Attic condensation

Ola,

I have searched for this topic, and it has come up many times in the past. I have a question about my specific situation.

In the attic of this 10 year old house, semi-detached, there is condensation on the black roof fabric. This is forming into drops, and there are drops of water on the attic insulation fiberglass. I wanted to add more insulation, but I'm thinking the condensation should be fixed first.

Venting is the solution, right? There are several horizontal vents at the eaves. They seem quite narrow (5cm?) and long (20cm?). On the front of the house, I can only see daylight peeking in in one place. Perhaps there are others that are covered by insulation. On the side of the house, there is one vent. On the back of the house I can see three vents.

A fan in an upstairs ensuite leads through a pipe that runs out through the attic. I can only presume this piping is sealed.

What would you suggest to be the starting point of addressing the condensation? Do more vents need to go in place? The insulation is 4inches thick, not the best, so perhaps it's just heat escaping from the house upwards...?

Eoin

eoinoc333 said:

Perhaps there are others that are covered by insulation.

Click to expand...

This sounds like your main problem. It would also be very important to double check the extraction from the ensuite.

Thanks.

I'm a wuss I'll try to get that far under the slanted roof to check it.

You've got to stop the moistured air getting through to the felt. The usual way for avoiding this is to staple a layer of 1000 guage polythene between the fibreglass and the plasterboard.

The surface under the fiberglass between the joists is reflexive, like foil.