Complete Guide to Window Restrictors

Window restrictors are a simple but critical piece of hardware that limit how far a window can open. Whether you are a trade installer, landlord, facilities manager or DIY homeowner, choosing the right restrictor – and fitting it correctly – is vital for child safety, compliance with UK regulations and day‑to‑day usability.

This guide from Window Hardware Store explains UK legal requirements, the main types of restrictors, fire safety issues, installation methods and ongoing maintenance. It is written for both professionals and competent DIY users, with practical advice based on typical UK uPVC, aluminium and timber windows.

Throughout this guide you will find links to relevant products and categories, including our dedicated window restrictors section and specialist cable restrictors.

What is a Window Restrictor?

A window restrictor (also called a window limiter) is a mechanical device that limits the opening of a window sash. It is commonly used to:

Reduce the risk of falls from height, especially for children and vulnerable adults

Control ventilation without allowing a full opening

Comply with UK Building Regulations and health and safety guidance

Improve security by restricting how far an intruder can push a window open

Restrictors can be surface-mounted or concealed, key-lockable or permanently engaged, and are available for almost every window type used in the UK: uPVC casement, tilt & turn, timber sash, aluminium and steel windows.

Well-known manufacturers supplying the UK market include Yale, ERA, Mila, Avocet, Nico and Securistyle, alongside many specialist brands that focus on particular sectors such as healthcare and education.

1. Legal requirements

Understanding the legal and regulatory framework is essential, particularly for trade installers, landlords, social housing providers and those working in schools, care homes and hospitals. While domestic homeowners have more flexibility, it is still important to follow best practice to reduce the risk of falls and ensure insurance and warranty compliance.

Building Regulations for dwellings (England & Wales)

Several parts of the Building Regulations are relevant to window restrictors, even though they may not always name restrictors directly:

Approved Document K – Protection from falling

Approved Document B – Fire safety

Approved Document Q – Security (for new dwellings)

Approved Document K deals with the risk of people falling from windows. It states that where there is a risk of falling from windows more than 600mm above floor level (and a fall of more than 600mm externally), measures must be taken to prevent falls.

The guidance points towards either:

Providing a guarding or barrier, or

Limiting the window opening to a maximum of 100mm

In practice, the 100mm gap has become the standard reference for child safety. Many window restrictors are specifically designed to limit the opening to 100mm or slightly less when engaged.

For new build or replacement windows, especially in upper-storey bedrooms and living areas, it is common for specifiers to require either:

A restrictor that limits the opening to 100mm for normal use, with an override for cleaning or escape

A barrier or guard rail designed in accordance with Document K

Approved Document B (fire safety) introduces a second, sometimes conflicting requirement: certain windows must provide a suitable means of escape in case of fire. These are often called “egress windows” or “escape windows”. Any restrictor used on an escape window must be quickly and easily releasable without special tools.

This interaction between K (fall prevention) and B (fire escape) is explored in more detail in the fire safety section of this guide.

Scotland, Northern Ireland and local guidance

Scotland and Northern Ireland have their own technical standards, but the principles are similar:

Windows in locations where people could fall are either guarded, or opening is restricted

Escape windows must open to provide sufficient clear area for evacuation

Local authorities, housing associations and large landlords often have their own specifications or policies building on the national regulations. For example, many require child-safety restrictors on all windows above ground floor in family housing or HMOs.

Landlords, HMOs and the Housing Health and Safety Rating System (HHSRS)

Under the HHSRS, falls from windows are classified as a potential hazard. Local authority environmental health officers can require remedial work if windows present a significant risk, particularly in:

Houses in Multiple Occupation (HMOs)

Student accommodation

Temporary or supported housing

Fitting robust window restrictors is a common and often cost-effective way for landlords to manage fall risks. However, they must not compromise safe escape in case of fire and must be properly installed and maintained.

Healthcare, care homes and educational settings

The Health and Safety Executive (HSE) provides specific guidance on window restrictors in health and social care environments, where patients or service users may be especially vulnerable. A widely cited document is HSE’s “Falls from windows or balconies in health and social care,” which recommends that:

Window restrictors used to prevent falls should withstand a force of at least 350N (approximately 35kg)

Restrictors should be robust, tamper-resistant and not easily disabled by service users

Regular inspection and maintenance must be carried out and recorded

Many specialist restrictors used in hospitals and care homes are tested to BS EN 13126-5 or similar standards, which specify mechanical strength and durability requirements for safety devices limiting window opening.

