Bifold Door Security and What Locks to Look For

Bifold doors have several moving parts and a large amount of glass, so their security depends on the locking mechanism, the hardware and how well they are fitted rather than how they look. Suppliers describe a multi-point locking system as standard and the lock and handle as the heart of the door's security. Knowing what standards to ask for will help you choose a secure set of doors or check the ones you already own.

Why people worry about bifold door security

Bifold doors are a common feature of modern kitchen extensions, designed to open up the back of a house to the garden. Many buyers and homeowners worry that a wall of glass and multiple folding joints must be easy to break through. When closed, the hinges often rest on the exterior, which suppliers note is a vulnerable area if the hardware is weak or poorly designed. Because there are several moving parts and a large expanse of glazing, the strength of the door depends on the locks, the frame materials and the type of glass used.

The MLA says a single euro cylinder means fewer locks to defeat, so it must be tested to SS312 Diamond or TS 007 3 star. That makes the standard of the cylinder crucial to your home security. The choice of locking points and hardware is therefore a major concern for anyone investing in these doors.

How bifold doors lock

Most bifold doors feature a multi-point locking system as standard to secure the doors at different areas around the frame and track. This means that when you operate the main handle, a central gearbox drives a series of metal hooks and bolts into keeps situated along the door frame. The exact number of locking points depends on the height and design of the doors, but the principle is the same as a modern front door.

The main lock is operated by a euro cylinder, which is the barrel where you insert your key. To engage the multi-point locking mechanism, you must lift the handle, turn the key and then remove the key completely. If you only pull the door shut without lifting the handle and turning the key, the hooks will not engage. The door is not fully locked in this state. The Master Locksmiths Association advises that if your locking system does not lock properly, your insurance may not cover you for your losses.

On a set of folding sliding doors, there is usually one main traffic door that opens like a normal back door for everyday use. The number and type of locking points for the other folding sections depend on the design, so ask the supplier how each section is secured.

What PAS 24 and Secured by Design tell you

When you research new folding doors, suppliers will often mention PAS 24 and Secured by Design. PAS 24:2022 is the current British Standard that specifies test methods and acceptance criteria for the enhanced security performance of doorsets and windows. The British Standards Institution states that it tests products intended to resist attacks normally associated with the casual or opportunistic burglar. It is a benchmark to show that a door can withstand typical, unsophisticated attempts to break in.

The standard covers many door types, including folding sliding doors on single and multi-track systems. However, PAS 24 applies to new doorsets as manufactured and prior to installation. It does not test component performance on its own, nor does it test installation requirements. This means a door is only as strong as the way it is fitted to your home. If a highly rated door is installed poorly, the PAS 24 certificate will not stop a burglar from forcing it open.

Secured by Design is the police backed scheme. Certification to PAS 24 is one way for a doorset or window to meet the Secured by Design scheme. The Police Crime Prevention Handbook recommends that if you are replacing your door, you should always use a security accredited product to a standard such as PAS 24:2022. PAS 24 is also referenced in Approved Document Q of the Building Regulations for England and Wales, which sets out security standards for new housing. You can read more about pas 24 and secured by design doors to understand what these certificates cover.

Cylinder and handle standards

Euro cylinders can be vulnerable to lock snapping. Because bifold doors often rely on a single cylinder, it must be tested to the highest standards. The Master Locksmiths Association recommends specific lock standards for retro fit upgrades to ensure the cylinder cannot be easily defeated.

For a cylinder change only solution, they recommend a Sold Secure SS312 Diamond cylinder. If you are changing both the cylinder and the handle, you can use a TS 007 one-star cylinder combined with a two-star rated handle, or a TS 007 three-star cylinder. Either TS 007 solution must achieve a total of three stars to be effective against attack.

You can check what you have by looking at the face of the cylinder where the key goes in. A three-star cylinder will normally have three stars stamped into the metal, while a Sold Secure Diamond cylinder will display a diamond logo. If your cylinder has no marks, it may not meet these standards, so ask a locksmith to check it. You can learn more in the guide to anti snap locks explained.

Here is a summary of the Master Locksmiths Association minimum security recommendations for upgrading a euro cylinder.

These are the MLA recommendations for retro fit upgrades in Edition 19 (January 2025) of its domestic guidelines.

Glass and frames

A strong lock and a three-star cylinder are worth less if the glass around them can be easily smashed. Glazing is a major part of any bifold door and it needs to be tough enough to resist a physical attack. The Police Crime Prevention Handbook advises that glazing can be reinforced with special film or laminated glass panels to improve security.

Laminated glass features a tough plastic layer sandwiched between two panes of glass. If the glass breaks, the plastic layer holds the shattered pieces together within the frame. It acts as a physical barrier even after the glass has failed.

Toughened glass is a different product and breaks into small pieces rather than holding together. When ordering doors, ask your supplier whether laminated glass will be used, particularly on the main traffic door near the lock.

Questions to ask the supplier before you order

Getting the right answers from your supplier helps you check what you are buying, though insurers differ in what they ask for. Because PAS 24 covers the door as it leaves the factory, you also need to know who is responsible for fitting it correctly. Suppliers will often state that bifold door security relies heavily upon a secure, resilient locking system, so you must press them on the details.

