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How to install sash window locks

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
Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. 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.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.