Had all new vinyl windows installed in my house. All the windows are fine except the window in my spare bedroom where a tenant rents the room. He keeps the door closed to the bedroom 24/7 and never opens the window. After only a week and a half, the vinyl window has black spots ALL over the window. It's also the only window with condensation. I checked the humidity levels and the room is about 62% humidity. I opened the bedroom door and am running a dehumidifier in there for now.. Anyone know exactly what the black stuff is? Is it mold? Some kind of fungus? It's truly amazing that it grew in under 2 weeks. :eek:

Hi all, I live in London, England and I'm planning on extending my house, into the back garden. The House is 5.5m wide, and I'm planning a fullwidth, extension, going out 3 meters. The extension will be divided into 2 separate rooms down the middle, so I'm seeking 2 sets of 3-payne sliding doors, so each room can open out onto the garden, independently. The opening onto the garden will be around 2.6m in each room, and I'd like 2 moving and one feed payne. Can anyone give me any advice on this? Aluminium doors appears to be better, but would it make much difference (in terms of expansion from heat, or other factors) if I chose uPVC? I'll be renovating the rest of the house at the same time (it's been decades since it was last done) so trades people will already be in situ, so I'd hope to be able to save some costs on the build/installation that way, but any further advice would be greatly appreciated. Thanks, Rakesh.