Ask the supplier these questions before you agree to a purchase or pay a deposit:

• Can you provide the PAS 24 certificate and confirm the version year is current?
• How many locking points does the multi-point locking mechanism have?
• Does the supplied euro cylinder and handle combination achieve a total of three stars?
• Is the glass laminated or toughened on the main traffic door?
• Who exactly will fit the doors and who guarantees the installation?

Make sure you get the PAS 24 certificate for the exact door configuration you are buying. A certificate is only useful if it matches the exact door configuration being installed in your home.

Checking and upgrading bifolds you already have

If you have moved into a house with bifold doors, you should check how secure they are before assuming they will keep burglars out. Start by looking at the euro cylinder on the outside. The police advise that if you have a europrofile lock, you should inspect it from the outside and if it protrudes beyond the frame handle, consider getting an MLA member to change it to a shorter lock more resistant to snapping.

You can upgrade the security of existing bifold doors without replacing the whole frame. A locksmith can change the euro cylinder to an SS312 Diamond or a TS 007 three-star model. If the handles are worn or flimsy, they can be swapped for two-star security handles that protect the cylinder underneath. This is a fast and effective way to meet police recommendations for replacement components.

Always double lock multi-point locking doors by lifting the handle, turning and removing the key. If a bolt does not seem to engage fully or the door is hard to lock, ask the door supplier or a locksmith to look at it.

Insurance and your policy wording

Insurers differ in what they ask for, so you must check your own policy wording carefully to see what applies to patio or folding doors.

The Master Locksmiths Association states that locks for uPVC and composite multi-point doors should meet PAS 3621, PAS 8621 and PAS 10621. Furthermore, locks that have been part of a PAS 24 door test are also acceptable. The MLA also says locks that have been part of a PAS 24 door test are acceptable.

The Master Locksmiths Association advises that written agreement for the acceptance of such locks should be obtained from the insurer by the policyholder. Do not guess what your insurer will accept. Send them the PAS 24 certificate or the lock rating and get their approval in writing.

What a locksmith can and cannot do

A professional locksmith can repair and upgrade the locking mechanism on bifold doors. If your door is jammed shut, the handle spins freely or the key will not turn, they can gain non-destructive entry and replace the faulty parts. They can swap the central gearbox or the euro cylinder without needing to replace the entire multi-point locking strip, which keeps the cost down.

There is no government licensing of locksmiths in the UK, meaning anyone can trade as one. The Master Locksmiths Association is the main trade association and runs a voluntary approval scheme. Its approved companies are vetted, have criminal record checks, employ locksmiths who have passed the MLA exam and are inspected regularly. Using an approved company is a good way to ensure the person working on your doors knows how to fit high security cylinders correctly.

Watch out for common warning signs of a bad locksmith before you let them work on your doors:

• National call centres advertising as a local locksmith but passing the job to whoever is nearest.
• A very low price quoted on the phone that multiplies once they arrive on the doorstep.
• Drilling a lock that could have been opened without damage.
• Replacing a whole multi-point mechanism when only the cylinder or gearbox had failed.
• Refusing to give a total price before starting work or asking for cash only with no invoice.

Under the Consumer Rights Act 2015, a locksmith service must be carried out with reasonable care and skill, at a reasonable price if none was agreed, and within a reasonable time. You have a right to have poor work put right or your money back. Under the Consumer Contracts Regulations 2013, there is normally a 14-day cancellation period for work arranged at home or by phone. This does not apply where you specifically asked for a visit for urgent repairs, although any extra work sold during that visit is not covered by this exception.

A locksmith cannot usually realign doors that have dropped due to heavy glass or poor installation, as this is a job for a double glazing repair specialist. They also cannot certify an existing door to PAS 24, because that standard only applies to new doorsets before they are installed.

Common questions

Can you fit extra locks to bifold doors?

Check with the door supplier before any extra locks are fitted, because changes to the frame may affect the guarantee. Upgrading the main cylinder to a three-star standard and ensuring the glass is secure are better ways to improve security.

Are bifold doors easy to break into?

Doors that hold a PAS 24 certificate and feature a three-star cylinder and laminated glass are designed to resist a casual or opportunistic burglar. Their security relies heavily on you lifting the handle and turning the key every time you close them.

What happens if the bifold door lock breaks?

If the handle spins freely or the door will not lock, the central gearbox has likely failed. A locksmith can normally open the door using non-destructive entry and replace just the gearbox rather than the whole locking strip. You do not usually need to replace the doors themselves just because a lock component has broken.

Do I need a specific type of key for bifold doors?

Bifold doors normally use a euro cylinder, so the key depends on the cylinder fitted. Ask a locksmith whether the cylinders can be keyed alike with your front door, meaning one key opens both.

Next steps before you hire a professional

Whether you are buying new doors or upgrading your current locks, follow these steps to make sure your home is secure:

• Check your home insurance policy to see exactly what standard of locks your insurer expects on patio or folding doors.
• If ordering new doors, ask the supplier for the PAS 24 certificate for the exact doorset you are buying.
• Look at your existing euro cylinder from the outside to see if it protrudes beyond the handle or shows any star ratings.
• Ask a locksmith for a total price including parts, VAT and any call-out charge before they start work.
• Check that the locksmith has a real local address and ask to see their ID when they arrive.

Getting the locks right on a large set of folding doors brings peace of mind and gives you something clear to show your insurer. If you need a cylinder upgraded or a broken gearbox replaced, take the time to find a locksmith near you who can fit the right standard of hardware.