Window Reeval Condensation

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Hi - we got our local builder to install a upvc window to replace an old wooden one and at the same time, we had the thick (50cm), solid stone walls dry-lined with 62mm board. At the time I mentioned to the builder that it seemed to me that the window reveals might get cold and form condensation but he reckoned we'd be OK.

So, now that we have water running down the reveals, I'm hoping to figure out an easy solution! One issue is that on one side, the window reveal is in line with an internal wall.

On another room, which I had a go at myself after this one, I did all the above but also used a very thin plasterboard/insulation laminate (about 20mm total) in the reveals and this seems to work. However, doing this on the first room will need quite major hacking of the walls and then hoping that we can get an inch of material off the wall to be able to sink the thin board enough to avoid a step at the reveal. Then plastering etc. The room has new carpets, paintwork etc...


Is there another way? Paints etc?

Thanks
 
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Insulating the windows and walls doesn't suddenly make the reveals worse. What has happened is that the humidity in the house has increased. This is partly due to VPL in the dry lining, partly because you might have forgotten to fit trickle vents and partly because you don't get condensation on the windows to dry the air by the reveals.

I think the recommendation for reveals in 'sealed houses' is 20 mm of PIR plus whatever surface finish. So you might need an R value of at least 0.8 to protect from condensation. You could look at exotics, like aerogel. http://www.buyfoam.co.uk/#/aerogel/4533238407

Another alternative is to increase the ventilation to drop the internal humidity back to what it used to be and so lower the dew point below the temperature of the reveals. Options include opening windows, fitting trickle vents and up to positive input ventilation (PIV) like Nuaire Drimaster.

Thick curtains are bad for condensation; they lower the temperature of the reveals.
 
Insulating the windows and walls doesn't suddenly make the reveals worse. What has happened is that the humidity in the house has increased. This is partly due to VPL in the dry lining, partly because you might have forgotten to fit trickle vents and partly because you don't get condensation on the windows to dry the air by the reveals.

I think the recommendation for reveals in 'sealed houses' is 20 mm of PIR plus whatever surface finish. So you might need an R value of at least 0.8 to protect from condensation. You could look at exotics, like aerogel. http://www.buyfoam.co.uk/#/aerogel/4533238407

Another alternative is to increase the ventilation to drop the internal humidity back to what it used to be and so lower the dew point below the temperature of the reveals. Options include opening windows, fitting trickle vents and up to positive input ventilation (PIV) like Nuaire Drimaster.

Thick curtains are bad for condensation; they lower the temperature of the reveals.

Wow, that is a comprehensive reply, many thanks.

I assumed that the uninsulated reveals presented a cold surface whereas the window and walls no longer do so that the moisture already present in the air would then condense there.

The windows were fitted without trickle vents so I'll find out whether/how they may be retro-fitted as it sounds like the easiest first course of action. We were advised that trickle vents were a waste of time and would just undo the good-work of the double-glazing, but it seems that this may not have been the best advice.

Thanks again, Patrick
 
:oops: I should retract my first statement. Actually, internal insulation of walls will make the masonry colder and more prone to condensation. However, ventilation is always necessary (for health as well as humidity control). Even if you insulate the reveals to tackle visible condensation, you might still have openings in your VPL that allow humid air to reach the cold masonry and condense in hidden areas.
 
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I think that the uninsulated walls won't change in temperature but will be colder than the rest of the walls and so, as you say, the double glazed windows will help keep the humidity up and so these walls will have more condensate. Will fit trickle vents, but still confused as to why they don't undo the good work of increasing the insulation. Better ventilation I do see though.

Is there any easy way to insulate the reveals without having to hack all the plaster off in order to cut back far enough for a thick insulation/plasterboard sheet to be fitted? Is there some sort of insulative paint or something that will work?
 
Will fit trickle vents, but still confused as to why they don't undo the good work of increasing the insulation. Better ventilation I do see though.
Yes, they do let some warm (humid) air escape. However, my stepson recently bought a new build semi in Leeds with modern insulation and trickle vents. Last November, they still hadn't put the heating on but it was warm enough (and I am a delicate flower). I could feel a slight draught right next to the vents, so they were definitely working. My point is, trickle vents lose some heat, but not much. You can always close them when the room is unoccupied, if you can be bothered.

I think the EU are looking to ban uncontrolled ventilation in future builds, which should be good news for Nuaire.
 

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