Most homes have small gaps that let outside air in and inside air out. You rarely notice them until a cold night or a windy afternoon. Then the heater runs longer and the room never quite feels right. Draught proofing is the simple job of finding those gaps and closing them.
It is one of the cheaper home improvements you can do. Much of it needs only a few basic tools and a weekend. Some parts are best left to a licensed tradesperson, and we cover those below. Here is where the gaps tend to hide and what to use on each one.
Why draughts matter for comfort and bills
Draughts are uncontrolled air leaks. Sustainability Victoria says up to 25 per cent of winter heat loss from existing houses comes from air leakage. It also says nine in ten Victorian homes have unwanted draughts. That is a lot of paid for warmth slipping out through cracks.
CSIRO researchers have found that Australian homes are leaky by international standards. Older buildings are generally much draughtier than new ones. CSIRO says unintentional draughts in southern Australia can add up to 20 per cent to an energy bill. Older weatherboard houses on stumps are among the leakiest, while concrete slabs leak much less.
The same gaps work against you in hot weather too. Cooled air from a split system escapes and warm outside air creeps in. If your rooms heat up fast in summer, read about how Perth heat affects your windows and energy bills. Sealing gaps and shading glass work well together.
How to find the gaps
You do not need special gear to find most draughts. Sustainability Victoria suggests looking for light showing under and around doors and windows. Listen for rattles or whistling on a windy day. Watch the curtains for movement when the windows are shut.
Your hand is a good tool as well. Feel for moving air around doors, windows, fireplaces, vents and stairways. Check floorboards, skirting boards and architraves too. Built in heaters and air conditioners are also common leak points.
Professionals can run a blower door test for a more accurate result. CSIRO explains that this test measures air changes per hour and finds where cold air gets in. Sustainability Victoria notes that trained professionals may be able to measure leakage more accurately. That may be worth it for an older or very draughty home.
Where draughts usually hide
CSIRO lists a set of common leak points in Australian homes. Some are obvious and some are easy to miss. Walk through the house with this list and note what you find.
- Edges of doors and windows
- Gaps in floorboards, mainly in raised timber homes
- Where skirting meets the wall and where bricks meet timber trim
- Old fireplaces and holes left after services were removed
- Fixed ceiling and wall vents in some older brick homes
- Old exhaust fans and evaporative cooler vents
- Gaps around pipes, built in appliances, cupboards and under the kitchen sink
Sealing doors
Doors need sealing in two places. One is the base and the other is the gap between the door and its frame. Council guidance lists several options for the base. A door snake is a fabric tube that lies along the bottom and needs no fitting.
For a more permanent fix, a bottom door seal fixes to the base of the door. It sweeps against the floor as the door closes. Where that will not work, a threshold seal fits to the base of the frame and the door closes onto it. CSIRO suggests a plastic or metal seal with wipers for external doors.
Around the frame, use weather strips made from foam, rubber or brush. Foam and rubber suit doors that close straight onto the frame. Brush seals suit sliding doors. Clean the surface first, cut the strip to length and trim it if the door will not close properly.
Sealing windows
Windows leak where the opening part meets the frame. The same weather strips used on doors work here. Brush seals suit sliding and sash windows. Cracks around the frame can be filled with caulk or sealant using a sealant gun.
Glass itself loses heat even when the frame is sealed. CSIRO says uncovered windows can account for up to 40 per cent of winter heat loss. Heavy lined curtains that fall below the window sill help. Pelmets above curtains stop warm air escaping over the top.
Longer term options include double glazing, window film and insulating window coverings. These cost more than a pack of weather strips. They are worth pricing if your windows are old or face strong sun or wind.
Floors, skirting and small cracks
Raised timber floors can let a steady stream of air up between the boards. CSIRO suggests silicone sealant for small gaps. Larger gaps can be filled with expanding spray foam. Wear gloves and a face mask when working with sealants.
Check where the skirting meets the wall and the floor. Look behind cupboards and under the sink where pipes pass through. These spots are quick to seal once you know they are there. A tidy bead of sealant is usually all it takes.
If you are replacing floors as part of a renovation, the choice of surface matters too. A sealed slab leaks much less than old boards on stumps. Our guide to epoxy flooring and polished concrete compares two hard wearing options for slab homes. Ask your installer about sealing edges and joins while the work is under way.
Fireplaces, vents, fans and downlights
An unused fireplace is often one of the biggest holes in a house. CSIRO recommends a fireplace damper to block airflow. Old exhaust fans can be covered over winter with a ventilation cover. Fixed wall and ceiling vents in older brick homes are another common leak.
Be careful here, because some vents are there for a reason. Sustainability Victoria warns that flueless gas heaters need a fixed amount of ventilation to clear combustion products. Open flued heaters need a supply of fresh room air. Fixed ventilation openings in these homes must not be blocked.
Older vented downlights can leak air into the roof space. CSIRO suggests replacing them with IC rated LED downlights, which can be covered by ceiling insulation. Ask a licensed electrician to handle the swap. Our guide on choosing the right lighting for your home covers other things to weigh up when you replace fittings.
Gas appliances and fresh air
A sealed home still needs fresh air. Council guidance says a completely airtight home is not desirable. Some ventilation removes odours, carbon dioxide and other contaminants. Sustainability Victoria adds that ventilation reduces condensation and damp.
If your home has internal gas appliances, take extra care. Sustainability Victoria says a licensed gas fitter should check them after draught proofing and before use. That includes flueless heaters, open flued heaters and internal open flued water heaters. It also advises having gas appliances serviced at least every two years.
Open windows on opposite sides of the house when the weather outside is mild. This gives you controlled fresh air without leaving gaps open all the time. Keep your heating and cooling gear in good shape as well. Our guide to cleaning air conditioner filters explains a simple job that helps it run well.
Do it yourself or call a professional
Door snakes, weather strips and sealant are all fair DIY jobs. They are sold at most hardware stores and need little more than scissors and a sealant gun. Start with the rooms you heat or cool the most. Then work outwards through the rest of the house.
Some states offer help with the cost. CSIRO notes that some states have rebates for professionally installed draught proofing. In Victoria, the Victorian Energy Upgrades program supports people who install certain draught proofing and weather sealing products. Check your state energy department for what applies where you live.
For more detail on finding and sealing leaks, see the Sustainability Victoria draught proofing guide. The CSIRO article on draught proofing a house covers the research on leaky Australian homes. Both are free to read and written for householders.
Frequently asked questions
Can a house be sealed too well?
Yes, it can. A completely airtight home is not desirable because some ventilation is needed. Fresh air clears odours, carbon dioxide and moisture that can cause condensation and damp.
Is draught proofing safe with a gas heater?
Flueless and open flued gas heaters need fixed ventilation, so those vents must stay clear. Sustainability Victoria advises having a licensed gas fitter check gas appliances after sealing and before use. It also suggests having them serviced at least every two years.
Where should I start?
Start with doors and windows, since they are the easiest to fix. A door snake and some weather strips can make a noticeable difference in a single room. Then move on to floors, vents and fireplaces.
Does draught proofing help in summer?
The gaps that leak warm air in winter also let hot air in and cooled air out. Sealing them can help your cooling work better. Pair it with good window shading on hot days.
This article is general information only. Rules and rebates differ between states and change over time, so check with your state energy department or a licensed tradesperson before starting work.
