Mould/condensation on upstairs ceilings.

[Sharpey]

Hi all.

I want to have the upstairs ceilings plastered as they have an artex on them at the moment. In two rooms though, where the ceilings meet the outside wall, black mould patches appear. obviously this needs to be fixed before the plastering otherwise it will just come back

In the other two rooms, mould hasn't appeared yet but I think that is due to them being used far less. The edges in those rooms are cold as well in comparison to the rest of the ceiling.

My thinking is that the insulation in the loft is not covering these mouldy areas adequately or at all. This is causing the cold patch on the ceiling leading to the mould. Unfortunately, because of the restrictions in the loft space (no boarding, old air heating pipes running throughout, angled/low roof, beams etc) it is very difficult to get up there and have a proper look.

The loft, at a glance, seems badly insulated in general but seems to do it's job in the main. There is also a 'shadow' effect on the ceiling in straight lines, presumably where the joists are situated in the loft, but I am hoping the re-plastering will help hide these.

Does anyone have any advice on how to proceed? There are wood panels above each door in the bedrooms, which I was thinking of venting to improve airflow in the room and perhaps stop the condensation from forming in those mouldy areas?

Appreciate any help, regards.

 

[Chri5]

Mould on the ceiling to outside wall edges could be failed guttering.

Now in the loft, get rid of all the rubbish old stuff that you say is surplus and out with the touch / lead lamp.

Is anything wet or damp up there from rubbish flashings, a slipped tile or an under vented area due to insulation being stuffed everywhere and no drafts?

Do you have an roof tile vents, and if so have those been kept clear of the insulation?

Have you read the first post on these forum about condensation?

Do you have unvented bathrooms, use a clothes drier or regularly use the ch as drying points for the clothes wash?

 

[Sharpey]

Thanks for the reply Chri5.

The room that is the worst for the mould used to have a dehumidifer in it when I first moved in, and it's the room that gets used the most. So it is likely a lack of ventilation?

I have been up in the loft today and managed (just about) to get a look at what is above this room. The other rooms bar maybe one (there are 5 in total) would be very difficult to get to. As far as I can tell, there is no block to the vents, which are situated around the edge of the house, think they're called eaves? Here is a picture, which doesn't show it well, but there is a big gap between that wood at the back the foremost edge. So I don't think it is a draught issue.

Untitled

• Sharpey
• 8 Jan 2013
• 1

As you can see though, between the edge of the wall and insulation, the plasterboard is bare. I saw this in the few places I could get access to. I also saw a big un-insulated patch where the biggest mould patch is on one of the ceilings here:

Untitled

• Sharpey
• 8 Jan 2013
• 1

Ignore the pin, that was put there by me so I knew where to look when up there. That picture doesn't fully show it but that whole area behind the air heating pipe is not insulated and that is where it is mouldy. You can see though that area is not insulated

As for your queries. I have read the condensation sticky. Apart from not opening windows as much as I should, I don't think any of it applies here.

Don't dry clothes upstairs or use radiators for it. Bathroom has window regularly opened and extractor fan turns on with light. I couldn't see any evidence of leaks/damp in the loft, there was no wood rot from what I could see, nothing appeared damp. It seemed dry.

What do you think? I'm far from an expert, but I think the draught that enters the loft around the edges hits the plasterboard that is not insulated, making that part of the bedroom ceiling cold which is where the air condenses causing the mould? It seems to make sense.

 

[Sharpey]

Hello again.

Just to follow up on this, can anyone suggest an alternative fix than to sort out the insulation in the loft?

I've just been up there but it's practically impossible to get access to the areas that need attention.

I am having the ceilings plastered on Thursday so in the future I want to avoid the build up of condensation/mould on these cold areas.

Is more ventilation or installing a dehumidifier my only options?

 

[JohnD]

I have read the condensation sticky. Apart from not opening windows as much as I should, I don't think any of it applies here.

Don't dry clothes upstairs or use radiators for it.

water vapour is lighter than air so it rises up through the house until either something stops it and it turns to condensation, or it escapes for example through an open window.

open the windows every day for a week, and send me a pound if the damp patch gets better.

 

[deniance]

it could be that the areas arent insulated causing cold spots underneath, then condensation, or it could be the draughts coming up through the eaves in your pictures are cooling and wicking away the heat from the ends of the insulation, i would stick a plastic bag over the ends of each roll of insulation like a sock to stop this, black bags are cheap and it may magically solve your problem, worth a shot, ive seen this problem in a few houses where by use of a thermal camera shows a fully insulated attic right up to the eaves, can have a cold perimeter because the eaves ventilation is stripping the heat from the ends of the insulation, let us know how you get on

 

[Sharpey]

Thanks for the replies guys.

I am certain it's the insulation. The outline of the mould is exactly the same as the bits that aren't insulated. However, it's impossible to fix this because I just can't get in to the tight spaces where there is no insulation.

How often should I open the windows? How do I know how long to keep them open?

Would a hygrometer be useful here?

 

[deniance]

Could you not get some loose fill insulation and toss it in or brush it in, hygrometers are very handy, ebay- hygrometer - cheapest first- solar powered digital about 4 quid, gives digital temp and humidity, no batterys and works brill I've got 3, bedroom bathroom and downstairs, I have so much humidity its silly, mould everywhere, it should be 35 to 50 percent and I'm in the 70s upstairs and 60 downstairs, emptied another 2 litres from my dehumidifier just now!

 

[Sharpey]

Nah loose fill is out as well. It's a combination of beams, no boarding, old HVAC system pipes and the slanted roof making it impossible. I could get some insulation in there with great difficulty but there would be no control over how it was placed and it could just as easily block the eaves. Plus I can't breathe up there either, which is important!

So could a hygrometer basically tell me when I need start opening windows and when I'm safe to close them? They're not that expensive so if something that simple could help me I will definitely look in to it.