Sash Window Locks

This detailed guide will teach you everything you need to know from repairing, installing, securing and improving sash window locks. Here at SJB Sash Windows, we’ve learnt everything there is to the anatomy of a sash window and we want to share our extensive knowledge and expertise.

Due to the age of the sash window design, there are often myths that sash windows aren’t as secure as newer style windows. If anything, sash windows have stood the test of time for a reason. We’ll debunk these common myths throughout the guide.

Sash windows have been a popular option for hundreds of years and have even become a staple feature in period properties. We’ll enlighten on how best to look after your sash windows to get ultimate security.

1) What is a sash window safety lock?

A sash window safety lock is used to lock the sash of the window and therefore, prevent the window from opening.

Sash window safety locks are fixed to a vertical sliding sash window. It doesn’t matter whether the window is made from uPVC, timber or even aluminium, they will all use a sash window lock.

sash windows safety locks

2) What is a sash window?

A sliding sash window is a type of window where two sashes slide up and down within the frame. The top sash is the one closest to the outdoors; this will be in front of the lower sash. The bottom of the top sash will align with the top of the lower sash.

A more modern sash window will have two sash panels but only one of them will move. Usually, it will be the bottom sash that will slide up.

Older versions of the sash windows had a cord with weights to help open and close the window, but these are seen less now due to their repair process. Once the chord breaks you have to take the sash out of the frame in order to replace it.

Sash windows have been found in eras from Victorian, Georgian and Regency times. However, the design did change slightly through these periods.

sash windows london

3) What’s the difference between casement & sash window safety locks?

A casement window is held together by hinges that allow the sash window to swing open. Casement window locks usually act as a handle as well as a lock. To open the window you’ll have to turn the key or push the lock button and move the handle.

A sash window slides open vertically and not outwards like a casement window. New sash window locks are more commonly known as sash window fasteners. This does not act as a handle as it only de-restricts the window to allow it to open. To open the sash window you would need to slide it up or use a chord.

sash windows safety locks

4) Are sash window safety locks childproof?

Casement window locks are a lot harder for children to open as they require a key, turn and push approach; without a key, they simply can’t open the window.

Sash window locks only require you to turn and slide, while the sash windows are heavy and this may be hard, it’s not impossible for a child to do. You can buy sash window restrictors that require a key to open the window and therefore, have a childproof sash window.

5) How to open sash window locks

The most common type of fastener for sash windows is the Fitch fastener. It has a half circle shaped lever that slides into the catch. As the lever is turned towards the catch, it gravitates the windows together to create a seal between them.

However, to open sash window locks, you can pull the leaver from one side to the other and this will release it from the catch; just like in the image below.

top quality sash window safety locks in london

6) How to install sash window locks

Installing sash window locks is an easy D.I.Y task that even beginners can do. If you have a small sash window, you may only require one Fitch fastener to secure the window. But, bigger windows, such as the ones at the front of your house will often require one each size of the window.

Tools you’ll need to install the lock: Ruler, lock, pencil, power drill.

Step One: Place the lock on the sash window

The window will need to be in the closed position before you start. It’s best to take a ruler and measure the centre of the window so that your lock is central. If your sash window is large you may want to put one each side.

Once you have measured your central point mark it with a pencil (on both the upper and lower sash). The lock will come in two parts. The catch should be placed on the upper sash and the lever on the bottom sash.

sash windows lock installation
sash windows lock

Step Two: Drill pilot holes for the screws to be placed in the sash window frame.

You’ll need to pick up the pencil again and place it through the screw holes of the lock while placed on the frame. Remove the lock and you’ll be left with a pencil guiding of where to drill.

The correct drill size is easily distinguished, test out which ends fit through the lock holes and use the best fitting one. Once you’re ready, drill down into your pilot holes.

Place the fastener back over the holes and screw the screws into place. You may want to use a screwdriver for the back sash, as you’ll want to make sure you don’t damage the window. You can use the drill for the front piece.

Test your new sash fastener out, make sure it opens and closes as it should do and that it’s also secure.

sash windows lock

7) How to fix sash window locks

This will depend on what part of your fastener is broken. If the lever is broken or it has worn away and no longer secure, it’s easier to replace the whole fastener. The fasteners range in price but they are not typically expensive if you are replacing a few of them.

