A keyed lock on an aluminium sliding door is a system rather than a single item. A lock body sits inside the stile and throws a hook into a keeper on the jamb, a replaceable cylinder provides the key interface, and auxiliary bolts cover the attacks the main lock cannot. Understanding which part does what makes it far easier to decide what you need, what to upgrade, and what to do when keys go missing.
Keyed and non keyed sliding doors
Not every aluminium sliding door has a key.
Older residential sliders and many internal or low risk doors are fitted with a snib or latch only. A small catch holds the panel closed and is released by hand from either side. It stops the door drifting open and provides essentially no security.
A keyed lock requires a key to release from outside, and depending on configuration may require one from inside as well. This is the standard specification on any external sliding door today.
If you have an older door with a snib only, upgrading is usually possible without replacing the door. The stile is a hollow section, so a keyed mortise lock can often be fitted where a snib currently sits. Whether it is straightforward depends on the suite and the section, which is the first thing worth establishing.
The parts of a keyed sliding door lock
Four components make up the system, and they are bought, fitted and replaced separately.
The lock body sits inside the lock stile and contains the mechanism. On sliding doors it throws a hook or claw bolt rather than a straight deadbolt, because a hook engages behind the keeper and tightens when the panel is levered away rather than releasing. We cover the mechanism in our article on mortise locks for aluminium sliding doors.
The cylinder is the keyed barrel that drives the lock body. It is a separate, replaceable part, which means rekeying or upgrading security is usually a small job. See our article on cylinder locks for aluminium sliding doors.
The keeper is fitted to the jamb and receives the bolt. It is not part of the lock but it determines whether the lock works, and misalignment between bolt and keeper is the most common cause of a lock that has become stiff.
Auxiliary bolts are separate devices covering attacks the main lock does not. The most important is anti lift, since no mortise lock prevents the panel being lifted clear of its sill track.
Choosing a locking configuration
Four decisions cover most situations.
Single point or multi point. A single point lock engages the jamb at handle height only, leaving the top and bottom of the panel held by nothing but the tracks. On a tall panel that invites levering. A multi point system engages at several heights from one handle movement, and it also compresses the jamb seal along the full stile, which reduces draught and noise. On panels above roughly two metres it is worth the difference. See our article on multi point locks for aluminium sliding doors.
Keyed both sides or thumb turn. A thumb turn opens from inside without a key, which matters because sliding doors are frequently escape routes. Keyed both sides defeats a reach through attack but creates a serious hazard in a fire. The better answer to reach through is usually laminated glass rather than a second keyway, and we set out the reasoning in our article on thumb turn locks for aluminium sliding doors.
Auxiliary bolts. At minimum, a bolt engaging the head track, because lifting the panel out of its track is how these doors are most commonly defeated and the main lock does nothing to prevent it. See our article on patio bolts for aluminium sliding doors.
Cylinder security. Anti snap, anti drill and anti pick features cost modestly more and address every common attack on the cylinder itself. Ensuring the cylinder sits flush rather than protruding costs nothing and matters just as much.
Key control, which matters more than most people expect
Mechanical strength is only half of what a keyed lock provides. The other half is knowing who can open the door, and that half is easier to lose.
When you move into a property, you have no way of knowing how many keys exist or who holds them. Previous owners, tradespeople, cleaners, agents and former tenants may all have copies. Rekeying the cylinders is inexpensive relative to the uncertainty, and because cylinders are separate replaceable parts it is a small job.
Restricted key systems use a patented keyway, so blanks are not sold at hardware shops or key cutting kiosks. Copies can only be cut by an authorised locksmith against documented authority, and a record is kept. This is the single most effective way to regain control of who can enter, and it is under used in Australian residential work.
Keyed alike means several doors operate from one key. Practical in a house with a front door, a back sliding door and a garage side door, and it removes the temptation to leave a rarely used door unlocked because its key is inconvenient. A lock that gets used because the key is to hand is worth more than a stronger one that does not.
Master keying allows each door its own key while a master operates all of them. Standard in commercial premises and strata buildings.
Keyed alike and master key arrangements are easiest to organise when the doors are ordered, since matching cylinders across mismatched profiles afterwards is not always possible.
Rentals, strata and key obligations
Key control moves from good practice to obligation in tenanted and strata properties, and the detail is worth confirming rather than assuming.
Residential tenancies in New South Wales place obligations on landlords to provide and maintain locks or other devices necessary to keep the premises reasonably secure. There are also rules about altering locks during a tenancy and about providing keys to tenants. The specifics matter and change, so confirm the current position with NSW Fair Trading or a property professional rather than relying on a general description.
