Widespread white mould in loft. More ventilation or insulation needed?

[Angela Qian]

We have a sorted of converted loft space, which is carpeted, have plasterboard ceiling and a narrow staircase from first floor. After moved in 2 months ago, we noticed in the last 2-3 weekend that there are a lot white mould on the front ( north facing) and side of the ceiling, and it is definitely getting worse. Nothing at the south facing back side ceiling.

Got two roofers in, the first one said there is no insulation at all in between the roof and ceiling, and the ice on the tiles get into the ceiling and make them damp. So the solution is to insulate the whole ceiling which takes 2-3 days and I think will be relatively costly. There are two vents at the front that were installed not long time ago but he said that doesn't make any difference.

The second said it is because there is not enough ventilation. So need to install two more at the side, so that air can circulate. That will cost £200. I asked about insulation he said that's not the main reason.

I think the second one makes more sense. But just want to double check if anyone in the know thinks the same?

And at the mean time, would open the skylight help before a proper fix is done? What about the mould, can I wipe them down with damp cloth or anything?

Any advice is greatly appreciated.

Thanks

 

[footprints]

If it is any help I insulated my loft over the extension and got white mould forming I cleaned it off (used a vacuum cleaner with a hepa filter and wore a mask not sure if that was right but I am still here) increased ventilation and also fitted draught excluder to the loft hatch as it is next to the en-suite so might have been getting steam when the door was open.
The mould has stopped now.

 

[Angela Qian]

If it is any help I insulated my loft over the extension and got white mould forming I cleaned it off (used a vacuum cleaner with a hepa filter and wore a mask not sure if that was right but I am still here) increased ventilation and also fitted draught excluder to the loft hatch as it is next to the en-suite so might have been getting steam when the door was open.
The mould has stopped now.

Ventilation sounds like the way to go. Thanks

 

[vinn]

Difficult to know exactly what you've got in terms of the structure - why not post pics?

Warm moist air from the rooms below the loft is penetrating into the loft and hitting the cold surfaces where it condenses - there's a mass of previous info about this on here if you wanted to look?

When you say you have "a sort of converted loft space" - is the loft correctly insulated and passed BCO for a conversion?

 

[Angela Qian]

Took a while for me to figure out how to add the pictures. Hopefully you are able to see it as I do. And please ignore the mess.

The loft is plasterboarded, the floor is boarded and carpeted, with a narrow fixed staircase leading from the 1st floor landing - there is a door at the lower end of the stairs. There is no insulation between the felt and ceiling plasterboard, not sure about the between the joints but I guess the board and the carpet works as some kind of insulation? And No it is not a proper conversion. It is done without planning permission or building regulation by the previous previous owner at least 15-20 years ago, and we use it as storage only.

We have kept the skylight open until lunch time today, the reading on the humidity meter is 57%, sounds great. But at around 6pm, it rises to 93%. I will keep an close eye on the reading in the next couple of days but this is quite worrying...

I have read a lot of info on the forum and also other websites. But most of them is for loft with insulation, while ours doesn't have insulation, but it does have non breathable felt, and I guess the plasterboard stops the air from going out as well? If so would that mean we need some kind of ventilation inside the loft space, not just tile vent that is between the plasterboard and the roof?

I'm so confused.....

Difficult to know exactly what you've got in terms of the structure - why not post pics?

Warm moist air from the rooms below the loft is penetrating into the loft and hitting the cold surfaces where it condenses - there's a mass of previous info about this on here if you wanted to look?

When you say you have "a sort of converted loft space" - is the loft correctly insulated and passed BCO for a conversion?

 

[vinn]

Without seeing behind the plaster boarding its difficult to impossible to say much about whats happening
below the tiles or slates - I suppose you have an access hatch to get behind the framed walls and could post a pic of the rafter area?

An educated guess based on experience can only take one so far - here there are a number of variables to take into account, not least the lack of BCO certification. Plus: any signs of leaks or excessive condensation around the skylight - is there a door to the room, do you keep it open or shut - is there any heat in the room?

That condensation appears to be older than two months or less - how come your mortgage surveyor didn't pick this up in his report?
Are you certain that the seller was not flipping the house on the basis of a limited makeover?

Others on here have more experience with condensation than me, perhaps they will pick up your thread?