LocostBuilders - powered by XMB

Getting rid of mould in the loft

andrew-theasby - 23/1/10 at 09:26 PM

Bit of a strange question for on here but someone usually has the answers. Is there a product i can use to kill white mould on bare wood in my loft?
I currently rent my bungalow out, and during the cold spell had to pop over to do some work. Whilst in the loft, i noticed moisture all over the felt and the woodwork was damp. Nothing was really mouldy so i assumed it was fresh. I put it down to condensation as they keep the house very warm (new baby) and there wasnt much insulation. Ive been over and layed out a few bags of insulation since, and the south end is dry now. The north end still has moisture glisterning on the felt, and the wood is still wet. Theres a white mould growing on a lot of the wood at this end and i want to kill it as soon as it dries out, assuming ive cured the moisture. Any suggestions? Thanks.

andyharding - 23/1/10 at 09:33 PM

The product you want is called stopping the damp. No need for chemicals, will only grow back unless you cure the cause anyway.

zilspeed - 23/1/10 at 09:42 PM

Ventilate the attic space.

You can fit vent tiles or continuous eaves ventilation.

We see loads of dampness problems, and very very often it is our old friend condensation.

Unless you can see definitive signs of water ingress which is evidence of some sort of traumatic event, it is likely to be condensation.
Seeing moisture glistening on the underside of the roofing felt pretty much confirms this.

(In Scotland we would have sarking boards which ever so slightly helps this issue, but I digress.)

Ventilate the attic space.

***************

Forgot to add, depending on the severity of the mould growth, it may be necessary to kill it in addition to the ventilate issue which is definitely the seat of the problem.
Only you know what the mould looks like, so get some pics and then google it.

In cases of black mould we recommend washing down with a dilute mix of bleach in water (1:4 IIRC), but you don't have black mould so do some further investigation.

All of the above after addresing the ventilation issue.

[Edited on 23/1/10 by zilspeed]

blakep82 - 23/1/10 at 09:43 PM

quote:
Originally posted by zilspeed

(In Scotland we would have sarking boards which ever so slightly helps this issue, but I digress.)

ah, is that what they're for? all mine are falling off

andrew-theasby - 23/1/10 at 09:53 PM

i hope i have stopped it by insulating over the ceilings, its only had a few days to dry out now tho. I want to get rid of the mould when it does dry out. Wont the gaps around the tiles ventilate it enough? Its not a new house. Thanks.

zilspeed - 23/1/10 at 09:54 PM

quote:
Originally posted by blakep82

quote:
Originally posted by zilspeed

(In Scotland we would have sarking boards which ever so slightly helps this issue, but I digress.)

ah, is that what they're for? all mine are falling off

If they're falling off and the house was built in the 60s-70s, it will be fibreboard or celotex. Before that it was softwood. Nowadays we tend to use OSBII or sheathing ply.
I'm not saying their primary function is as thermal insulation, but you can't disregard them if doing a calculation for example, as they will make a difference.

Steve Hignett - 23/1/10 at 10:02 PM

Blake - you just cost me a Fiver!!!

zilspeed - 23/1/10 at 10:02 PM

quote:
Originally posted by andrew-theasby
i hope i have stopped it by insulating over the ceilings, its only had a few days to dry out now tho. I want to get rid of the mould when it does dry out. Wont the gaps around the tiles ventilate it enough? Its not a new house. Thanks.

Lifestyle issues can have a collossal effect on the dampness issues within a property.
Two identical house can be very different.
House A, heats the house to 21 degrees in the evening and in the morning. Heating goes off during the day and they open the windows to ventilate the place during the day.

House B, they heat the place to 27 degrees all of the time, never open the windows.
Consequently, there can be a build up of moisture (warm air is far better at retaining moisture than cold air) as the air moves in the direction of a colder zone, it will eventually cool enough until it gets to dew point. (The point at which it can no longer retain the moisture) and bingo, condensation.

In your case, with the tenants having a new born baby, it would not be remotely suprising to find that the place is like an oven with not a breath of ventilation.
The mositure will always find a place to either escape or condense.

One way or another, the house needs a level of ventilation commensurate with the level of moisture being created.

You need.

Either

A) More ventilation.
B)The tenants to modify their lifestyle.

- or -

C) Different tenants.

David Jenkins - 23/1/10 at 10:06 PM

My local builder earns a reasonable amount of cash ventilating lofts where people have previously blocked off all ventilation.

I used to have a flue going up to the top of the roof that became redundant when I changed my central heating. I asked about blocking it off, but he advised me just to put some mesh across the pipe to stop wasps etc and otherwise leave it open. I never get any condensation problems...

andrew-theasby - 23/1/10 at 10:27 PM

I know what your saying about lifestyle, last year i did the cavity wall insulation because the walls went mouldy, but i insisted then they ventilated it better, and it hasnt come back touch wood. Could the sudden lack of ventilation be caused by filling the cavity? Other than that, nothing has changed in the loft in the last 50 years other than the excess heat leaking through the ceiling, now cured hopefully.

mookaloid - 23/1/10 at 10:53 PM

How about an alternative solution?

http://www.envirovent.com/home/healthy_homes.php

Cheers

Mark

zilspeed - 23/1/10 at 10:58 PM

quote:
Originally posted by andrew-theasby
I know what your saying about lifestyle, last year i did the cavity wall insulation because the walls went mouldy, but i insisted then they ventilated it better, and it hasnt come back touch wood. Could the sudden lack of ventilation be caused by filling the cavity? Other than that, nothing has changed in the loft in the last 50 years other than the excess heat leaking through the ceiling, now cured hopefully.

