How to Stop & Eliminate Condensation on Windows

How to eliminate condensation on windows

This is one of the most common questions we get asked… and the answer is actually straight forward. Click Here to see how you can do it within minutes!

Let me start by saying that I’m in NZ houses almost every day of the week testing for moisture, or inspecting houses for ‘leaks’ under windows. Well, in many cases they are not actually leaks coming in from the outside (i.e. Weather tightness issues), it’s condensation pouring down the windows and straight into the walls! This is especially the case for windows with no condensation channels, or situations where the miter joints have failed. Even some homes with double glazed windows still get moisture beading on the aluminum frame due to a high moisture content in the air.

“How do you stop condensation?”

Click Here to see how you reduce condensation within minutes!

If you have single glazed windows, then you’re in for an uphill battle right from the get go. Homes with single glazing will always be susceptible to moisture and damp issues if there is no air circulation. A classic example of ‘lack of air circulation’ is when a home owner calls telling us their basement is damp. If you smell damp in the basement of your house, simply ‘test’ putting a dehumidifier in the room. If the smell fades away after a few days, then you know it’s simply moist air. If the smell remains (providing it’s not a permanent smell in carpet), then you could have other moisture/drainage related problems, especially if the external walls are built into the side of a hill.

Back to stopping window condensation…

If you and/or your children are sleeping in a room with condensation on the windows, you should put a stop to this asap, purely for health purposes if anything. If you or someone in your home gets asthma, or generally gets sick over winter, then you need to do your best to begin a logical ‘process of elimination’ of what could be causing the problem. Here’s a few options to test…

  • Put a dehumidifier in the room… if it fills with water in 24hrs or less, you know the air is very moist! Consider getting some kind of system installed that works 24/7 to keep your home dry and healthy (HRV, DVS, Moisture Master etc).
  • If the dehumidifier doesn’t work, go for a holiday somewhere and sleep in a different environment for 5 days or so. Has the health condition of the person changed in a positive way? You might find it will, therefore your house is the problem.
  • Are the bedroom curtains moist? They most likely will be if you have condensation. Curtains in moist rooms act like a big sponge… further introducing ‘sustainable’ damp in the room. Not good.
    As a result of moisture on the back curtains (transferred from the wet windows), mould will start growing on the curtain, potentially causing further health issues! Try using this mould cleaning product on curtains…
  • Here is your best option… Click Here to see how you can manage and control condesation on windows within minutes!

Double glazed windows will certainly help reduce condensation, and also help to retain any heat that is introduced into the room. If you live in a damp area of NZ and are constantly getting sick, then you may have no choice but to sell up and leave! That is the extreme case I know, but many people take this option to resolve moisture related health problems almost right away. Why would you compromise your lifestyle and health, when you could be living somewhere warmer, healthier and generally a dryer environment!

In summary, NZ has moist climatic conditions over winter and there is nothing that you or I can do about part of it… but there are always ways around it, generally at a cost. Before you hit the panic button, the best low-cost place to start is with moisture testing the home to make sure the problem isn’t originating from behind the wall, which is often the case… and usually doesn’t cost much to fix providing it’s not a widespread moisture ingress isssue.

Condensation Moisture – Ants crawling out corner of window sill?

Have you noticed signs of timber rot in the corners of your window sills?

One on the ‘red flags’ that will normally catch my eye when doing a thermal home moisture inspection, is when the window sill has a soft spot up against the window joinery OR if ants are crawling out of the sill in the area.

Recently during a moisture inspection, my equipment detected signs of moisture behind the wall under a window. There was a builder with me at the time of inspection, and without hesitating, he pulled off the gib board on the spot.

Here’s what the thermal camera detected (Dark area in bottom right corner indicates a potential issue)


What did we find behind this area?

Ant nests, black mould, rotted timber and all the things you don’t want to see if you own the home. Who else was there? The tenant. The tenant had 3 kids and went into a panic due to the unhealthy aspect of the home… like black mould spores floating into the air etc.

Typical: The home owner didn’t even know the window sills were rotting, because the tenants didn’t say a word about these issues when they first appeared, and now the vendor has some serious remedial work to undertake. (The cladding was plaster with no cavity). On top of that, the tenant is now taking this to the rental tribunal to get out of the lease on the grounds of an unhealthy home.

The message here is that if you own a home that is rented out, and it’s built between 1992-2004, then you should consider a thermal moisture ‘check up’ to detect potential problems caused by joinery leaks and window condensation… before the whole wall rots due to gradual leak damage!

Should you bother getting an infrared moisture scan? Take a look around this website to see what other types of leaks our thermal camera has found behind walls…

Window Condensation Channel Leak – Mitre Joint Failure

Home buyers beware…

Window condensation channel failure causes leak issues.

Have you ever noticed how leaks seem to appear under the corners of windows more often then any other place in the home? They appear all the time, and usually you can’t see 70% of them with the naked eye! Not only that, most of the time the window looks really well sealed where the aluminium window frame meets the cladding.

As you can see in the infrared thermal imaging photo below, there is a dark spot in the corner of the window. That dark spot is hidden moisture the home owner knew nothing about…

Leak Caused by Mitre Joint Failure
Leak Caused by Mitre Joint Failure

The mitre joints in most windows are vulnerable to losing their seal, and the slightest movement in the house can cause this. It’s rare to physically see the seal has failed because water only needs the slightest of gaps to escape… and it likes to escape right onto your timber frame behind your walls!

An infrared imaging camera in conjunction with quality moisture testing equipment on your home will detect these types of issues…  and to be fair, we would have missed 90% of the hidden leaks we’ve found in NZ houses without the support of the instruments we use.

If there are windows in the house, then there is potential for leaks… which could result in gradual leak damage and/or timber rot. Don’t risk buying a home without this type of testing… otherwise it could get very costly, especially if  the joinery throughout the house is low quality (plenty of that around NZ).