You are planning a renovation. You have a vision for your Aussie home. You chose the builder. You picked the tiles. You budgeted for the new kitchen. But you have missed something vital. Air. Fresh air moving in. Stale, damp, and polluted air is moving out.
⚠️ This is not an optional extra
A $100,000 renovation fails if the house feels stuffy. It fails if it smells of damp. It fails if black mould grows on your new walls. You must plan for ventilation during renovation, not after. This is about protecting your health and your investment.
Why is Ventilation Critical During Home Renovation?
Your renovation is a process. This process creates pollutants. It happens in two phases. First, the demolition and construction. Second, the finishing and "off-gassing." Both are dangerous to your air quality.
Construction Phase
When your home gets old, there may be various safety hazards as well as aesthetic challenges to address. A home renovation is done to fix minor issues by repainting walls, replacing furniture and replastering, to major changes like introducing proper ventilation systems, remodelling entire rooms, and changing plumbing systems.
Finishing Phase
When you reach the end of your renovation process, your new carpets, cabinets, and vinyl plank floors will look great. However, they are also "off-gassing" materials. This means they release chemicals into your air.
The VOC Problem
These chemicals are called Volatile Organic Compounds, or VOCs. The smell of new paint? That is VOCs. The smell of new carpet? Also VOCs.
Paint, primers, sealants, and glues all release fumes. Engineered wood, like MDF in your cabinets, uses formaldehyde-based resins. Without ventilation, these chemicals build up inside your home. You and your family breathe them in.
Health Impacts:
- Headaches and dizziness
- Nausea and respiratory issues
- "Sick building syndrome"
- Long-term health risks
The Airtightness Trap
Modern renovations focus on energy efficiency. This is a good goal. You add high-R-value insulation. You install double-glazed windows with perfect rubber seals. You use vapour barriers. You seal every gap to stop draughts.
Great for Bills, Disaster for Air Quality
This is great for your heating and cooling bills. It is a disaster for your air quality. Your house can no longer "breathe." Old, draughty homes had accidental ventilation. Air leaked in around windows and under doors. Your new, energy-efficient home is a sealed box. It acts like a plastic bag. It traps everything inside. Every pollutant, every smell, and every drop of moisture.
Where Does Moisture Come From?
You are a source of moisture. A sealed home creates a cascade of problems. The biggest enemy is moisture. You create this moisture every single day.
Family of Four
Breathes out 6 to 8 litres of water vapour daily
Hot Shower
15-minute shower releases over a litre of water as steam
Indoor Laundry
Drying one load adds 4 to 5 litres of moisture
The Condensation Problem
This warm, moist air moves through your home. It eventually finds a cold surface. When it hits that surface, the air cools. It can no longer hold the moisture. The moisture condenses back into liquid water. This is the "dew point."
You see this clearly on windows in winter. But it also happens in places you cannot see. It happens on the cold "thermal bridge" in room corners. It happens on the wall behind your new wardrobe. It happens inside the wall cavity itself.
The Mould Threat
This condensation is a problem. It is water. And water feeds mould. Mould is a fungus. Its spores are everywhere, waiting. All they need to grow is moisture and a food source. Your new home provides both.
How Mould Grows
Mould feeds on the paper lining of your plasterboard. It feeds on the cellulose in your timber studs. It feeds on the dust in your carpet. It loves the silicone in your new bathroom. That small spot of condensation becomes a patch of mould.
Common Moulds
Aspergillus and Penicillium trigger allergies and respiratory issues
Toxic Black Mould
Stachybotrys releases mycotoxins that can cause severe health problems
The Impact on Your Renovation Investment
Structural Damage
Rots timber structures inside walls and causes floors to warp
Aesthetic Damage
Ruins paint jobs, causes bubbling and peeling
Health Hazard
Creates musty smells and an unhealthy living environment
A high-quality home reno exhaust fan is the only solution to prevent this damage.