You've filled the cavity, the house may well be less draughty than previously.
It's the same as taking draughty old timber windows out and replacing with gas tight upvc windows, you lose a bit of ventilation.
while wer'e on the subject, if the walls were mouldy as opposed to water stained with a definitive tidemark, chance are that was condensation too.
I'm not a fan of cavity fill, but we won't go into that now.

Going back to the loft, as I said previously, the loft may not have changed, but the lifestyle issues can impact very significantly.
In short, it's possibly not the house's fault.

If you use a protimeter on search mode, it will tell you if the moisture is in the fabric.
Used in measurement mode will confirm it being on the fabric.

See how you get on, I'm being a bore now.

zilspeed - 23/1/10 at 11:01 PM

quote:
Originally posted by mookaloid
How about an alternative solution?

http://www.envirovent.com/home/healthy_homes.php

Cheers

Mark

We occasionally fit a similar product called a flatmaster.
The problem is that because it costs money to run, there is a degree of control from the occupants.
They can turn it off...

andrew-theasby - 23/1/10 at 11:01 PM

the cavity wall people were pushing to sell them, but they were about Ł800 iirc Im hoping ive cured it now anyway, one end of the loft has dried out. might stick the dehumidifier up there for a bit?

mookaloid - 23/1/10 at 11:12 PM

quote:
Originally posted by zilspeed

quote:
Originally posted by mookaloid
How about an alternative solution?

http://www.envirovent.com/home/healthy_homes.php

Cheers

Mark

We occasionally fit a similar product called a flatmaster.
The problem is that because it costs money to run, there is a degree of control from the occupants.
They can turn it off...

We tell them that if the problem doesn't go away after we provided the means to cure it because they turn it off - then they are responsible and have to pay for any subsequent damage. Most of them are grateful that their house doesn't smell mouldy any more.

andrew-theasby - 23/1/10 at 11:21 PM

quote:
Originally posted by zilspeed
See how you get on, I'm being a bore now.

Not at all, i appreciate all the comments, but i dont think i have that equipment, unless you mean using a multimeter? Im mainly worried about how the mould has appeared in a week, since we noticed the damp, purely coincedence we were even up there luckily! I like the idea of the vents though, would they go in the fascia boards or the bricks?

blakep82 - 23/1/10 at 11:50 PM
quote:
Originally posted by Steve Hignett
Blake - you just cost me a Fiver!!!

sorry, i'll get get it sent by paypal...
er, how did that happen? lol

zilspeed - 23/1/10 at 11:56 PM
quote:
Originally posted by andrew-theasby
quote:
Originally posted by zilspeed
See how you get on, I'm being a bore now.

Not at all, i appreciate all the comments, but i dont think i have that equipment, unless you mean using a multimeter? Im mainly worried about how the mould has appeared in a week, since we noticed the damp, purely coincedence we were even up there luckily! I like the idea of the vents though, would they go in the fascia boards or the bricks?

Eaves ventilation generally goes in the soffits. Ideally on opposing sides so you get cross ventilation.

[Edited on 23/1/10 by zilspeed]

JoelP - 25/1/10 at 10:58 PM
i feel the need to mention that insulating the loft will cause MORE condensation, because it will be colder up there. If there was no insulation at all then the loft would be a similar temp to the house and no condensation would happen.

Make sure there are no obvious routes for warm moist air to get up to the loft, ie round pipes etc.

Liam - 26/1/10 at 01:25 PM
quote:
Originally posted by JoelP
Make sure there are no obvious routes for warm moist air to get up to the loft, ie round pipes etc.

Or holes punctured in bathroom ceilings for downlights.

If this has only happenned now during the snow it could perhaps be a freak occurence due to that. I used to have my bedroom in a converted pre-fab garage with a very shallow pitch to the roof. No leakage or damp problems at all except on the two occasions where heavy snowfall resulted in inches of snow sitting on the roof for days/weeks. This meant a constant reservoir of water was sitting on the roof slowly melting and finding the smallest gaps to gradually seep through, and resulted in some damp penetrating into the room. Never happened without snow sitting up there, even in the heaviest rainfall.

If your loft is well ventilated and you aren't obviously pumping warm moist air up there, this may have been the problem. Water sitting up there long enough could feasably find gaps/seams in the felt under the tiles, or even slowly seep through it if its old/crap.

Just my 2p, but you do need to check out the ventilation/moisture aspect. As said the extra insulation probably won't have helped in that regard, but was worth doing anyway from a heating bill point of view.

Liam

[Edited on 26/1/10 by Liam]

andrew-theasby - 26/1/10 at 09:54 PM
I dont think theres any holes anywhere, i think it must be just combination of the snow sitting on the roof and poor ventilation. Not so sure about no insulation meaning no condensation? Surely that would be worse, the warm air against the cold tiles/felt would condense more, like it does on your windows. I guess when theres no snow on the roof therell be a bit of a draft through the tiles and felt.