black mould on windows

[seanoge]

I live on the west coast of Ireland, have just had a 30q. extension built. Black mould is starting to appear in corners and on the inside of the double glazed windows. How is this possible? The room is heated and vented regularly.
Thanks
Sean.

 

[xerxes]

What is the room used for?

Do you dry washing in it, or is it used for cooking or washing?

What form of ventilation do you have?

 

[seanoge]

It's a small hostel. This room has 4 beds not always occupied. The windows have trickle vents and the room is heated and well ventilated after use. It puzzles me that I have mould on the INSIDE of the glass.
Thanks
Sean.

 

[JohnD]

a newly built extension? could it have a roof or plumbing leak causing it to be damp? Or is it so new that the concrete and plaster are still drying out (this can take a year, and if it was built during wet weather, will be very damp)

//www.diynot.com/wiki/building:condensation_in_houses

 

[^woody^]

Mould is common on the silicone seal around new frame installations if this is not sanitary grade, and on the epdm glazing seals if even a small amount of condensation has formed at the [cold] perimeter of the glass.

This will be the case even if the room is otherwise adequately heated, ventilated and insulated.

 

[seanoge]

You may be onto something. The extension is an awkward shape and no builders were interested(Celtic Tiger) so I had to get one man to build and labour alone in his weekends off. Naturally it took months to build and we had a very wet summer so this may be why the building is not completely dried out even after 1 year. We have had a very wet year this year as well, so I suppose that doesn't help either.
But the mould on the inside of the glass of the windows I cannot understand.
Thanks everyone, I'll give it another summer and see how things go.
Sean.