Lady in Cashmere called us about her bathroom. Every time someone had a shower the ceiling would drip for hours after. Paint was peeling, black mould growing in corners, whole bathroom smelled damp. She had an extractor fan but it wasnt doing anything. Turned out the previous owner had installed the fan but never ducted it to outside - it was just blowing moist air into the ceiling cavity. All that moisture had nowhere to go so it condensed on the cold ceiling and dripped back down. We installed proper ducting to vent outside, sealed it all up properly. Month later she said the bathroom stays dry now, moulds gone, paint stopped peeling. Simple fix but makes huge difference when done right.
Thats pretty typical. People install fans thinking theyll solve moisture problems but if the fans not vented properly it does nothing or makes things worse.
Why You Need Extractor Fans
Extractor fans remove moisture and smells from bathrooms, kitchens, laundries. Christchurch has damp weather so moisture control is important.
Bathrooms generate heaps of moisture. Hot shower in winter creates steam that condenses on cold surfaces. Without ventilation that moisture stays in the bathroom causing mould, mildew, peeling paint, rotting timber.
Kitchens produce moisture from cooking plus grease and food smells. Rangehoods remove cooking fumes before they spread through your house and leave everything greasy.
Laundries get moisture from washing machines and dryers. Even condensing dryers produce some moisture. Extractor fans help keep laundries dry.
Toilets need ventilation to remove odors. Building code requires mechanical ventilation if theres no openable window.
Moisture causes serious problems. Mould grows which is bad for health specially kids and people with asthma. Timber rots. Paint peels. Walls get damaged. Prevention is way cheaper than fixing the damage later.
Did a house in New Brighton where bathroom had no fan for years. When we opened up the ceiling to install one the roof framing was rotting from all the moisture. Cost thousands to repair the timber before we could even install the fan. If theyd put a fan in years ago wouldve saved all that hassle.
Types of Extractor Fans
Different types of fans for different jobs.
Ceiling mounted fans sit in the ceiling and duct to outside. Most common type for bathrooms. Quiet, out of the way, move good amounts of air.
Wall mounted fans install in external walls. Duct straight through wall to outside. Good when you cant run ducting through ceiling or roof.
Inline fans sit in the ducting between ceiling and outside. Fan is in roof space or attic, connected to duct. Very quiet cause the fans not in the room. Good for bathrooms where you want minimal noise.
Rangehoods for kitchens. Either ducted to outside or recirculating with filters. Ducted ones are way better cause they actually remove the air instead of just filtering it.
Window fans mount in windows. Cheap option but not as effective as ceiling fans and dont look as good.
We usually recommend ceiling mounted for bathrooms, inline if noise is a concern, ducted rangehoods for kitchens.
How Extractor Fans Work
Extractor fans pull air out of the room and vent it outside.
Fan motor spins blades that pull air through the fan. Air gets sucked up from room, pushed through ducting, vented outside.
Ducting is the path air takes from fan to outside. Usually flexible or rigid duct pipe through ceiling, sometimes through walls. Has to terminate outside not just in ceiling space.
External vent caps on the outside keep rain and bugs out while letting air escape. Different designs for walls vs roofs.
Backdraft dampers in the ducting close when fan is off so cold air doesnt come back in. Opens when fan runs.
Fan capacity is measured in litres per second or cubic metres per hour. Bigger bathrooms need more powerful fans. Building code specifies minimum ventilation rates.
Installing Bathroom Extractor Fans
Bathroom fan installation involves electrical, ducting, and sometimes building work.
We start by figuring out where the fan should go. Usually center of ceiling or above shower where most moisture is. Check ceiling space access and where ducting will run.
Cut hole in ceiling for the fan. Size depends on fan model. Install the fan housing in the ceiling, secure it to framing.
Run electrical cable from nearest power source to the fan. Usually connects to lighting circuit so fan comes on with light switch. Sometimes separate switch or timer.
Install ducting from fan to outside. Shortest run possible with minimum bends cause bends reduce airflow. Use proper duct clamps and seal joints.
Make hole through wall or roof for external vent. Install vent cap, weatherproof it properly so no leaks.
Wire up the fan, test it works, install the cover grille.
Whole job usually takes 2-3 hours for straightforward bathroom installation. Can take longer if roof access is difficult or long duct runs needed.
Building consent might be required depending on scope of work. We handle that if needed.
Fan Switches and Controls
Different ways to control when fans run.
Light switch control is simplest. Fan comes on when you turn bathroom light on, goes off when light goes off. Problem is people turn light off before fan has cleared the moisture.
Separate switch gives you control over fan independent of lights. Can leave fan running after you leave bathroom. But people forget to turn it off and waste power.
Timer switches run fan for set time then turn off automatically. Turn it on, it runs for 10-20 minutes then shuts off. Good compromise - fan runs long enough to clear moisture but doesnt stay on forever.
Humidity sensors turn fan on automatically when moisture levels get high. Fan runs til humidity drops then switches off. Most automatic option - never have to think about it.
We usually recommend timer switches for bathrooms. Give you manual control plus automatic shutoff. Humidity sensors are good but cost more.
