Damp in loft conversion - newish house

[jasonlhill]

Assuming it's a pretty conventional developer house the membrane would (should) be a breathable one and as such cross ventilation is not required, at least that's the theory. Generally they work fine however I would look to see if there is moisture getting into the unconverted loft space exacerbating the issue. Just how much mould are we talking about here? If that's a dead end then you'll have to add additional ventilation, there are various ways to achieve this. The converted space requires some background ventilation if there is none.

It looks like what they've done is actually built it within the existing pre-manufactured trusses, hence the odd space.

Not had mould problems since I discovered it back in January (been here since December) - it was on suitcases and anything material based, these were stored in the loft room - anything placed in the unconverted areas was fine. As mentioned by someone else, it will be the lack of ventilation in the converted loft room....

Strangely though the room is carpeted, there has been no mould or even feeling of damp to the carpet - which seems odd

 

[jasonlhill]

....and, how do you access that loft space? A proper stair, a loft ladder, or some other means?

Is there a hatch, which could be left normally closed, to prevent the rising moist air entering the space? Then add some ventilation up there, which might help solve your problem.

Yes access is by pull down ladder through a loft hatch - it's to the left of the images above and gives access to 2 of the unconverted arears.

 

[jasonlhill]

Mine is similar, just a bit of an electronics work space, but I fitted a Velux. My rule is to always have the hatch closed in cold weather, but the Velux vent remains open year round. No damp or mould here.

I had considered this, but with the shape of this 'room' I cant imagine how that would work without removing the walls

 

[Harry Bloomfield]

I had considered this, but with the shape of this 'room' I cant imagine how that would work without removing the walls

Just to repeat - you need to find some way to add ventilation. Even a 6" extract through a wall to the outside, will help considerably, when the level of moisture rises up there. Combine that with sealing the access, when not actually in use.

 

[JohnD]

Are there holes in the ceilings below, for example for downlighters?

Is wet washing ever draped inside the home?

 

[Koolpc]

Ventilation is the key thing here.

I wouldnt fancy carpet up there though.