If you're wiping water off your windows every winter morning, you're not alone. Condensation is one of the most common problems in New Zealand homes, and left alone it leads to black mould, musty smells, peeling paint and a house that feels cold no matter how much you heat it.
The short answer: make less moisture, get it out with good ventilation, and keep the house evenly warm.
What Causes Condensation?
When warm, damp air hits a cold surface like a window, wall or ceiling, it cools and turns back into water. Showers, cooking, drying clothes inside, unflued gas heaters and even breathing all add moisture. In a closed-up winter house, it ends up on your windows.
Free fixes to try first
Start here. These won't solve every case, but they'll noticeably cut condensation in most homes.
Dry clothes outside or in a vented dryer
Run the bathroom fan during showers and for 15 minutes after, and use the rangehood when cooking
Open windows for 10 minutes each morning, even in winter
Wipe windows each morning so water doesn't soak into the frames
Swap unflued gas heaters for a heat pump or electric heater
Keep rooms evenly heated. Cold bedrooms get it worst overnight
Use a dehumidifier in problem rooms as a stopgap
Still getting wet windows? It's probably ventilation
If you've done the basics and still have wet windows most mornings, your home probably just can't get rid of moisture fast enough. Modern and renovated homes are built quite airtight, which is great for warmth but means damp air gets trapped. Older homes often have the opposite issue: cold, draughty and damp.
Ventilation Systems for Hamilton Homes
At Alectrics, we install ventilation systems designed specifically for New Zealand homes.
Bathroom extractor fans and rangehoods
These remove moisture right where it's made. Every home should have a bathroom fan and a rangehood that are ducted outside, not into the ceiling. It's often the cheapest single upgrade that makes a real difference.
Positive pressure (e.g. SmartVent)
A cost-effective option for older homes experiencing condensation and dampness.
Heat recovery (e.g. Lossnay)
Swaps stale indoor air for fresh outdoor air, keeping the heat. Best for newer, well-insulated homes.
Ducted Heat Pump + Ventilation
For homeowners wanting the best long-term comfort solution, combining a ducted heat pump system with Lossnay ventilation can completely transform how a home feels. Ideal for new builds and big renovations.
Can Ventilation Help with Mould?
Yes.
Reducing excess moisture is one of the most important steps in controlling mould growth.
While ventilation won’t fix structural leaks or water ingress, it can dramatically improve everyday moisture build-up caused by normal living.
Do Heat Pumps Stop Condensation?
Not completely.
Heat pumps help warm your home, which can reduce moisture settling on surfaces — but they don’t remove stale, humid air from the home.
Ventilation systems solve a different problem:
airflow
moisture control
fresh air circulation
The best results often come from combining both.
How Much Does It Cost to Fix Condensation?
It depends on what's causing it:
Free to under $100: changing habits, a squeegee, better curtains
Replacing or ducting an extractor fan: From $450
Positive pressure system: From $3,000
Heat recovery system: From $3,800
Ducted heating plus ventilation: From $15,000
Please note these are rough ballpark figures, for an accurate quote, get in touch.
We can come out, find where the moisture is coming from and tell you the simplest fix. Sometimes that's just a better fan.
SmartVent Results for a Hamilton client
"The difference the system has made, we're stoked, thanks"
Frequently asked questions
How do I stop condensation on my windows overnight?
Cut the moisture going into the air (dry clothes outside, use your extractor fans, no unflued gas heaters), keep bedrooms gently heated, and leave a door or window slightly open. If windows are still wet every morning, your home likely needs better ventilation.
What's the fastest way to get rid of condensation?
Wipe the windows, open them for 10 minutes and run a dehumidifier. That clears it for the day. To stop it coming back, you need to deal with where the moisture is coming from and how it gets out.
Does opening windows stop condensation?
A short airing each morning helps a lot. But in a New Zealand winter, most people won't keep windows open long enough to fix the problem, which is why mechanical ventilation is the long-term answer for many homes.
Does a dehumidifier stop condensation?
It reduces it in the room it's in, and it's a good short-term fix. It doesn't fix the cause, it costs power to run and it needs emptying. Ventilation deals with the whole house.
How do I stop condensation and mould?
Clean existing mould with white vinegar, then stop the moisture that feeds it: better extractor fans, even heating and a ventilation system if needed. Mould keeps coming back until the damp is sorted.
Why is my house so damp even with the heater on?
Common causes are damp ground under the house, unflued gas heaters, poor ventilation or missing insulation. If your house has an enclosed subfloor, a ground moisture barrier (polythene sheeting laid on the ground underneath) can make a big difference. It's also a Healthy Homes requirement for rentals.
What is a SmartVent and how does it work?
SmartVent is a brand of positive pressure ventilation. It draws air from the roof space, filters it and gently pushes it into the house, which forces damp, stale air out. More on SmartVent systems.
Do I need an electrician to install an extractor fan or ventilation system?
Yes. Any fan or system that's hardwired needs to be installed by a licensed electrician in New Zealand. Plug-in dehumidifiers are fine to use yourself.
Do rentals have to have extractor fans?
Yes. Under the Healthy Homes Standards, rental kitchens and bathrooms need extractor fans vented outside, along with openable windows in living areas and bedrooms. See our Healthy Homes page.
Not sure what's causing your condensation?
Every home is different.
At Alectrics, we don’t push one system, we help you find the right solution for your home, lifestyle, and budget.
👉 Book a consultation today and start creating a healthier, drier home.