Kitchen Rangehood Installation
Rangehoods remove cooking fumes, grease, moisture, smells from your kitchen.
Ducted rangehoods vent outside like bathroom fans. Way more effective than recirculating ones. Removes everything instead of just filtering some of it.
Rangehood sits above your cooktop. Height matters - too low and you hit your head, too high and it doesnt catch the fumes. Usually 650-750mm above cooktop.
Ducting size for rangehoods is bigger than bathroom fans cause they move more air. Usually 150mm diameter. Run through ceiling, through wall, shortest route possible.
Electrical for rangehoods needs proper circuit. Larger rangehoods pull decent power. Some need dedicated circuits.
Installation process similar to bathroom fans but bigger ducting, heavier unit, more precise mounting cause its visible and has to look good.
For islands (cooktop in middle of kitchen) you can do ceiling mounted rangehood with ducting running up into ceiling. More complex installation but works well.
Did a kitchen in Merivale with big 900mm rangehood above 5 burner gas cooktop. Ducted straight through outside wall behind it. Thing moves so much air the kitchen stays clear even when theyre cooking up a storm.
Ducting Best Practices
Proper ducting is critical for fans to work well. Dodgy ducting ruins even good fans.
Use smooth rigid ducting where possible. Flexible ducting is OK for short runs but creates more resistance. Smooth is better than ribbed flexible.
Keep runs as short as possible. Every meter of ducting reduces airflow. Every bend reduces it more.
Minimize bends. Each 90 degree bend is equivalent to adding several meters of straight duct. Two 45 degree bends better than one 90.
Slope ducting slightly toward outside so condensation drains out instead of pooling.
Insulate ducting if it runs through cold spaces like unheated roofs. Prevents condensation forming inside the duct.
Seal all joints properly. Leaky ducting means moist air goes into ceiling instead of outside.
Terminate outside not in ceiling cavity or under eaves. Has to actually go outside.
Use proper vent caps that keep rain and pests out. Different types for walls vs roofs.
Seen heaps of dodgy ducting over the years. Flexible duct with 5 bends running 10 meters through roof. Fan cant push air through all that. Duct not sealed so moisture leaks into ceiling. Vent terminating under eaves so air just blows into soffit. All useless.
Fan Sizing and Capacity
Fans need enough capacity to actually move the air.
Building code specifies minimum ventilation rates. Bathrooms need 25 litres per second typically. Bigger bathrooms need more.
Kitchens need way more airflow. Rangehoods rated for their cooktop size. 900mm cooktop needs bigger rangehood than 600mm one.
Ducting length and bends affect what fan you need. Long duct runs with bends create resistance. Need more powerful fan to overcome it.
We calculate required fan capacity based on room size, duct length, bends, elevation changes. Make sure fan is powerful enough for the application.
Noise level matters too. More powerful fans are usually noisier. Sone rating tells you noise level - lower is quieter. Inline fans are quietest cause motors in ceiling not in room.
Common Extractor Fan Problems
Things that go wrong with extractor fans.
Fan not ducted outside. Just venting into ceiling cavity. Does nothing useful and causes moisture damage in roof space.
Ducting too long with too many bends. Fan cant move enough air through all that resistance. Room stays steamy.
Ducting not sealed. Leaks let moist air escape into ceiling before it gets outside.
Undersized fan for the space. Doesnt move enough air to actually clear moisture.
Backdraft damper stuck closed or missing. Cold air comes back in through duct making room cold.
Fan full of dust and grease. Reduces airflow and makes fan noisy. Need cleaning.
Vent cap blocked by birds nest or other debris. Air cant escape.
Fan motor failed. No airflow at all even though fan sounds like its running.
Timer or switch failed. Fan wont turn on.
Most of these are fixable. We diagnose the problem and sort it out.
Replacing Old or Broken Fans
Old fans eventually need replacing. Motors wear out, plastic cracks, performance drops.
Signs you need new fan: loud bearing noise, not moving much air anymore, visible damage, doesnt turn on.
Modern fans are quieter and more efficient than old ones. Upgrading makes sense even if old fans still working.
Replacement usually straightforward. Remove old fan, install new one in same hole, reuse existing ducting if its in good shape. Might need to adjust hole size if new fans different dimensions.
Good time to check ducting while replacing fan. Make sure its still sealed and terminating properly outside.
Cost to replace bathroom fan $250-400 depending on fan quality and any ducting work needed.
Had customer in St Albans with bathroom fan from the 1980s. Thing sounded like jet engine and barely moved any air. We replaced it with modern quiet fan - they couldnt believe the difference. Actually clears steam now and you can barely hear it running.
Maintenance and Cleaning
Extractor fans need maintenance to keep working well.
Clean fan grilles every few months. Dust and lint build up reducing airflow. Just vacuum them or wash with soapy water.
Rangehood filters need regular cleaning. Grease builds up and blocks airflow. Most filters are dishwasher safe.
Inside the fan housing gets dusty over time. Turn off power, remove cover, vacuum out dust. Be gentle around fan blades.
Check ducting connections occasionally. Make sure joints havent come apart and nothing is blocking duct.