How to Ventilate Specific Areas in Your Renovation
You cannot solve this with one fan. Ventilation is a system. It has two parts: Exhaust (removing stale air) and Supply (bringing in fresh air). The most effective strategy is "point-source ventilation" - targeting problems where they start.
🚿 Bathrooms and Laundries
This is non-negotiable. Your new bathroom will create more steam than any other room. A powerful, ducted exhaust fan is critical.
Key Requirements:
- Capacity: Fan should replace all the air 10-15 times per hour
- Ducting: Never vent into the roof space - must terminate outside
- Timer: Run the fan for 10-15 minutes after each shower
- Duct Type: Use rigid or semi-rigid ducting
👨🍳 Kitchens
Cooking releases steam, grease, smoke, and odours. A quality rangehood is your kitchen's dedicated exhaust fan.
Critical Points:
- Ducted Only: Recirculating range hoods do not provide proper ventilation
- Planning: Plan duct run before cabinet installation
- Protection: Prevents grease buildup and moisture damage
🏠 Sub-Floor (The Aussie Problem)
This is the area most renovators forget. Many Australian homes, especially older ones, have a sub-floor space that gets damp.
Solution:
- Active System: Traditional passive vents are often insufficient
- Fan-Powered: Powerful fans create a cross-flow of dry air
- Protection: Prevents rising damp and protects new floors
🏠 Roof Space
Heat builds up in your roof cavity, reaching 60-70°C on hot summer days. This acts like a giant radiator pushing heat down through your ceiling.
Ventilation Options:
- Passive: Whirlybirds (wind-powered turbines)
- Active: Powered roof fans (solar or electric)
- Benefit: Reduces AC costs and prevents winter condensation
🛋️ Living Areas
You cannot just pull air out. If you make your home airtight and install powerful exhaust fans, you create negative pressure.
Balanced Solutions:
- Simple: Dedicated "trickle" vents
- Advanced: Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV)
- Gold Standard: Transfers heat while exchanging air
Why Plan Ventilation Early in Your Renovation?
You must include ventilation in the design phase. Do not leave it as an afterthought. Ventilation during renovation is simple. Retrofitting is hard.
Cost-Effective
Easy to run ducting when walls and ceilings are open. Retrofitting costs much more and damages finished surfaces.
Aesthetically Clean
Good planning makes the system invisible. No ugly bulkheads or visible ductwork in your finished renovation.
Comprehensive Protection
Early planning ensures all areas are covered - bathrooms, kitchen, sub-floor, and living spaces.
Questions to Ask Your Builder and Architect
- Where will the bathroom fans go, and how will they be ducted outside?
- What is the planned route for the kitchen rangehood duct?
- Do I need sub-floor ventilation for my property?
- Is the roof space properly vented for Australian conditions?
- Is my home sealed so tight that I need a balanced HRV system?
A quiet, efficient ventilation system is the cheapest insurance you can buy. It protects your renovation investment, your home's structure, and your family's health.
Frequently Asked Questions
They solve different problems. If you have a damp, musty smell or are getting new timber floors, solve the sub-floor first. If your home gets extremely hot in summer, start with the roof. A healthy home often needs both.
You can buy DIY kits. If you are handy, you might install the fan unit. However, a licensed electrician must do all the wiring. Proper ducting is also tricky. A poor install (like a kinked duct) will kill the fan's performance.
No. Old fans were loud because of poor motors and bad mounting. Quality new fans are designed to be quiet. Look for a low "Sone" or "dB(A)" rating. An "in-line" fan, which hides the motor in the roof space, is almost silent.
Calculate your room's volume (Length x Width x Height). For example, a 3m x 2m bathroom with a 2.4m ceiling has a volume of 14.4 m³. To get 15 air changes per hour, you need a fan rated for at least 216 m³/h (14.4 x 15). Go higher if you have a large shower or long duct run.
Costs vary. A single, good quality bathroom exhaust fan (supply and install) might cost a few hundred dollars. A full sub-floor or roof ventilation system is a larger investment, often costing a few thousand dollars.
