How Secure Are Aluminium Bi-Fold Doors?
12 August 2026The short answer: a modern aluminium bi-fold door is not a weak point. Security comes from three things working together: the strength of the frame, the locking engaged along it, and the glass. Aluminium is the strongest of the common frame materials, and a properly specified bi-fold locks at multiple points on every panel rather than at a single latch.
It is a fair question to ask. You are replacing a solid wall with glass, so it feels like you are trading security for light. Here is what actually determines whether that is true.
Does a big glass door make my house easier to break into?
Not by itself. Most break-ins are opportunistic and go for whatever is quickest: an unlocked door, an old window with a worn catch, a single-point lock that can be levered. A large modern door with multi-point locking and toughened or laminated glass is a slower, noisier target than a tired back door, regardless of how much glass it contains.
What matters is the specification, not the size. A cheap door of any size is a weak point. A well-specified one is not.
What actually keeps a bi-fold door secure?
The frame
Aluminium is a structural metal. It does not flex under load the way a plastic section can, and it does not need an internal reinforcement to achieve its strength because the strength is the material. That matters because many forced entries work by flexing or levering a frame until a lock disengages, rather than by breaking glass.
The locking
This is the part to ask about on your quotation. A bi-fold should engage at multiple points along its height rather than at one latch, and each panel should be secured to the ones either side of it, not just the traffic door to the frame. Ask specifically what locking is fitted, how many engagement points there are, and how the intermediate panels are secured.
The glass
Glass specification is a genuine choice and worth making deliberately. Toughened glass breaks into blunt granules rather than shards, which is a safety benefit. Laminated glass holds together when broken because of the interlayer bonding it, which is the security benefit, since an opening cannot easily be made through it. If security is your main concern, laminated is the specification to discuss.
The hinges
Bi-folds carry their weight on hinges and rollers, so those are load-bearing as well as security components. Hinge bolts and the way the panels are retained on the track are worth asking about, particularly on wide sets where the panels are heavy.
What should I ask on the quotation?
Rather than accepting a general reassurance, ask for the specifics in writing:
- What locking system is fitted, and how many locking points per panel?
- How are the intermediate panels secured to each other?
- What glass specification is included, and is laminated available?
- What cylinder is fitted to the traffic door, and to what standard?
- Is the hardware covered by the guarantee, and for how long?
Any competent installer will answer all five without hesitating. We set the answers out on your quotation so you can compare them properly against other prices, rather than comparing two numbers and hoping the specifications match.
Is a sliding door more secure than a bi-fold?
Neither format is inherently more secure. A sliding door has fewer opening joints simply because it has fewer panels, while a bi-fold has locking engaged at each panel. Both come down to the hardware specified and how well the door is installed. If you are choosing between the two, do it on how they open and how they look, and specify the security you want on whichever you pick.
Does installation affect security?
Considerably, and it is the part most people never think about. A door is only as secure as its fixing into the structure. Correct packing, the right fixings into sound material, a properly supported head above the opening, and a threshold that is bedded and sealed correctly all matter. A well-made door fitted badly is not a secure door.
This is the main argument for using an installer who fits the system regularly rather than the cheapest quote, and it is why we train directly on the systems we install.
Common questions
Are aluminium bi-fold doors more secure than uPVC?
The aluminium frame is stronger and stiffer, which helps against levering attacks. But the locking and glass matter at least as much as the frame material, so a well-specified uPVC door can be more secure than a poorly specified aluminium one. Compare specifications rather than materials.
Should I choose laminated or toughened glass?
Toughened is the usual safety glazing and breaks safely. Laminated holds together when broken because of its interlayer, which makes it the better choice where security is the priority. Discuss it before the order rather than after.
Can bi-fold doors be locked when partly open?
The traffic door is designed to be used and locked on its own like a normal door, which is how most people use a bi-fold day to day. Configurations vary by system, so confirm the arrangement for the set you are quoted.
Do you fit locks to a standard?
Hardware standards vary by system and by what is specified, so we set out exactly what is included on your quotation rather than making a blanket claim here. If a particular standard matters to you, tell us before we quote and we will confirm what is available.
Talk to us about specification
If security is the thing making you hesitate about a large glazed opening, say so when we survey. It changes what we recommend on glass and hardware, and it costs less to specify correctly at the start than to change afterwards. Get in touch or call 01293 226523.
More on the range: aluminium bi-fold doors, sliding and patio doors and handles and accessories.