External vent caps should be checked yearly. Birds sometimes nest in them. Clear any blockages.
Listen for changes in noise. If fan gets louder bearings might be wearing out. Time to replace before it fails completely.
Most people never clean their fans til they stop working. Regular maintenance keeps them running longer.
Ventilation Requirements and Building Code
Building code has requirements for ventilation in wet areas.
Bathrooms need mechanical ventilation (fan) if theres no openable window. Even with window a fans still a good idea.
Minimum ventilation rate is 25 litres per second for standard bathrooms. Bigger bathrooms need more.
Kitchens need ventilation over cooktops. Rangehoods or other exhaust systems required by code.
All ventilation has to actually vent outside. Not into ceiling cavities or under eaves.
We make sure installations meet code requirements. Get it inspected and signed off if needed.
Condensation and Moisture Problems
Proper ventilation prevents condensation damage.
Condensation happens when warm moist air hits cold surfaces. Water vapor turns to liquid. In bathrooms this means dripping ceilings, wet walls, puddles.
Without ventilation moisture accumulates. Causes mould growth, paint damage, timber rot, health problems.
Extractor fans remove moist air before it condenses. Run fan during shower and for 10-20 minutes after to clear all the moisture.
In winter condensation is worse cause bigger temperature difference between inside and outside. Fans are even more important.
Some houses have condensation problems even with fans. Might need better insulation or more powerful ventilation. We assess the situation and recommend solutions.
Quiet Fans for Bathrooms
Noise bothers some people. Want ventilation without loud fan noise.
Inline fans are quietest option. Motor sits in roof space, connected to duct. Only hear air movement not motor noise. Cost more but worth it if noise matters.
DC motor fans run quieter than old AC motor ones. More efficient too.
Quality fans are quieter than cheap ones. Better bearings, balanced blades, sound insulation. Worth paying extra for good fan.
Proper installation reduces noise. Make sure fan is secured solidly so it doesnt vibrate. Flexible ducting connections prevent vibration transmitting through duct.
Some noise is unavoidable - air movement makes some sound. But modern fans are way quieter than old ones.
Cost of Extractor Fan Installation
Installation costs depend on complexity.
Basic bathroom fan with short duct run - $400-600 installed including fan, ducting, electrical, vent cap.
Inline fan for quiet operation - $600-900 cause fans more expensive and installations more involved.
Kitchen rangehood installation - $500-1000 depending on rangehood size, ducting distance, mounting complexity.
Long difficult duct runs cost more. Running ducting 10 meters through complicated roof space takes more time and materials.
Wall venting is usually cheaper than roof venting cause less work.
Timer switches or humidity sensors add $50-150 to cost depending on type.
Building consent if required adds $500-800.
These are rough prices. We provide quotes once we see your place and know exactly whats involved.
Laundry Extractor Fans
Laundries benefit from ventilation too.
Washing machines produce moisture. Dryers produce heaps of moisture and heat even condensing dryers release some.
Without ventilation laundries get damp and musty. Extractor fan removes moisture and helps clothes dry faster if you hang them in there.
Installation same as bathroom fans. Ceiling or wall mounted, ducted outside. Can wire to come on with light or have separate switch.
If you got gas hot water cylinder in laundry ventilation is required by code for safety. Gas appliances need fresh air.
Retrofitting Fans in Existing Houses
Adding fans to older houses that dont have them.
Lots of older christchurch houses dont have extractor fans cause they werent required when built. Moisture problems develop over years.
Retrofitting is usually straightforward. Cut hole for fan, run ducting, make external vent, wire it up. Main challenge is accessing ceiling spaces specially in houses with low roofs or difficult access.
Wall mounting is option if ceiling access is impossible. Duct straight through wall to outside. Not as neat as ceiling mount but works fine.
Cost similar to new installation maybe bit more if access is difficult.
Huge improvement to houses that never had proper ventilation. Solves moisture problems that have existed for decades.
Commercial Extractor Fan Installation
Commercial properties need bigger ventilation systems.
Restaurant kitchens need commercial grade rangehoods. Way bigger than residential. Multiple fans, grease traps, fire suppression sometimes. Building consent always required.
Commercial bathrooms need more powerful fans cause higher usage. Multiple fans or big inline systems.
Industrial spaces might need specialized exhaust systems for fumes or dust. We do light industrial not heavy industrial.
Commercial work more complex than residential. More regulations, bigger systems, higher standards. But same basic principles - remove contaminated air, vent it outside properly.
When DIY Goes Wrong
People try to install fans themselves and often stuff it up.
Electrical done wrong is dangerous. Fans in bathrooms need proper IP rating and correct wiring. DIY electrical can kill you or burn your house down.
Ducting done wrong means fan doesnt work. Seen DIY installations with ducting just dumped in ceiling, terminating under eaves, full of leaks, way too many bends.
Wrong fan for the application. Buy cheap fan thats too small, doesnt move enough air.
Installation not weatherproof. External vents leak letting rain in.
Then we get called to fix it and often costs more than doing it right the first time.
Extractor fans arent that expensive to have installed properly. Save yourself the hassle and potential damage - hire licensed electricians.