query: window condenstation

L

looper

Registered User
Messages
61
Hi all,

I am having issues with condenstation on the inside of my windows, which has resulted in mildew on window boards etc
does anybody know who I could get to review this issue as i need to remedy this problem once and for all.
I installed new windows 3 months ago but the issue is still occuring. There are no vents in the house so im thinking that this is the issue from reading other forums.
But before i start knocking holes in the walls i would like to get a professional opinion. Any suggestions are welcome.
 
Hi looper,

Appoint an Architect or competent Building Surveyor who understands building physics to inspect and issue a report.
He will do a study of the house first and it will usually rest with the following issues.

- Heating
- Insulation
- Orientation
- Ventilation
- Thermal bridging
- Vapour-Checking

The building should be visually inspected and considered first to establish likely causes.
Contrary to what you may have heard about visual inspection not being effective, it is the tool of choice of competent person.
This may lead to a certain amount of limited opening up works to determine what specific measures may be built in to the fabric of the building.
The will not randomly knock holes in the building - these would change the very conditions they are trying to trace, assess and quantify - a pointless exercise.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.
 
your installers while probably not legally obliged too, Should have advised you to put in window vents. In the mean time while you are waiting for wall vents, leave the windows open a little.

onq left out one important possible factor (ventilation being no.1) for your condensation and that is: your new windows! do you know what the installed window U-value is?
if the window surface temperature is lower than several degrees of the room temperature, a certain amount of moisture is always likely to condense on them (the PassivHaus suggest 3degs [broken link removed], I've read and heard others say circa 7degs). bog standard crap still being pushed on to the Irish consumer, that causes situations much worse than the 7degs.
 
Last edited:
"Thermal bridging" refers to the entire envelope windows as well as walls.

Window vents can lead to other issues, including reduced air changes if they are obscured by heavy drape curtains.
Ventilation was included but its the heat within the building that allows the air to absorb the moisture in the first place.

The hotter the air, the more moisture it can absorb, which has a counter-intuitive consequence when addressing condensation.
Heating the air further - while not insulating the envelope nor upgrading the windows not installing vents - can make things worse.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.
 
Thanks all for your inputs.
A quick history to this issue -
Before i decided on changing the windows i changed the glass in the worst bedroom (north facing) and installed a vent built into the glazing which could be opened and closed.
Condensatation was reduced even with the vent open or closed. A new issue arose - NOISE!! The noise levels in the room were a problem if the vent was open at night with passing traffic on a busy road.

installed new windows doubled glazed (glass has a U value of .95 & overall the window is 1.35). (No vents)

when the temp drops to 6deg or less this seems to cause greater condensation on the inside of the panes.
I did leave the windows open upstairs one night to try and remedy the issue and it did help but it was a wee bit nippy in the morning.
the house is a timber frame with blockwork to the external leaf.
The other evening on the north facing elevation of the house i noticed at least 70% of it was dripping wet. Is this a usual occurance - the house sweating !!
Is the house losing a lot of heat for this to occur resulting in condensation?
 
Just to be clear looper - "elevation" usually refers to the outside "face" of the building.

Was the condensation on the exterior of the house?


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.
 
do you have adequate wall vents/ ventilation in all rooms? the fact you say that where you installed a window vent, condensation was reduced, seems to point to a lack of ventilation. consider some short of demand controlled (hooked up to a RH sensor) mechanical ventilation system that could be fed (intake and extract) from the side of the house not facing the road.

also reduce the condensation in the house:

  1. make sure fan is on always when cooking
  2. " showering
  3. don't dry clothes and ensure the dryer extract is working properly
  4. open window during the day, just for a while, to freshen the air
  5. check any gas appliance's are extracting correctly, note that a gas fire gives off quiet a lot of moisture
  6. oh and don't breathe so much
 
Thanks for that,

ONQ- it was the outside elevation that had water on the surface whether it was condensation i cant be sure.
The house is a 2 storey house so if i was to install a mechanical ventilation system could it be installed in attic space and a grill in each bedroom as the condensation problem is very much an issue upstairs and then maybe 2no on the landing?
Am planning to get a building surveyor out to investigate before i spend money on another option.
 
I can't advise on the installation of mechanical ventilation systems on AAM - you could ask your surveyor to comment when you've appointed him.

Consider measures to prevent for fire-spread, sound transmission and bacterial infection - legionella etc.

As for the condensation, if it happened on the external surface of an outside wall the house its possibly pointing the way to that wall being cold because its so well insulated.

Water precipitates as condensate on any cold surface once the dewpoint is reached.
I've seen a steady stream of drips apparently 'from nowhere' on a steel fire escape stairs on a damp cold day.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.
 
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