I recently went up into my attic and noticed that the felt/membrane underneath the roof tiles, which I remember being a light grey/white colour, now appears to have turned quite dark, almost black, across much of the attic.
One thing I'm wondering about is the large black cold-water storage tank up there. I'm in Ireland, and this tank supplies water to the bathroom taps and toilets. I've noticed that the tank is completely open at the top, with no lid or covering whatsoever.
Could moisture evaporating from this tank be contributing to condensation in the attic and potentially causing mould to develop on the roof felt?
A few questions for anyone who might know:
- Is roof felt turning black generally a sign of mould, or can this happen naturally as it ages?
- Could an uncovered water storage tank contribute enough moisture to cause this?
- Should I be concerned about the attic ventilation?
- What's the best way to establish what's actually happening before it becomes a bigger problem?
I'll be getting a proper lid for the tank regardless, as I suspect it shouldn't have been left uncovered in the first place!
Any advice or similar experiences would be greatly appreciated. I'm not particularly knowledgeable about roofing, so apologies if this is a silly question.
Thanks in advance!