On Sunday, 12 May 2019 11:52:42 UTC+1, Mathew Newton wrote:

I've just been up into our loft and was horrified to find what appears to be black mould on the underside of the roof felt:

https://thumbsnap.com/Ijt6WPKP
https://thumbsnap.com/w3zVIJbI

(Note: The white 'strips' are where the felt is overlapped)

I haven't been up there since last summer and I am certain it wasn't like that then (or at any time previously).

The house was built in 2007 and the felt appears to be of the breathable variety (it looks like a teabag when viewed close-up) however I am assuming that even a breathable felt can't work miracles if there's excessive moisture being generated in the house, particularly given how dirty the felt appears to be on the tile side? There appears to be no eaves ventilation (hard to tell as it's a 2.5 storey house so the top bedroom has hipped ceilings which mean the eaves aren't visible from the loft space).

We have a nearly-2yr old toddler and have also been undertaking a fair bit of building work over the last six months and so I think a combination of more vegetable steaming than we used to, extra loads of washing, great house occupation, reduced ventilation to 'keep the baby warm' etc have all contributed to an excess of moisture and it has condensed on the cold surface in the loft over the winter months.

If the above is true then I am sure we can remove the cause through lifestyle adjustment, however I am still concerned about the mould that is already present. Should I try and clean/remove it? If so, how and what with? It looks like most of the black mould spray cleaners contain bleach (to kill the mould and remove the staining?) and so wondered if this might damage the felt? Perhaps something without bleach more geared towards mould removal off fabric/furniture? If I just left it (and cured the cause) might some of it disappear anyway?

Bleach is the stuff to use on mould. When that's not usable I've used copper sulphate.
Is it mould though?


NT