Schools, nurseries and other educational buildings should also carry out risk assessments on windows accessible to children. In practice, this often leads to the use of lockable restrictors or restricted friction hinges on first floor and higher windows.

Relevant standards

A number of British and European Standards apply to windows and their safety devices:

BS EN 13126-5 – Building hardware: Hardware for windows and door height windows. Requirements and test methods for devices that restrict opening

BS EN 14351-1 – Windows and doors: Product standard, performance characteristics

BS 8213-1 & BS 8213-4 – Windows, doors and rooflights: Code of practice for design and installation

When choosing restrictors for commercial projects, public buildings or multi-dwelling developments, it is good practice to select products tested and certified to these standards, especially for child safety and vulnerable users.

Child safety and the 100mm rule

In the UK, most guidance relating to children and windows refers to a maximum opening of 100mm. This dimension is widely accepted as small enough to reduce the risk of a child slipping through an opening, but it is not a guarantee against all accidents.

Key child safety considerations include:

Limiting opening to 100mm or less in normal use for windows above ground floor

Ensuring restrictors are strong enough to resist force from a child leaning or pushing against the window

Using key-lockable devices where there is a high risk of tampering, but balancing this with the need for quick escape

Educating occupants about the purpose of the restrictors and the risks of disabling them

For domestic homes, particularly with young children, products such as key-lockable cable restrictors and restricted friction hinges from brands like Yale, ERA, Mila and Avocet are widely used.

2. Types of restrictors

There is no single “best” window restrictor; the right choice depends on the window type, frame material, usage pattern and regulatory requirements. Below are the most common categories used in UK homes and commercial buildings.

Cable window restrictors

Cable restrictors are one of the most versatile and popular retrofit solutions. A tough steel cable, usually coated in white or coloured plastic, connects the window frame to the opening sash. When the cable is engaged, the window can only open as far as the cable allows (often 100–150mm). Many models are key-lockable.

Typical features:

Surface-mounted body fixed to the frame

Cable end fixed to the sash, generally with two or more screws

Key-operated lock to engage or disengage the restrictor

Screw-on or concealed fixings for aesthetics and security

Advantages:

Suitable for most materials: uPVC, timber, aluminium, steel

Relatively easy to retrofit without disturbing existing hinges

Flexible positioning on the frame

Available in a wide range of finishes (white, brown, anthracite grey, chrome, brass, black, etc.)

Ideal for homes, rented properties, offices and light commercial use

Considerations:

Quality varies; look for cable restrictors tested to relevant standards and rated for at least 350N where child safety is critical

Incorrect positioning or poor fixings can reduce effectiveness

Keys must be managed carefully in shared or rented properties to avoid blocking escape routes

Recognised UK brands include Yale, ERA, Mila and Avocet, many of which are available in our cable restrictors range.

Restricted friction stays and safety hinges

On many modern uPVC and aluminium casement windows, the restriction function is built directly into the friction stay (the hinge). These are often called restricted friction hinges, safety stays or safety restrictors.

Typical designs include:

Side-hung friction hinges with a built-in restrictor that engages automatically at around 100mm opening

Top-hung hinges with limited initial opening, sometimes combined with a cleaning position

“Easy clean” or “egress” hinges that open wide for escape and cleaning once a button is pressed

Advantages:

Very neat – no additional visible hardware

Automatically engaged when window opens

Good for new-build and full window replacement projects

Often tested as part of a complete window system for strength and durability

Considerations:

Retrofitting can be more involved, as hinges need to be replaced and sash realigned

Frame must be compatible with the new hinge stack height and geometry

Release mechanisms vary; installers must ensure occupants understand how to operate them in an emergency

Mila, Nico, ERA, Securistyle and Avocet all supply restricted and egress friction stays for UK casement windows.

Surface-mounted restrictor arms

Surface-mounted restrictor arms are rigid metal bars or arms fitted to the sash and frame. They normally pivot or slide in a channel and feature a stop position to limit opening. Some have multiple detent positions for different ventilation settings.

