Black mould in loft of house I’m purchasing - drimaster causing issues?

MeandO

The survey on a house I am purchasing has come back with black mould on the underside of the white felt and on the wooden rafters in the attic. The house also has a drimaster system fitted with the warm air being pushed out into the loft. The surveyor has said this could be the cause of the problem, with extra ventilation needed in the loft space. 

Does anyone have any knowledge or experience of this please and could offer any advice? I can get extra vents etc added but would I need to get rid of all the mould stained felt too and scrub the mould off the rafters or is that a job for professionals?
I’m concerned as to the health implications of the mould for myself and my child if I do proceed with the sale and whether to proceed at all really. 

Many thanks 

anselld

AFAIK Drimaster is a positive input ventilation system.  It should be drawing air from the loft and pushing it into the house, not the other way round.  If it is the heat exchanger type then external input and output should be outside, not in the loft.   If it is indeed blowing warm air into the loft then it is incorrectly installed.
Loft should in any case be ventilated at the eaves and/or elsewhere.

missile

I would walk away

tacpot12

missile said:

I would walk away

I don't think there is any great problem here, unless the Drimaster was installed by the home owner. If the Drimaster is pumping warm air from the house to the loft, the homeowner has wired it in backwards, or the unit was assembled incorrectly by the Numaster - a professional installer would have noticed either of these errors straight away. If the home owner has botched a Drimaster install, what else have they botched? Definitely a red flag for a closer examination of the electrical installation, but no reason to walk away just yet. 

If the Drimaster is wired correctly, the mould is being cause by water ingress, the source of which needs to be identified, ideally prior to purchase. 

MeandO

Thank you all. There doesn’t appear to be much in the form of ventilation in the loft so the survey has said extra ventilation needs to be installed which I can get sorted, but it’s just the mould that is concerning me really. It’s not what I’d call horrendous, but is on the underside of the 3 year old roof felt and some rafters. Would I have to get this professionally removed?

 

anselld

There is no particular need to remove the mould.  It is not as if you will be living in the loft. 
You just need to address the root cause of why it is there in the first place.

fewcloudy

MeandO said:

Thank you all. There doesn’t appear to be much in the form of ventilation in the loft so the survey has said extra ventilation needs to be installed which I can get sorted, but it’s just the mould that is concerning me really. It’s not what I’d call horrendous, but is on the underside of the 3 year old roof felt and some rafters. Would I have to get this professionally removed?

 

Although it is unsightly, I would expect that once the loft ventilation issues were dealt with i.e. improved ventilation, the mould would stop growing immediately.  It is usually easy to remove, and as the current "ideal-mould-growing-conditions" will change, it should not return.

tacpot12

Agree with all the above, the mould will go when the conditions are changed to be less favourable to mould. If you want it cleaning, a quick spray with HG Mould Cleaner will remove it. Given the size of most roofs, you might want to pay a someone else to do it but they will have trouble reaching the higher sections of the roof, unless the loft is boarded out and they can get a step into the loft - the spray will reach so far, but not all the way to the ridge. 

MeandO

Thank you all, I really appreciate your help and advice.
I have a roofer going to look at it soon to give me a price for adding extra ventilation and to double check the timbers aren't wet through or rotten so I will ask him if he could spray the mould for me whilst he's there. He is going to double check that the 'felt' is breathable too.