Hi,

I have a bungalow built in 1950s with a suspended floor and a pitched roof
extension. The extension measures 12ft x 15ft and is heated by a 2ft x
2.5ft single radiator (inadequate, I know). Since moving in 9 months ago, I
have noticed mould growing on curtains / carpet etc particularly in the
extension. The extension is noticably colder than the rest of the bungalow
even though it's directly off the lounge. I pulled the carpet up today and
found that there was white mould (smells mushroom-like) underneath the
underlay on the chipboard flooring - it feels damp. I removed a piece of
the flooring and got a good draught so the air bricks must be Ok. It's just
chipboard flooring - no insulation of any kind. The original part of the
lounge has floorboards and does not feel damp.

What do you reckon - is it a ventilation problem? Should I take up the
chipboard and lay floorboards and hope that improves things? Or does the
floor need insulating - how would I go about doing this? Could condensation
have built up in the chipboard due to inadequate heating?

Any advice greatly appreciated!

Graham.

In an earlier contribution to this discussion,
Graham wrote:

Hi,

I have a bungalow built in 1950s with a suspended floor and a pitched
roof extension. The extension measures 12ft x 15ft and is heated by
a 2ft x
2.5ft single radiator (inadequate, I know). Since moving in 9 months
ago, I have noticed mould growing on curtains / carpet etc
particularly in the extension. The extension is noticably colder
than the rest of the bungalow even though it's directly off the
lounge. I pulled the carpet up today and found that there was white
mould (smells mushroom-like) underneath the underlay on the chipboard
flooring - it feels damp. I removed a piece of the flooring and got
a good draught so the air bricks must be Ok. It's just chipboard
flooring - no insulation of any kind. The original part of the
lounge has floorboards and does not feel damp.

What do you reckon - is it a ventilation problem? Should I take up
the chipboard and lay floorboards and hope that improves things? Or
does the floor need insulating - how would I go about doing this?
Could condensation have built up in the chipboard due to inadequate
heating?

Any advice greatly appreciated!

Graham.

Are the joists wet? What is supporting them? Is it possible that there's a
sleeper wall under the joists which doesn't have a proper DPC?
--
Cheers,
Set Square
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"Set Square" wrote in message
...

Are the joists wet? What is supporting them? Is it possible that there's a
sleeper wall under the joists which doesn't have a proper DPC?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.



You are spot on! The joists are wet and they do appear to be supported on a
sleeper wall. How should I damp proof this? Can I lay a damp proof
membrane directly under the joists?

Thanks,

Graham.

It is unlikely that your mouldy curtains, or indeed the majority of
symtoms you are suffering in the room are the result of anything other
than condensation.

Which elevation is the extension on - North, North East? or is it in a
particularly windy environment?

Also, being built in the fifties, It will have dreadful u values in the
walls and floor which aren't going to help.

Heat it better, ventilate it better (does it have PVCu double
glazing?), generally follow all good guidelines to combat condensation
and your mould will disappear.

If you do indeed have wet joists this could be caused by a lack of damp
proofing on the sleeper wall, as SS suggests. Howver, if this is so,
it's an error on the builder's part and, to be honest, if you've had
wet joists sincer 1950, you're very lucky you haven't got any kind of
rot. You should check on top of the sleeper walls for a black
substance between the brickwork and the timber, probably plastic but
maybe bituminous which is acting as a dpc. If you can't see it, the
sleeper walls may be built directly off the oversite and they've put a
dpm beneath that.

If you really haven't got any form of dpc then you're going to have to
slightly jack up east joist (quarter of an inch or so) in the vicinity
of the sleeper wall and slip a piece of dpc between the wall and the
joist - no big deal. To be honest, this is unlikely, it's more likely
to be sub-floor condensation.

If you can hire (beg, borrow,steal) an electronic damp meter, your
joists should have a mosture content of less than 22%. Ideally it
should be less than 20% but sub floors are never ideal places and
they're usually on the high side. Don't use it on the walls, you'll
frighten yourself with the levels of condensation you obviously have

If you want any more info on condensation, email me directly and I'll
give you the url of my website.

HTH

Xav

Have alook and post back

Your joists should be sitting on your dpc and the air bricks should be
between the joists so that air circulates around them.

As for the mush, it may be a reaction from the adhesive in the
chipboard or carpet underlay. Try folding the carpet back, airing the
room and look again in a day or so.

A logical approach to this might help you. Moisture can either rise
from the ground or penetrate via a structure such as a wall which has
moisture on the other side of it. From what you say, your's could
possibly be rising but the chances are it isn't and that the dpc (such
as it is) is working. The only other kind of moisture available other
than plumbing leaks or rainwater is that which soaks into materials
from the atmosphere, - hygroscopic.

Rule them out one by one and you'll be left with your cause. From what
you say it's the latter kind, i.e. condensation. This is evidenced by
the mould in the room itself and the conditions you describe.

What is the sub floor base made out of (beneath the floor), is it just
earth or is there a concrete screed over it? Also, does the
ventilation cover the whole floor or is it windy just in one place?.
Also to check, is it just ventilated when the wind is in a certain
direction or is it constant?

I can't see it being anything other than condensation but that's not to
say you shouldn't be concerned. Condensation is the number one cause
of dampness I see and it can be very destructive.

However, you need to check the moisture content of your joists before I
can advise you further because what might seem wet to you could be dry
as far as fungal activity is concerned. If that's the case, all we
have to cure are the problems in the room itself.

Sorry if this is disjointed, bit late in the day, been up since four
o'clock. If you're still worried tomorrow, give me a ring and I'll go
through it with you on the phone.

xav