How to fit window restrictors

What are window restrictors?

Window restrictors are metal fittings or mechanisms attached to the inside of the window frame that limit how far a window can open. 

With a range of different types to choose from — each with its own benefits and disadvantages — it’s important to choose the right ones that suit your style of windows while remaining practical.

Types of window restrictors 

There are a variety of different restrictors to choose from and finding the right one that fits, is easy to use and is discrete goes a long way to achieving your dream windows.

The different types of window restrictors on offer include:

Concealed window restrictorsA small, metal guide rail is connected to a pin. As the window opens, the pin prevents the window from opening further when it reaches the end of the rail. This is the most common type of restrictor used on modern UPVC awning windows.

Cable window restrictorsA short cable links the window to the frame — preventing it from fully opening. It’s a quick and cost-effective way to add an additional security to any type of window.

Sash window restrictor — These are small mechanisms that are attached to the frame. A protruding piece of the mechanism rotates, allowing it to pivot over the frame, securing the window in place and adding extra security to older and modern windows.

Lockable restrictorsSimilarly to sash window restrictors, lockable restrictors come with a key and a locking mechanism to strengthen the restrictor to further deter criminal activity.

How to fit window restrictors

The most common window restrictor available is the concealed window restrictor as it provides many of the same benefits of other types while remaining discrete.

A concealed window restrictor can be fitted quickly and easily by following these simple steps as shown by the diagram below:

casement restrictor

A — Measure and fit the restrictor arm 

Using your hand to hold the restrictor arm in place, try a variety of positions along the side of the window fixture. When you reach a position where the restrictor arm closes in place smoothly, mark the top and bottom of the fitting and drill two pilot holes into the outer part of the window frame.

Hold the restrictor arm over the pre-set guide holes and drill screws through the restrictor arm and into the frame to secure the arm in place. Using your hands, check that the restrictor arm is tight enough at the base, but mobile at the pivot point — the restrictor arm should move at the pivot point with almost no effort and rebound back into place when the force is removed.


B — Fit the restrictor stud

Where the restrictor arm acts as more of a guide rail, the restrictor stud is the pin that connects the restrictor arm to the window.

Similar to the restrictor arm, the pin will also need positioning. Pull the window towards the fixed frame and mark the point where the restrictor arm naturally meets the window — this acts a guide to show you where the pin will sit when the window is closed and where to drill it in.

Place the pin mechanism onto the marked guidelines and drill some pilot holes in line with the pre-cut holes on the pin base. Drill some screws in tightly to secure the pin base to the frame.

C — Check the mechanisms work

Ones the restrictor arm is screwed in place, make sure the arm can still move freely at the pivot point. You can do this by giving it a quick wiggle with your finger while making sure the base is fixed in place.

As you pull the window back from the unlocked position, the pin should effortlessly glide into the groove on the restrictor arm. When unlocking the restrictor, you should be able to easily lift the arm away from the pin to access full range of motion.

Luckily, Core Sash Windows handle the entire process for you. Enquire today and get a free measurement and no-obligation quote.

Why do I need window restrictors?

There are many reasons home-owners might need or consider installing window restrictors.

These reasons include:

Improved securityA thief’s dream is an open window — they can be in and out quickly, steal your belongings and leave you feeling vulnerable. Almost all home insurance providers void policies if it’s later discovered the house was unlocked — whether it be a window or a door — so it’s vital home-owners take steps to bolster their security. A window restrictor lets homeowners draw fresh air into the home while deterring criminals from breaking in.

Child-safetyThe safety of children is paramount in any home and window restrictors play a pivotal role safeguarding them. Not only does it add an extra layer of protection against intruders but they prevent small children falling through them — making them a must-have for homes with children running around.

Allows control of air flowWhether it’s raining, windy or snowing, window restrictors let people get some fresh air into their homes while simultaneously protecting them from the elements. 

Legal reasonsHealth and safety laws ensure that vulnerable people are protected in public and personal spaces – so it’s important to check if you need them in your home or establishment to make sure your infrastructure is compliant with legislation.


Can you retrofit window restrictors?

Most types of window restrictors can be retrofitted — meaning they can be upgraded — but some can’t.

Before you look to retrofit existing window restrictors, double check with the manufacturer that they can be upgraded to a higher specification, otherwise you could do damage to your fixtures.

When should window restrictors be fitted? 

Preferably, window restrictors should be fitted on any window. 

Not only help home-owners regulate the temperature and airflow in their home — no matter what the weather – but they help to deter thieves and keep the occupants safe all year round.

Are window restrictors required by UK law?

Despite not being written into UK law, window restrictors are seen as the norm in homes and public establishments across the country. 

However, health and safety legislation compels some institutions to guarantee the safety of their occupants. For example, hospitals must have window restrictors to protect vulnerable patients and nurseries must have them to protect children. Highrise hotels must also have window restrictors to protect guests as vulnerable people and young children can also occupy these spaces.

Do window restrictors make your home safer?

Homes with window restrictors are almost certainly safer than homes without restrictors.

Insurance policies protect you from criminal activity that’s out of your control. Unfortunately, should a burglar gain access through an open window or door, a victim isn’t protected by their home insurance and their policy is void. 

Having restrictors mean that the door or window is not considered “open” — not only keeping your house safer but saving you the headache of navigating a home insurance claim.

Are window restrictors a fire hazard?

No, window restrictors are not a fire hazard, provided you have suitable and safe escape routes and a plan of action throughout the home. 

Although, they’re designed to be child proof and more difficult to open, a home with functioning fire alarms and a thorough exit plan will be safe regardless of whether a window restrictor is fitted or not.

Enjoy being warm and comfortable!

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