They are particularly common on:

Timber casement windows

Older aluminium windows

Commercial aluminium or steel windows

Advantages:

Robust and long-lasting, with minimal moving parts

Good for large or heavy sashes where a cable restrictor might be less suitable

Can be specified with tamper-resistant fixings for public buildings

Considerations:

More visible than concealed or hinge-based restrictors

Careful positioning is needed to avoid clashing with existing stays or handles

Some models are not ideal for domestic settings if aesthetics is a priority

Concealed restrictors and sash jammers

On some window systems, especially premium aluminium or timber products, restrictors can be concealed within the frame or sash. These may take the form of:

Concealed sliding bolts that engage with slots in the frame

Drop bolts or pins that limit movement

Special locking stays integrated into the sash profile

Advantages:

Excellent aesthetics – little or nothing visible when the window is closed

Can be designed to work perfectly with the specific window system

Often strong and durable

Considerations:

Mainly used on new windows, not easy to retrofit

Operation and release mechanisms vary widely; good labelling and user instruction is essential

Replacement parts may be system-specific and not interchangeable

Cord, chain and limiter devices for tilt & turn windows

Tilt & turn windows require different approaches because of their dual opening modes. Specialist restrictors control the tilt opening, the turn opening, or both. Common devices include:

Limiters integrated into the tilt & turn gearing

Surface-mounted restrictors that limit opening in turn mode

Detachable cords or chains that fix between sash and frame

Correct configuration is particularly important in high-rise buildings and apartments, where tilt & turn windows are often used and fall risk is significant.

Sliding sash window restrictors

Traditional timber sliding sash windows, and modern uPVC vertical sliders, use specific types of restrictors and stops:

Sash stops / sash restrictors – threaded stops that screw into the sash stile and engage with a receiver in the frame to limit travel

Keyed sash locks – devices that lock the two sashes together at a partially open position

Cord or cable devices – less common but sometimes used as an additional safety measure

Advantages:

Allow the sash to be locked in a slightly open position for ventilation

Discreet and often sympathetic to period aesthetics

Available in a range of finishes to match sash furniture (brass, chrome, satin chrome, etc.)

Considerations:

Installation requires precise positioning for smooth operation

Threaded stops must be aligned carefully and fitted into solid timber

Some traditional designs provide security but are not tested as child-safety restrictors; always check product specifications

Specialist restrictors for doors and Juliet balconies

While this guide focuses on windows, many of the same principles apply to door restrictors and balcony protections. For example:

Inward or outward-opening balcony doors may use restrictor arms or stays

French doors in upper-storey apartments may require limiters to prevent excessive opening

Juliet balcony doors with low sill heights should be risk-assessed in the same way as large windows

In such cases, high-strength restrictors or purpose-designed door limiters are often preferred, especially in multi-occupancy buildings.

3. Fire safety considerations

Any device that limits the opening of a window must be considered in the context of fire safety. The Building Regulations require that in certain rooms, windows serve as an emergency escape route. A poorly selected or installed restrictor could compromise this function.

Escape windows and minimum opening sizes

Approved Document B sets out criteria for windows that are to be used as emergency exits in dwellings. While the exact details can vary by revision, typical requirements include:

Clear opening area of at least 0.33m²

Minimum clear opening dimension (height and width) of at least 450mm

Bottom of the clear opening no more than 1100mm above the floor level

Where a window is designated as an “escape window,” any restrictor used must allow rapid opening to the full escape dimension without the need for special tools. In practical terms this means:

No permanently fixed restrictor that cannot be overridden

Release mechanisms should be obvious and simple

Keys, if used, must be readily accessible to occupants at all times

Restrictors with emergency release

Many modern restrictors are specifically designed to balance child safety with fire escape needs. Common solutions include:

Restricted friction hinges with a push-button or lever that allows full opening for escape

Cable restrictors with a key-operated lock that completely releases the cable when unlocked

Surface-mounted arms with a manual release catch

When selecting products for rooms with designated escape windows, look for features like:

Clearly marked release buttons or levers

A single, intuitive action to override the restriction

Manufacturer documentation confirming suitability for use on escape windows when correctly installed

Installers should also ensure the operation of the restrictor does not make it difficult or confusing for occupants in a smoke-filled or low-visibility situation.

Key management and escape routes

Key-lockable restrictors are very popular for child safety and security, but they introduce an extra layer of responsibility. Poor key management can mean:

Occupants cannot find the key quickly during a fire

Escape windows are effectively disabled

Firefighters cannot access certain windows from inside

Best practice for key management includes:

Keeping keys in a clearly visible place near each restricted window (but out of children’s direct reach)

Using colour-coded or labelled keys for different restrictors in larger properties

Avoiding locking escape windows in a way that cannot be overridden internally without a key

Including window key locations in fire evacuation plans

In HMOs, care homes and other managed buildings, key management should be written into fire safety procedures and staff training.

Balancing child safety and means of escape

In many family homes, especially in flats and upper-storey bedrooms, there is tension between preventing falls and ensuring quick escape. To strike the right balance:

Use restrictors that automatically limit opening in day-to-day use

Ensure the restrictor can be overridden quickly by an adult without tools

Position release mechanisms so they are accessible to adults but not easily operated by small children

Avoid over-reliance on furniture placement (e.g. keeping beds away from windows) as the sole safety measure

Trade installers should discuss these issues with customers at survey stage, especially when working on children’s bedrooms, loft conversions and flats above ground floor level.

Common compliance mistakes

Some of the most frequent fire-safety errors involving window restrictors include:

Fitting non-releasable restrictors on escape windows

Using DIY or improvised devices (chains, homemade stops) that jam or fail

Installing restrictors that reduce the effective escape opening below Building Regulations requirements

Painting over release mechanisms on timber windows, making them difficult to operate

Failing to explain operation of egress hinges and restrictors to the homeowner or facilities staff

In all cases, if you are unsure whether a particular window serves as an escape route, consult the original building documentation, a qualified fire risk assessor or the relevant Building Control guidance before finalising the restrictor choice.

4. Installation methods

Correct installation is crucial for both safety and longevity. Poorly fixed restrictors can fail under load, leave windows draughty, or cause the sash to bind. This section covers general principles and specific trade tips for common window types.

Planning and measuring

Before drilling any holes or ordering hardware, take a few minutes to plan:

Identify the window type: uPVC casement, top-hung, tilt & turn, timber casement, sliding sash, aluminium, etc.

Confirm whether the window is designated as an escape window

Check existing hardware: hinges, stays, handle position, trickle vents

Measure the frame and sash dimensions accurately in millimetres (mm)

For surface-mounted restrictors (like most cable devices):

Measure at least 50–100mm in from the sash corner to find a solid fixing point

Avoid fixing into gasket areas or thin plastic; aim for reinforced sections on uPVC frames where possible

On timber, ensure you are fixing into sound, solid wood – avoid rotten or split sections

Common measuring tasks include:

Frame width and height (inside the reveal) in mm

Face width of sash and frame where the restrictor will sit (often 30–60mm on uPVC casements)

Wall thickness of timber sections to select correct screw length (for example, 4.0 x 25mm or 4.0 x 30mm wood screws)

Trade tip: When surveying for multiple windows in a block of flats or care home, record each window’s location, type and intended restrictor model. This avoids confusion and returns to site.

Tools and fixings

For most DIY and trade installations you will need:

Drill/driver with suitable bits (2.5–3mm HSS or wood bits for pilot holes; Pozi or Torx bits for screws)

Measuring tape marked in millimetres

Pencil or fine marker

Screws appropriate to frame material (typically 3.9–4.3mm diameter, 16–30mm length)

Silicone or frame sealant (optional, for external fixings)

Using the correct pilot hole size is essential, especially in timber and uPVC, to prevent splitting or stripping. As a guide:

For 4.0mm wood screws in softwood: 2.5–3.0mm pilot diameter

For 4.0mm screws in hardwood: 3.0–3.2mm pilot

On aluminium, use self-tapping screws or drill appropriate pilot holes as specified by the hardware manufacturer.

Fitting cable restrictors to uPVC windows

Cable restrictors are commonly retrofitted to uPVC casement and tilt & turn windows. A typical installation on a side-hung casement window would proceed as follows:

Open the sash to a comfortable working position (200–300mm).

Hold the restrictor body (lock housing) against the fixed frame, usually on the handle side, around 100–150mm below the top corner.

Ensure there is enough flat surface on the frame to take the full footprint of the restrictor body.

Mark the fixing holes with a pencil.

Drill pilot holes (e.g. 2.5–3mm) into the uPVC, being careful not to drill through to the outside. Typical screw length is 16–20mm for most frame sections.

Fix the restrictor body using the supplied screws, checking it sits square.

With the cable latched into the body, extend it to the sash and choose a fixing point that will give the desired restricted opening (often around 100mm).

Mark and drill pilot holes in the sash at this point.

Fix the cable-end bracket to the sash using suitable screws.

Test the window fully: check that with the cable engaged, the opening is limited; with the lock disengaged, the window opens freely without the cable binding.

Trade tips for uPVC:

On reinforced frames, aim to fix into the reinforced zone where possible. A magnet or manufacturer’s section drawing can help identify reinforcement position.

Avoid overtightening screws into uPVC to prevent stripping or distortion.

If the sash is very narrow, check that the restrictor body does not interfere with gasket compression when closed.

Fitting cable restrictors to timber windows

The process is similar to uPVC but with additional care about timber condition:

Check for rot, loose paint and soft areas; do not fix into damaged timber.

Lightly sand and clean the fixing area if needed.

Use appropriate wood screws (often 4.0 x 25mm or 4.0 x 30mm) and drill correct pilot holes.

On old sash windows, avoid fixing into very thin glazing bars – choose frame stiles or thicker rails.

For painted windows, consider treating screw holes with a small amount of timber preservative before fixing, especially on exposed external faces.

Installing restricted friction hinges

Replacing standard friction stays with restricted or egress hinges is more complex than fitting surface restrictors. It is typically a trade job, but competent DIYers can tackle it with care.

Measure the existing hinge length (commonly 300mm, 400mm, 450mm or 600mm).

Note the stack height (distance from bottom of hinge to centreline of pivot). Most uPVC casements use 13mm or 17mm stack height hinges.

Choose replacement restricted hinges matching length, stack height and handing (e.g. side-hung left/right, top-hung).

Support the sash securely (e.g. with packers or a helper) before removing hinge screws.

Unscrew and remove the old hinges from both sash and frame.

Offer up the new hinges in the same position. Some adjustment to fixing holes may be necessary, but avoid weakening the sash or frame by over-drilling.

Fix the hinges to frame and sash using appropriate screws (stainless steel recommended for longevity).

Close and open the window slowly to check for smooth operation and correct engagement of the restrictor and release feature.

Trade tip: When upgrading multiple windows in a property, fitting one first and fully testing the restrictor operation before proceeding with others can save time if adjustments are needed.

Installing restrictors on aluminium and steel windows

Aluminium and steel frames are usually thinner and harder than uPVC or timber, so they require different fixings:

Use self-tapping screws or machine screws into existing threaded holes or inserts where provided.

Drill pilot holes with HSS or cobalt bits, using a slow speed and cutting fluid to avoid overheating.

Deburr holes to prevent sharp edges damaging cables or restrictor arms.

Where very slim sections make direct fixing difficult, consider specialist clamp-on hardware or consult the window manufacturer.

In commercial curtain walling or large-span aluminium systems, restrictors and limiters are often specified at design stage; retrofitting should follow the system supplier’s guidance.

Sliding sash restrictor installation

For vertical sliding sash windows, threaded sash stops are a common solution:

Decide the maximum opening you want, typically 100–150mm above the cill for child safety while allowing ventilation.

Raise the lower sash to this position and mark the meeting point of sash and frame.

Drill a pilot hole into the side stile of the sash, keeping parallel to the glazing.

Fit the threaded insert (if supplied) or screw the stop directly into the timber, depending on the product design.

Repeat on the other side for balanced support.

Test operation: the sash should stop against the restrictors and lock in place; when the stops are removed or retracted, the sash should travel freely.

Always follow the manufacturer’s instructions; incorrect positioning can leave the sash skewed or put excessive strain on cords and balances.

DIY vs professional installation

DIY installation is usually appropriate for:

Simple cable restrictors on domestic uPVC or timber windows

Fitting restrictors where no critical fire escape or regulatory issues are involved

Replacing like-for-like existing restrictors

Professional installation is strongly recommended for:

Healthcare, care homes, schools and other high-risk environments

Windows forming part of a designated escape route

Commercial aluminium systems and curtain walling

Large or heavy sashes where mishandling could cause damage or injury

Trade installers should document their work, including the type of restrictor fitted, fixing method and any deviations from standard details. This is particularly important for landlords, housing associations and commercial clients.

5. Maintenance

Like all moving hardware, window restrictors need periodic inspection and maintenance. Neglect can lead to failure, increased risk of accidents, or difficulty operating the window in an emergency.

Routine inspection

For domestic properties, an annual check is usually sufficient. In higher-risk environments such as care homes, hospitals and HMOs, inspections may be required quarterly or even monthly under internal policies.

During inspection, look for:

Loose screws or fixings

Frayed, kinked or cut cables on cable restrictors

Cracks in plastic housings or covers

Stiff or seized hinges, especially restricted friction stays

Signs of tampering or deliberate damage (common in student or institutional settings)

Paint build-up around moving parts on timber windows

Any restrictor that shows signs of damage or does not function smoothly should be repaired or replaced immediately.

