Another attic condensation post

dr_bogenbroom

I upgraded our insulation in our roof from 100mm to about 400mm - I have these plastic things at the eaves that I assumed were to allow airflow and put the insulation up to these.

After the first cold spell I noticed it was soaking up there - condensation everywhere so I pulled back the insulation from the eaves, left the loft hatch and the bedroom window open for a few days, and wiped down/vacuumed as much moisture as possible until it was clear.

Checked again today and even though it’s pretty much the outside temperature up there it’s coming back. I wondered if the heat from the hot water tank below was maybe causing it but that’s also got about 400mm of insulation above it.

I then thought it could be that I’ve put too much insulation up there and that I’ll have to remove some. 

And then I could add vents to the top of the roof. 

Any ideas?

ThisIsWeird

On a windy day, does it feel draughty up there?

Provided you haven't covered the eaves ventilation - and it sounds as tho' you have taken good steps to avoid this - then don't worry too much at the mo' - just monitor it.

But, close the hatch! That's letting warm, moist air up from the house - a waste of heat, but also a cause of condensation

Does the hatch seal quite nicely when shut?

It isn't unusual to get some condensation up there at times, usually when there's a cold spell coupled with light (ventilating) winds. If you are happy that there's decent cross-ventilation up there, then simply monitor the situation for a few weeks, and see if it dries away by itself. If it does - and chances are it will - you shouldn't have anything to worry about.

But keep the hatch closed!

And, you cannot have too much insulation, provided it doesn't block the vent flow.

dr_bogenbroom

ThisIsWeird said:

On a windy day, does it feel draughty up there?

Provided you haven't covered the eaves ventilation - and it sounds as tho' you have taken good steps to avoid this - then don't worry too much at the mo' - just monitor it.

But, close the hatch! That's letting warm, moist air up from the house - a waste of heat, but also a cause of condensation

Does the hatch seal quite nicely when shut?

It isn't unusual to get some condensation up there at times, usually when there's a cold spell coupled with light (ventilating) winds. If you are happy that there's decent cross-ventilation up there, then simply monitor the situation for a few weeks, and see if it dries away by itself. If it does - and chances are it will - you shouldn't have anything to worry about.

But keep the hatch closed!

And, you cannot have too much insulation, provided it doesn't block the vent flow.

Thanks - I’ll not panic as much then. Not sure how much wind gets in there but I’ll check at some point. It has been really cold here but with no wind so that could explain it

stuart45

It's quite common in older houses to get condensation in the roof space when you add extra insulation without increasing the ventilation.

dr_bogenbroom

stuart45 said:

It's quite common in older houses to get condensation in the roof space when you add extra insulation without increasing the ventilation.

Yes - I need some roof repairs done so I’m going to get them to add some tile vents to help air flow better