a lot of moisture into
the air), I'd get a builder to fit a large air brick in the wall, and
cover the inside with a hit-and-miss vent (the type of grille that can
be opened and closed).
Finally, decent loft insulation will make the ceiling less cold, and
water vapour less likely to condense on it.
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