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Person using a cordless drill to drill a hole in a sash window frame

Overview

Installing a lock on a double hung sash window is easy and a great way to protect your home. You can open the window from the inside but would-be intruders can't open it from the outside. We'll show you how to centre and fit the lock in just a couple of steps. We have used a swivel lock for this demonstration, but you can also use a key lock.

Steps

1Position the lock on the sash window

Before you start, close the window. Take your ruler and measure the width of your window. Mark the centre of the window frame with your pencil where the upper and lower windows meet. Centre the lock/fastener over the mark. The lock comes in two parts, so place the back piece on the top sash and the front piece on the bottom sash.
Window lock positioned on a sash window

2Drill in pilot holes for the screws in sash window frame

Take your pencil and mark out the screw points through the holes of the lock. Next, take away the lock and drill some pilot holes into those marks, using your power drill. Make sure that you choose a drill bit that is the size same size as your screws.
Person using a cordless drill to drill a hole in a sash window frame

3Screw the sash window lock in place

Place the fastener back over the holes and screw it into position. To protect the glass, use a screwdriver for the back piece of the fastener. And finally, use your drill with the screw bit for the front piece. When you're done, open and close the window to make sure the fastener is working properly.

Person using a cordless drill to screw a sash window lock in place

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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. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.