The sash window locks usually come as a pair and you may find it hard to find one part of the pair that matches the working part of your current fastener.

If the fastener is coming loose, you can always buy new screws or try moving it slightly over.

8) How to replace sash window locks

The main reason you may be looking to replace your sash window locks is because they have become loose. This may mean that your sash windows aren’t locking tightly and this will cause your windows to rattle or let in a draft.

Tools you’ll need: Screwdriver & new fastener.

Step One: Remove all of the screws.

You should be able to do this with a screwdriver, but you can use a drill if they are too tight.

Step Two: Remove the fastener.

Clear away any debris or flickers of paint that are lingering in the area. Make sure it is clear before placing the new fastener there.

Step Three: Place the new fastener where the old one was.

Simply put the fastener in the appropriate position and screw the screws into the existing holes.

There you have it, a brand new sash window lock.

9) Should you paint sash window locks?

If you want to repaint your sash windows, you may be tempted to leave the sash window locks on during. This can cause problems and decrease the security of your fastener.

You should remove the locks before painting the windows as the paint can cause the lock to not close securely. The paint will also scratch off over time, so it’s overall better for the appearance of your window too.

10) Are sash window locks safe?

If well maintained and properly locked, sash window locks will provide a good level of security. The most secure fastener is the Fitch sash window lock.

This is because the half circle catch is less vulnerable to attack due to it being hard to open these from the exterior side of the window.

A simple pivot catch can be knocked open by using a knife that is placed between the two sashes. A single screw catch could be easily knocked off by hammering a screwdriver between the two sashes.

Criminals may try and enter your sash windows by using a crowbar to pry open the lower sash window. This usually happens in timber windows that have been overpainted. Criminals can pierce through the paint, which leaves them with enough space to fit the crowbar.

If you’re painting your sash windows you should always make sure you sand them beforehand to avoid this.

Sash Window Installation

11) Further ways to improve your sash window security

Sash Stops

Sash stops are fitted on the upper sash and this prevents the sashes from sliding over each other. This, therefore, prevents them from opening the window.

There are two types of sash window locks for sash stops. You can either get protruding bolts that are removed with a key or bolts that are extracted just like with dual screws.

You can fit the sash stops 100mm above the top of the lower sash to enable the window to be opened a little for ventilation without the worry that someone can get through the window.

Top Quality Sash Window Restrictors

Dual Screws

Dual screws fit most sash windows and they offer added security to put your mind to rest. These sash window locks bolt through the top and bottom sash to stop the window from opening. The bolt can be removed with the key that will come included with the lock and this will allow the window to be opened.

Dual screws lock the sashes into place and avoid any sliding, even if the fastener is compromised.  Full bolts are slightly more expensive but they do provide more protection.

Best Sash Window Locks

 Double Glazing

As well as saving on your energy bills and blocking out noise, double glazing will also help protect your home from criminals.

Single glazed windows consist or around 3mm of glass which makes it easy to break. Double glazed glass is around 4mm thick and consists of two panels, nearly 3X more glass.

Thicker glass means it’s harder to break and therefore the appeal for criminals to break into your home decreases. Triple glazing is becoming increasingly popular due to its security increase and heightened benefits for the current climate.

Get your windows Installed by a Professional

Whilst it’s fine to change the sash window locks yourself, it’s better to get more detailed procedures done by professionals. Not only professionals, you should check out their credibility, reviews, social media and ensure they are on websites such as Trust Pilot or Check a Trade.

Making sure you get your sash window installation or sash window locks done by an accredited business means that you can rest assure your windows are safe.

SJB Sash Windows London

Ensure you service your sash windows & don’t put off repairs

If you’re having problems opening and closing your sash window, this is a safety concern. It’s likely that a cord inside the frame has become worn over time (if you have a chord). Some sash windows have spiral balances instead of cords and weights.

Wear and tear on the cord happens as it is such an integral part of your window. This means that at some point, your cord will no doubt need servicing.

The spiral balancers can also become worn and these may need repairing. Each balancer has a size and weight that is unique to your sash window.

You should get these repairs done straight away to ensure you’re secure and to also prevent further problems.

Sash windows have stood the test of time and these timeless windows can add character and value to your property. Take the proper security measures, replace your sash window locks when needed, take extra precaution by adding sash stops and you’re as secure as you can be.

Look after them, and they’ll look after you.