How to seal up gaps and cracks

If your home has gaps and cracks, general caulking to seal these up can reduce air leakage by 26%.

Gaps and cracks around window and door frames, between skirting boards and walls or floors, and between floor boards can all contribute to unwanted draughts and unnecessarily high energy bills. Sealing them up is a relatively easy task that you can do yourself, without the help of an expert.

How to seal up gaps and cracks

Note: If your home has gas appliances, please read our warning (below) before proceeding.

Step 1: Getting started

Identifying areas that need to be sealed up involves a thorough examination of all the walls, doors and windows around your house. Look for areas where light enters and feel for draughts here – in skirting boards, floorboards, door and window frames, architraves, cornices, and inside and around cupboards. If you are renovating, ensure that the joins between building elements are sealed too.

Step 2: Fixing the problem

Large gaps around doors and windows may require carpentry work to make the gaps smaller. A caulking ‘gun’ can be used for smaller gaps. Silicone sealants are water resistant and should be used in areas exposed to the weather. Expandable foam fillers are suitable for larger gaps or holes. Caulking products are available from your local hardware store in clear or white, and some can be painted over.

Like many jobs around the house, sealing up gaps and cracks relies on good preparation of the surfaces to be sealed. Always make sure the surfaces are clean and dry, and don’t forget to gently sand any painted surfaces, as this will allow the sealant to work better.

Tools needed

  • Caulking gun
  • Caulking compound or sealant
  • Cleaning cloth and sandpaper, to thoroughly clean and prepare surfaces before sealing them


Special care needs to be taken in houses which have internal gas appliances, especially houses which have flueless gas heaters, a gas heater installed in a chimney or an open flued gas heater.

All flueless gas appliances require a certain amount of fixed ventilation to expel the products of combustion from the home and operate safely. Open flued gas heaters – which draw combustion air from the room in which they are located – require a supply of fresh room air to operate safely.

Fixed ventilation openings required for flueless and open flued gas heaters must not be blocked.

If you undertake draught sealing in your home and you have these types of heating, or other indoor gas appliances (e.g. internal open flued gas water heaters or ducted heaters), you should get a licensed gas fitter to check the safe operation of the appliances before they are used.

It is recommended that you have your gas appliances serviced at least every 2 years. Energy Safe Victoria provides further information on the safe operation of gas appliances.

More information

If you need to know how to seal up other areas around the house, found out how in the following guides: