Complete Guide to Window Hinges

1. Friction hinges explained

What are window friction hinges?

Modern UK casement windows, especially uPVC and many aluminium systems, use friction hinges rather than traditional butt or parliament hinges. Friction hinges are slim, stainless steel scissor mechanisms that control how the sash opens and closes, while providing enough resistance (friction) to hold the window in position without the need for separate stays.

On uPVC windows, these are often called “Espagnolette friction hinges” or simply “friction stays”. They are the standard hinge you will find on most double glazed casement windows fitted in the UK in the last 25–30 years.

You can view typical products in our window hinges category and dedicated friction hinges section.

Key components of a friction hinge

Although designs vary slightly between manufacturers such as Yale, ERA, Mila, Avocet, Nico and Securistyle, most friction hinges share the same core components:

Track: The long stainless steel bar fixed to the window frame.

Arm: The scissor-shaped part that attaches to the sash and slides within the track.

Pivot rivets: Fixed points around which the arms rotate.

Friction pads: Nylon or polymer pads that create the adjustable resistance.

Friction screw: A small screw (often a pozi or hex head) used to tighten or loosen the friction.

Stack (or stack height): The vertical offset between sash locating point and frame track (e.g. 13 mm or 17 mm).

End cap or locator: Helps position the sash correctly when closed and can include an integral weather seal stop.

How friction hinges work

When you open a friction-hinged window, the sash is guided by the scissor arms along the track. The friction pads press lightly against the track, creating resistance. This:

Prevents the sash from slamming in the wind.

Allows you to leave the window partially or fully open without using a separate stay.

Helps maintain airtightness and compression on the seals when the window is closed.

The friction level can be adjusted by gently tightening or loosening the friction screw on each hinge. For heavier sashes or windy locations, a slightly higher friction setting is often required.

Types of friction hinges

Different hinge designs are used to achieve various opening actions and to comply with Building Regulations. The main types used in UK domestic and commercial windows are:

Standard casement friction hinges

These are the everyday hinges used on top-hung and side-hung uPVC, aluminium and timber windows. They generally open to around 60–70 degrees and are available in various lengths, most commonly:

200 mm (8") – Small fanlights or narrow top-hung sashes.

250 mm (10") – Small to medium casements.

300 mm (12") – Standard side-hung and top-hung sashes.

400 mm (16") – Larger side-hung or top-hung sashes.

600 mm (24") – Very tall or heavy top-hung sashes, often on commercial or high-rise buildings.

Standard friction hinges are suitable where:

There are no specific fire escape requirements.

No restricted opening is needed beyond what the hinge naturally provides.

Access for cleaning can be achieved from inside or outside without a special egress function.

Egress hinges (fire escape hinges)

Egress hinges, often referred to as fire escape hinges, are specially designed friction hinges that allow the sash to open in such a way that occupants can climb out in an emergency. They are primarily used on side-hung windows in bedrooms and habitable rooms, where Building Regulations require a means of escape.

These hinges open wide and usually incorporate a mechanism that moves the sash clear of the frame, increasing the clear opening width. Many egress hinges also have an integral easy-clean position, allowing the sash to slide towards the centre of the opening for safe cleaning of the outside glass from indoors.

You can explore typical options in our window hinges and egress hinge ranges from brands such as Yale, ERA and Mila.

Easy-clean (egress & easy-clean combined) hinges

Most modern egress hinges fitted to uPVC windows are of the “egress easy-clean” type. They have two key actions:

Fire escape position – The sash opens to around 90 degrees and moves away from the frame reveal to create a large escape aperture.

Easy-clean position – By pressing a simple button or tab, the sash can slide along the hinge track. This pulls the hinge side of the sash towards the centre of the opening, making the external face of the glass accessible from inside the property.

These combined hinges make it easier for installers and homeowners to comply with both fire escape and safe cleaning requirements in one product.

Restricted hinges and safety stays

In certain applications, such as high-level windows, windows above ground-floor level in blocks of flats, or where child safety is a concern, restrictor mechanisms are required to limit the initial opening. These may be:

Built-in restrictor friction hinges – with a small catch that limits opening to around 100 mm until intentionally released.

Separate restrictor stays – add-on devices installed alongside standard hinges to restrict opening.

These are often used in conjunction with egress hinges to provide day-to-day safety while still allowing full escape opening when deliberately released by an adult.

Top-hung vs side-hung orientations

Friction hinges can be used in two main arrangements:

Top-hung – Hinges are fitted along the top edge; the sash swings outwards from the bottom.

Side-hung – Hinges are fitted on the left or right side; the sash swings outwards like a door.

Fire escape and egress requirements generally apply to side-hung windows, because top-hung windows rarely give adequate clear openings for escape routes, especially when restricted by stays or structural reveals.

Materials and corrosion resistance

Because friction hinges are exposed to the elements, corrosion resistance is critical. Most quality hinges are manufactured from stainless steel, commonly grade 430 or 304, with a protective passivation finish. On coastal properties or very exposed sites, upgrading to 316 grade or enhanced corrosion-resistant finishes can substantially extend hinge life.

When selecting hinges from brands like Avocet, Nico or Securistyle, always check the stated corrosion rating (e.g. BS EN 1670 Grade 3 or Grade 4) and consider your site conditions.

2. Stack heights

What is stack height?

Stack height is a crucial measurement when replacing or specifying friction hinges. It refers to the vertical distance between the frame fixing surface and the sash locating surface of the hinge. In simple terms, it is the amount that the sash sits off the frame when the window is closed.

The stack height affects:

How tightly the sash compresses against the weather seals.

How the sash lines up with the frame (reveal alignment).

Whether the sash will bind on the frame or leave visible gaps.

Choosing the wrong stack height can cause draughts, water leaks, difficulty closing the window or even glass breakage due to strain.

Common stack heights in the UK

Most uPVC and aluminium casement windows in the UK use one of two standard stack heights:

13 mm stack – Sometimes called “low stack” or “standard stack”. Very common on many uPVC systems.

17 mm stack – Often referred to as “high stack”. Used where a deeper offset is required between sash and frame.

Less commonly, some specialist systems and timber profiles may use other stack heights (such as 9 mm or 22 mm), but 13 mm and 17 mm cover the majority of modern domestic installations.

Why stack height matters for replacements

When replacing an existing set of friction hinges, it is usually essential to match the original stack height. If you fitted a 17 mm hinge where a 13 mm hinge was originally used, the sash would sit 4 mm further away from the frame in the closed position. This can result in:

Reduced compression on the gaskets and increased draughts.

Misalignment between window and frame beads.

Espagnolette locking mushrooms or cams missing their keeps.

Conversely, fitting a lower stack height where a higher one is needed can cause the sash to crash into the frame before the handle is fully closed, potentially damaging the locking system or glass.

How to identify existing stack height

There are a few practical ways to determine the stack height on an existing window hinge:

Method 1: Visual inspection and manufacturer marking

Some hinges are stamped with their stack height (e.g. “13” or “17”) along the track or arm, often alongside the manufacturer’s brand (Yale, ERA, Mila, etc.) and length marking. Check both hinges carefully; the marking can be near the pivot or at the end of the track.

Method 2: Direct measurement

If there is no marking, you can measure the stack height directly with a vernier caliper or a ruler:

Open the window fully so the hinge is accessible.

Locate the frame leaf (the part screwed to the fixed frame).

Measure the height from the frame fixing surface to the centre of the hinge pivot where the sash sits; this is your approximate stack height.

In practice, most homeowners and many trades simply compare the thickness visually with a known 13 mm or 17 mm hinge from our friction hinges range.

System-specific stack heights

Certain window profile systems have preferred stack heights. For example:

Many older uPVC systems – Typically 13 mm stack hinges.

Some modern slimline uPVC and aluminium systems – Often use 13 mm to keep sightlines tight.

Deeper, more insulated or timber systems – May use 17 mm to accommodate larger gasket sets.

When supplying the trade, it is common practice to ask for the window system or fabricator (e.g. Liniar, Rehau, Eurocell) so we can advise the most likely stack height. For DIY customers, providing clear photos and some basic measurements can help us match the correct product in our window hinges category.

Adjustable or packer-based solutions

In some situations, especially on timber or aluminium frames, it is possible to fine-tune the effective stack height by using hinge packers or shims. A few tips from site experience:

Use purpose-made plastic packers rather than improvised materials, to avoid long-term compression or decay.

Ensure packers run the full length of the hinge where possible, to maintain support.

Always maintain consistent stack on both top and bottom hinges to avoid twisting the sash.

However, packing should not be used to try to compensate for a completely incorrect stack height choice; significant differences are best resolved by selecting the correct hinge model.

3. Fire escape requirements

Overview of UK fire escape rules for windows

In the UK, escape windows are covered primarily by Approved Document B (Fire Safety) to the Building Regulations. While this guide is not a substitute for the regulations themselves, it is useful for both trades and homeowners to understand the key requirements that influence hinge choice.

For many houses and low-rise flats, certain windows must be capable of providing a secondary escape route in the event of a fire. These are usually in:

Habitable rooms (such as bedrooms, living rooms and studies) on upper floors.

Rooms that rely on the window as their designated means of escape, where escape routes through the building may be compromised.

Minimum clear opening sizes

For a window to qualify as an escape window, it must provide a sufficient clear opening, not just a large glass area. The requirements typically include:

A minimum clear opening area of 0.33 m² (0.33 square metres).

A minimum clear opening height of 450 mm.

A minimum clear opening width of 450 mm.

The measurements are taken across the actual opening where a person could pass, not the overall sash size. This is where egress hinges are essential, as they move the sash away from the frame to achieve maximum opening width.

Height above floor level

The bottom of the clear opening should generally be:

No more than 1100 mm above the finished floor level.

This is to ensure occupants, including children, can reasonably climb up to the window and then out onto a roof, balcony or other safe surface used for escape.

Why egress hinges are required

Standard friction hinges on side-hung windows can sometimes meet the minimum opening sizes, but in practice the following often limit the usable escape opening:

Deep frame and sash profiles, reducing the clear space.

Internal plaster reveals or tiles projecting into the opening.

External cladding or brickwork returns reducing the effective width.

Egress hinges are designed to:

Open the sash to approximately 90 degrees from the frame.

Move the hinge-side of the sash away from the frame by “knuckling” the hinge.

Maximise the clear space between the sash and frame on the hinge side.

This significantly increases the measured escape opening without needing to enlarge the overall window size.

Combining fire escape with safety restrictions

On upper floors, there is often a tension between child safety (limiting the day-to-day opening) and escape requirements (allowing a full opening in an emergency). The usual solution is:

Use egress easy-clean friction hinges.

Add a restrictor device that automatically limits the initial opening to around 100 mm.

Ensure the restrictor can be intentionally released by an adult, often with a key or simple push/slide mechanism, to allow full escape opening.

It is important that any restrictor used on an escape window does not permanently prevent the window from opening to the required size. Products used should comply with relevant standards (e.g. BS EN 14351 for performance of windows and doors) and be installed according to the manufacturer’s instructions.

Location and suitability of escape windows

While hinge choice is important, not every window can or should be used as an escape window. General guidance from Approved Document B includes:

Escape windows should lead to a place of safety, such as a flat roof that is strong enough to support people, or directly to ground level.

Windows opening onto lightwells or enclosed spaces may not be suitable unless there is a safe route from those spaces.

Top-hung windows are rarely effective as escape windows due to restricted access at the bottom edge.

As a rule of thumb, if you are replacing windows in a bedroom on an upper floor and the existing windows are used (or required) as an escape route, you should normally fit side-hung sashes with appropriate egress hinges.

Relevant standards and guidance

When specifying or selecting hinges from our friction hinges range for escape windows, consider:

Approved Document B (Fire Safety) – Requirements for escape windows, including dimensions.

BS 8213-1 and BS 8213-4 – Guidance on design, selection and installation of windows, including safe cleaning and access.

Manufacturer datasheets – Egress hinges from brands like Yale, ERA, Avocet and Mila will state whether they are suitable for escape applications and the clear opening dimensions they can achieve with typical frame profiles.

For trade customers, keeping datasheets and installation guides on file is a sensible way to demonstrate due diligence and compliance with regulations.

4. Measuring guide

General approach to measuring window hinges

Whether you are a window installer, maintenance contractor or DIY homeowner, correct measuring is the key to a successful hinge replacement. The four main measurements you will need are:

Hinge length.

Stack height.

Hinge width (especially on side-hung windows).

Fixing hole positions (for certain specialised systems).

Measuring is usually done with the old hinge removed from the window. If that is not possible, take as many measurements as you can with the hinge in situ and provide clear photos for technical support.

Step-by-step: Measuring hinge length

Hinge length is normally the simplest measurement:

Open the window and support the sash.

Unscrew and remove one hinge entirely from the window.

Lay the hinge flat on a table or workbench.

Measure from the very end of the track to the opposite end – this is the overall hinge length, in millimetres.

Convert to inches where helpful (e.g. 200 mm ≈ 8", 250 mm ≈ 10", 300 mm ≈ 12", 400 mm ≈ 16", 600 mm ≈ 24"). Most products in our window hinges range are listed in millimetres, but also commonly known by their inch sizes.

Step-by-step: Measuring stack height

As covered earlier, stack height is the vertical offset. If the hinge is removed:

Place the hinge flat on its frame leaf (the side that would be against the window frame).

Use a vernier caliper or ruler to measure from the base surface to the underside of the sash arm where the sash would sit.

Record this measurement in millimetres – typically 13 mm or 17 mm.

If measuring in situ:

Open the window fully.

Measure from the outer frame surface to the underside of the sash where it meets the hinge.

Subtract any packers or visible spacers to approximate the hinge stack.

Determining hinge handing (left/right)

Unlike many door hinges, most friction hinges are handed by their installation position on the window. To identify handing:

Stand inside the room, facing the window.

If the hinges are on your left and the window handle is on your right, that is a left-hand window (and vice versa).

However, many friction hinges are actually “universal handed” – a single hinge pattern can be fitted either side. Egress hinges and some specialist designs may be supplied as distinct left-hand and right-hand versions. The product descriptions in our friction hinges section indicate if a hinge is handed or universal.

Measuring hinge width and sash weight

The width or depth of the sash and frame can affect which hinge series is suitable, especially for heavy triple-glazed units or tall aluminium sashes. Consider:

Sash height and width – Measure the visible sash size (in mm) and note whether it is top-hung or side-hung.

Estimated sash weight – As a rough guide, a standard 28 mm double glazed unit weighs around 20–22 kg per m² of glass area. Add an allowance for the sash profile (typically 5–10 kg).

Hinges from manufacturers like Securistyle, Nico and Yale often specify maximum sash weights and sizes. For example, a 300 mm side-hung hinge may be rated up to 22 kg, while a 400 mm heavy duty hinge may be rated to 35–40 kg or more. Always check load ratings when dealing with large or heavy sashes.

Measuring for egress hinges

When upgrading to egress hinges to meet fire regulations, it is important to verify that the existing frame and sash sizes will achieve the required escape opening. As a basic method:

Measure the clear frame opening width (from inner reveal to reveal).

Measure the sash width and calculate the opening that will remain when the sash is fully open.

Check the manufacturer’s datasheet for the egress hinge to confirm the expected clear opening with that frame profile.

In many cases, if a window was originally installed as an escape window, replacing like-for-like with modern egress hinges of similar size will maintain compliance. If in doubt, consult a qualified installer or surveyor.

Fixing hole positions

Most modern friction hinges have industry-standard fixing hole centres that are compatible across brands. This makes replacement much easier for both trade and DIY users. However, on older or proprietary systems, fixing holes may not line up exactly.

When this occurs, you can:

Mark new fixing positions on the frame and sash, making sure there is still adequate edge cover and screw pull-out resistance.

Use appropriate screw types and lengths for the substrate (uPVC reinforcement, aluminium or timber).

Seal redundant holes in timber frames to prevent water ingress.

If you are working on commercial aluminium systems or older timber windows, it can be helpful to send photos and measurements to our technical team so we can suggest the nearest suitable product from our window hinges selection.

DIY tips for removing and replacing friction hinges

Tools you will typically need

Pozidriv or Phillips screwdriver (or suitable bit for your drill/driver).

Small adjustable spanner or hex key for friction adjustment (depending on hinge type).

Measuring tape and pencil.

Timber wedge or helper to support the sash.

Removal procedure

Open the window fully.

Support the sash from underneath with a wedge or have a second person hold it.

Unscrew the screws fixing the hinge arms to the sash first.

Then unscrew the hinge track from the frame.

Carefully remove the sash from the opening.

Take care with large or heavy windows. For many side-hung sashes above 800 mm high, having a second person assist is strongly recommended.

Fitting new hinges

Offer up the new hinge to the sash and align with the existing holes where possible.

Secure the sash arms first, using the correct screw type and length.

Fit the track to the frame next, checking the sash is centrally aligned in the opening.

Close and open the window slowly, confirming that the sash seals correctly all round without binding.

Adjust friction screws as necessary so the window will stay open at typical positions.

After fitting egress or easy-clean hinges, show the homeowner or user how to operate the escape and easy-clean functions safely.

5. Common faults

Overview of typical friction hinge problems

Friction hinges work hard throughout their life, often in harsh weather conditions. Over time, wear, dirt, corrosion and general movement of the building can all cause issues. Recognising symptoms early allows simple repairs before more serious damage occurs.

Fault: Window difficult to open or close

Symptoms:

Handle is stiff to operate.

Sash feels “stuck” or jerky when opening.

The window needs to be slammed to close properly.

Likely causes

Friction screws overtightened, causing excessive resistance.

Dirt, paint or debris in the hinge track or on friction pads.

Minor frame movement putting the hinge out of alignment.

Worn friction pads causing the metal to bind.

Solutions

Back off the friction screw by a quarter turn at a time on each hinge, testing the operation as you go. Do not over-loosen or the sash may not hold in position when open.

Clean the hinge tracks and moving parts with a soft brush and mild detergent; rinse and dry thoroughly.

Apply a light lubricant (such as a silicone spray or light engineering oil) to pivot points, but avoid contaminating the friction pads themselves.

If the hinge is severely worn or corroded, replacement with a quality stainless steel hinge from our friction hinges range is often the best long-term fix.

Fault: Sash dropping or misaligned gaps

Symptoms:

Larger gap on one side or at one corner when the window is closed.

The sash appears to have “dropped” on the handle side.

Drafts or water ingress at one corner.

Likely causes

Wear in the hinge pivot rivets, especially on older or heavily used windows.

Incorrect hinge length or stack height fitted during a previous repair.

Loose fixing screws or stripped screw holes in the sash or frame.

Sash too heavy for the hinge rating, leading to long-term distortion.

Solutions

Check all screws are tight and that the hinge is firmly attached to both frame and sash.

If screw holes are stripped in timber, plug and re-drill them. In uPVC, consider using slightly larger or longer screws into the reinforcement.

If the hinge shows visible play at the pivots, replace with new hinges of the same length and stack height.

For very heavy sashes, upgrade to heavy-duty hinges from recognised brands like Yale, ERA, Mila or Nico, ensuring they are correctly rated for the sash weight.

Fault: Draughts or water leaks around sash

Symptoms:

Cold air felt around edges when the window is closed.

Water staining or leaks under heavy rain and wind.

Visible daylight between sash and frame.

Likely causes

Incorrect stack height, preventing proper compression on the window seals.

Worn or perished window gaskets.

Twisted or warped sash, sometimes due to unequal hinge wear.

Hinge misaligned or incorrectly fitted, causing the sash to sit skewed.

Solutions

Confirm the fitted hinge stack height matches the original or the specification for the window system (13 mm or 17 mm most commonly).

Inspect and replace worn gaskets as necessary.

Check that both hinges are of the same type, length and stack height; mismatched hinges can twist the sash.

Adjust fixings or hinge position slightly to square up the sash, being careful not to compromise screw pull-out strength.

Fault: Window will not stay open (slams shut or blows open)

Symptoms:

Window slams shut in light winds.

Sash swings fully open with very little resistance.

Difficult to leave the sash at a comfortable mid-open position.

Likely causes

Friction screws too loose or missing.

Worn friction pads or damaged hinge arms.

Window significantly heavier than the hinge was designed for.

Solutions

Locate the friction adjustment screw on each hinge and tighten gradually until the sash will hold in an open position.

If the friction pads are worn smooth or the arms are bent, replace the hinges; attempting to bend hinges back into shape is not recommended and can be unsafe.

On particularly heavy triple-glazed or large sashes, upgrade to heavy-duty or high-performance hinges from established brands listed in our window hinges category.

Fault: Egress function not working correctly

Symptoms:

Window does not open wide enough for escape.

Sash does not move away from the frame when fully opened.

Easy-clean slide function jammed or extremely stiff.

Likely causes

Incorrect hinge type fitted – standard hinge instead of egress or easy-clean.

Hinge fitted the wrong way round (e.g. left-hand hinge used on right-hand side).

Paint, sealant or debris obstructing the knuckle or slide mechanism.

Long-term wear or abuse damaging the egress linkage.

Solutions

Visually inspect the hinge and compare to product images and datasheets from our egress friction hinges range to confirm you have the correct type.

Ensure hinges are fitted as per manufacturer instructions, with correct handing and orientation.

Clean away any paint or debris carefully; avoid using excessive force that could bend components.

If the egress or easy-clean mechanism is damaged, replace the hinge pair rather than trying to repair individual parts.

After any work on an escape window, always check that the minimum required clear opening is still achieved and that occupants understand how to use the egress function.

Fault: Corrosion and rust

Symptoms:

Visible rust marks or staining on the hinge arms or track.

Rough operation and grinding noises when opening.

Loose or failing pivot rivets.

Likely causes

Low-grade or uncoated steel hinges used, especially on older installations.

Coastal or industrial environments accelerating corrosion.

Lack of maintenance and lubrication over many years.

Solutions

Replace with stainless steel hinges with an appropriate corrosion resistance rating (e.g. Grade 4 to BS EN 1670) from reputable manufacturers like Avocet, Securistyle, Nico or ERA.

On coastal properties, consider upgraded marine-grade or enhanced finish products.

Introduce an annual maintenance routine: clean hinges, check for corrosion, lightly lubricate moving parts, and adjust friction as needed.

Fault: Noisy operation (creaking, grinding)

Symptoms:

Loud squeaking or grinding when the window is opened or closed.

Clicking or knocking noises from the hinge area.

Likely causes

Lack of lubrication on pivot points.

Dust and debris in the hinge track.

Early stages of wear or corrosion.

Solutions

Clean the hinge track with a soft brush and vacuum, removing any obvious debris.

Apply a small amount of silicone spray or light oil to pivot rivets and metal-on-metal joints (avoid soaking the friction pads).

If noise persists and play is evident at the pivots, plan for hinge replacement.

Trade versus DIY: When to call a professional

Many hinge-related issues are straightforward for competent DIYers to address, particularly on ground-floor windows. However, given the safety implications of escape windows and working at height, there are situations where engaging a professional installer or maintenance engineer is sensible:

Windows on upper floors where external access is limited or unsafe.

Very large or heavy sashes that are difficult to handle safely.

Properties covered by specific regulations or warranties (e.g. new-builds, social housing, commercial buildings).

Any situation where you are unsure about compliance with Building Regulations, especially regarding fire escape windows.

Trade customers can source bulk quantities and specific systems hardware through our window hinges range, while DIY customers can rely on detailed product descriptions, photos and technical advice to select the right replacement parts.

Preventive maintenance advice

To extend the life of your hinges and keep windows operating smoothly:

Inspect windows annually for signs of wear, corrosion or misalignment.

Clean hinges, frames and drainage channels to prevent water build-up and debris.

Lightly lubricate hinge pivots and locking mechanisms once or twice a year.

Check and adjust friction settings if windows no longer hold their position or are too stiff.

For rented or managed properties, keep a simple log of inspections and maintenance for compliance and safety records.

With the right choice of hinges from high-quality brands and a small amount of periodic maintenance, modern friction and egress hinges can provide decades of reliable service on UK uPVC, aluminium and timber windows.