How to seal gaps in doors and windows

Can you see daylight under your closed front door? Or do your curtains move even when the windows are closed? Gaps around doors, windows, floorboards and vents let in icy breezes, keeping your home’s temperature low and energy bills far higher than they should be. Read on to find out how to close those gaps and reduce your energy bills.

Bunnings magazine, April 2020

Find the leaks

“A clear sign that your home isn’t draught proof is drastic fluctuations in temperature in relation to the outside climate,” says Matthew Menichelli, director of Elevate Building Group.

A thermal imaging camera, if you can get access to one, can help to find the leaks around your home, but otherwise a good trick to locate gaps is to burn an incense stick near potential draught sites and see where the smoke goes.

Watch it: How to winterproof your home

Assess the exits

“The first place to start on leaks is your external doors,” Matthew says. “There’s always clearance in the door margins so that the door swings freely, and if there is no weather seal on the doorjamb, this is the number-one culprit of temperature loss in a home. Windows are a close second.”

You can use a door snake to keep draughts out, but a more efficient and permanent solution is to attach a door seal to the bottom of the door. You may need to cut it down with a hacksaw to fit your door and, if it comes with an adhesive backing, it’s worth reinforcing this with screws; pre-drill the holes using a drill bit one size down from the screws.

Watch it: How to seal a door

There’s a great variety of door seals available – including roller, PVC strip, storm proof, brush and auto lift – so you can choose the one that’s best for your situation.

Adhesive weather strips are a quick and easy fix for leaking doors and windows. Clean (and sand if necessary) the area you need to attach it to, cut the strip to the right length, remove adhesive backing and simply smooth it around the door and window frames. Ensure you have the right thickness – too thin and draughts will still get through, too thick and your windows and doors won’t close properly.

Cover up the cracks

Some homes have unfortunate gaps in their floorboards and skirting that are an open invitation to winter chill. There can be very small gaps where the skirting board and floor meet. By silicone sealing such gaps, the silicone, due to its flexibility, allows the natural movement in the timber while maintaining a sealed gap, reducing unwanted airflow,” says Chris Knierim.

“Floorboards are another area where air leakage can occur, so sealing the joints between the boards and installing insulation underneath the floor between the floor joists is a good preventative measure against unwanted draughts,” adds Chris.

Try a filler such as Selleys No More Gaps between the boards and use a caulking gun to seal the gaps between floor and wall. For bigger gaps, use expanding polyurethane spray foam. If you can access underneath the floor – as in a suspended timber floor – check the state of the insulation; many homes feature insulation that has been poorly installed and might be sagging and letting in cold air.

If there’s no insulation at all, installing batts in a suspended timber floor is an achievable DIY job. But if you can’t access under the floor or need extra cosiness indoors, don’t underestimate the warming effect of a plush rug.

Cables and pipes are often the culprits of wayward draughts. Check the points where the cables and pipes exit the house and fill any gaps with caulk or foam.

Various door seals, draught stoppers and insulation to help seal gaps in doors and windows.

Remember chimneys and vents

“Chimneys are often overlooked when it comes to insulating, partly because they’re being used during the winter months,” says Matthew. But when theyre not in use, consider installing a foam draught stopper and seal them up.

Fixed ceiling and wall vents are often a feature in older homes and can be a source of considerable draughts. You can try covering them with cardboard or clear contact for an instant temporary fix or, for a more permanent solution, replace them with closable vents.

Roof access hatches and manholes can also leak cold air, which is where adhesive weather strips come in handy again. Fix these or air seals around the hatch and insulate the upper side by fixing rigid insulation to it.

A word of warning

Don’t make your home completely airtight. “When creating an airtight home, it’s important to install ventilation systems to provide controlled natural air into the home,” says Chris. This is especially important if you have gas heaters or appliances, and to avoid possible build-up of VOCs (volatile organic compounds) that can emit from products such as new carpets and furniture, building materials and household cleaners.

If you’re not sure how much you can safely seal – especially when covering vents – seek help from a professional.

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Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.
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