Cleaning and lubrication

Keeping restrictors clean and lightly lubricated will extend their life and ensure reliable operation.

Use a soft cloth and mild detergent to clean surfaces; avoid aggressive solvents that might attack plastic casings.

For metal hinges and arms, apply a small amount of light machine oil or silicone spray to pivot points. Wipe off excess to prevent dirt build-up.

Do not oil key cylinders; instead, use a specialist graphite or PTFE spray if needed.

On coastal or highly exposed sites, consider more frequent cleaning to remove salt deposits.

Trade tip: When carrying out annual window servicing, include restrictors on the checklist along with handles, hinges and locks. This is often an add-on service opportunity for installers.

Testing function and load capacity

As part of routine maintenance, test each restrictor:

Open the window until the restrictor engages and check that opening stops positively at the intended point.

Apply moderate pressure to the sash (simulating a person leaning) to ensure the restrictor holds firm without undue flex.

Operate any release or override mechanism to confirm it works smoothly and quickly.

In settings where HSE guidance applies (such as health and social care), some organisations carry out periodic load tests or checks with a force gauge to verify ongoing mechanical strength, particularly for older devices.

When to replace a restrictor

Replace restrictors immediately if you observe any of the following:

Frayed, broken or visibly weakened cables

Cracked or broken housings that expose internal mechanisms

Fixings that will not tighten properly due to stripped holes or damaged frames

Release buttons or keys that jam or fail intermittently

Corrosion on metal components, especially on coastal properties

When upgrading, consider using higher-specification products, for example moving from an unbranded cable restrictor to a tested model from Yale, ERA, Mila or Avocet. Check our window restrictors section for options tested to current standards.

Troubleshooting common issues

Problem: Window will not close fully after fitting a restrictor

Check whether the restrictor body or cable bracket is fouling the sash or gasket when closed.

Ensure screws are not standing proud and catching on the opposite frame.

Verify that the restrictor has not been mounted too close to the hinge side, causing binding.

If necessary, refit a few millimetres further away from the corner or use packers to adjust alignment.

Problem: Restrictor does not engage, window opens fully

Confirm the cable or arm is correctly attached at both ends.

Check internal mechanisms: on some models the lock must be turned to the “locked” position for the restriction to work.

Look for worn or broken internal parts; if present, replace the restrictor.

Problem: Key lost for a lockable restrictor

Identify the make and model; replacement keys may be available from the manufacturer or supplier.

In an emergency (e.g. immediate need for escape), it may be necessary to remove the restrictor by unscrewing it, provided this can be done safely.

Once resolved, consider a key management strategy to prevent recurrence.

Problem: Children or occupants defeating the restrictor

Review the type of restrictor used; some basic models are easier to bypass.

Consider upgrading to tamper-resistant models designed for institutional settings.

Reinforce education about the purpose of the restrictors, particularly with older children and teenagers.

Record keeping for landlords and institutions

For landlords, housing associations, schools and care providers, good record keeping around window restrictors is essential:

Log the type, location and installation date of each restrictor

Record inspection and maintenance dates, including any repairs or replacements

Note any incidents or near-misses involving windows and the action taken

These records support compliance with HHSRS, HSE guidance and fire safety regulations, and can provide important evidence in the event of an incident.

Choosing the right restrictor from Window Hardware Store

With many designs, finishes and performance levels available, selecting the right restrictor can feel complex. Focusing on a few key questions will help narrow down suitable options from our window restrictors range:

What is the frame material: uPVC, timber, aluminium or steel?

Is the window an escape route according to Building Regulations or your fire risk assessment?

Is the main concern child safety, security, ventilation control, or a mix of these?

Are you fitting in a domestic, rented, commercial, educational or healthcare setting?

Is this new-build/new-window installation or a retrofit upgrade?

For many domestic retrofits on uPVC casements, a high-quality key-lockable cable restrictor from a recognised brand (Yale, ERA, Mila, Avocet) provides a robust and cost-effective solution. For new windows, restricted friction stays or system-specific safety devices may be preferable.

If you require guidance for a particular project type – for example, care homes, schools, or a large block of flats – consult your fire risk assessment and local regulations, then match products that are tested and rated accordingly.

By understanding the legal context, knowing the available hardware options, and following best-practice installation and maintenance techniques, you can ensure that your windows provide safe ventilation, effective fall protection and compliant escape routes for years to come.