Strata schemes frequently operate master key or restricted key systems across common property, and individual lot owners changing a lock in a way that breaks that system creates problems for building management and emergency access. Check with the owners corporation before changing cylinders on any door that forms part of a building wide system.
Between tenancies, rekeying is worth treating as routine rather than exceptional. Keys accumulate silently, and the cost of a cylinder change is trivial compared with the alternative.
Insurance
Some home and contents policies contain conditions relating to how the property must be secured, and a few specify deadlocks on external doors or require that the property be locked when unoccupied.
These conditions vary considerably between insurers and policies, and a claim can be affected by whether they were met. It is worth reading the product disclosure statement rather than assuming, particularly if you are upgrading locks anyway.
Where a policy does specify deadlocks, note that a keyed mortise hook bolt on a sliding door generally operates as a deadlock. Confirming this with your insurer before a claim is considerably easier than after one.
Hardware manufacturers used in Australia
Sliding door locks are suite specific, so the hardware generally follows the aluminium system rather than being chosen independently.
Lockwood, part of the ASSA ABLOY group, is among the most widely used lock and cylinder manufacturers in Australia and operates established restricted key systems.
Allegion supplies a range of Australian door and window hardware brands including Whitco, long established in sliding door and window locking.
Doric supplies sliding door hardware matched to the major commercial aluminium suites.
dormakaba supplies architectural hardware and master key systems, more commonly on commercial projects.
Hardware is generally distributed through Lincoln Sentry and Access Hardware, which stock across these brands.
Australian standards
AS 4145 covers locksets and hardware for doors and windows, with AS 4145.2 addressing mechanical locksets and setting performance and security levels.
It applies to the lockset as a product rather than requiring any particular grade on a domestic sliding door, so a homeowner has no obligation to fit a specific level. Commercial and strata projects may carry specification requirements worth confirming.
Note that AS 5039 covers security screen doors and window grilles rather than the locking hardware on the sliding door itself. A sliding door lock cannot be AS 5039 compliant, because the standard does not apply to it. A security screen fitted over the door is what that standard governs.
Standards are revised periodically, so confirm current requirements for your own projects.
Maintenance and coastal conditions
Near the coast, in the eastern suburbs, Northern Beaches and Sutherland Shire, the cylinder is almost always the first component to fail. Salt reaches the keyway directly, since it is an opening in the door face by design, and the small springs and brass pins inside corrode long before a lock body shows wear.
Because the cylinder is a separate part, addressing this early is cheap. Leaving it produces a seized lock body, which usually means removing the panel.
Two maintenance rules cover most of it. Use a dry lubricant, graphite or PTFE based, and never an oil spray, which attracts dust and eventually seizes the pins. And if a key or handle becomes stiff, check whether the door has settled on worn rollers before assuming the lock has failed. A panel sitting low puts the whole mechanism under load.
Putting it together
A well specified external aluminium sliding door in Sydney carries a keyed mortise lock with a hook or claw bolt, a quality cylinder with anti snap and anti drill features sitting flush with the escutcheon, a thumb turn on the inside where the door is an escape route, an auxiliary bolt engaging the head track for anti lift protection, and laminated glazing so that breaking the pane is slow and noisy.
Add a restricted key system where key control is uncertain, and keyed alike across the house so that every door actually gets locked.
Each element addresses a different attack, and no single one substitutes for the others. Our aluminium sliding doors are supplied with matched locking hardware, multi point options and restricted key systems on request.
Frequently asked questions
Can I add a keyed lock to a sliding door that only has a snib?
Often yes. The stile is a hollow section, so a keyed mortise lock can usually be fitted where the snib sits. Whether it is straightforward depends on the suite and the section, so it is worth checking before assuming either way.
How do I know which lock fits my sliding door?
Match the backset, faceplate dimensions, case depth and handing, or identify the door suite and order the lock specified for it. Removing the existing lock and matching it is the reliable approach.
Should I rekey the locks when I move in?
Yes. You have no way of knowing how many keys exist or who holds them, and because cylinders are separate replaceable components it is inexpensive.
What is a restricted key system?
A patented keyway where blanks are not publicly available, so copies can only be cut by an authorised locksmith against documented authority. It is the most effective way to control who can enter a property.
Do my sliding door locks need to meet a standard?
AS 4145 covers locksets as products but does not require a particular security grade on a domestic sliding door. Commercial and strata projects may have specification requirements worth confirming.
Does my insurance require deadlocks?
Some policies contain security conditions and some specify deadlocks, but it varies by insurer. Read your product disclosure statement rather than assuming, particularly if you are upgrading locks anyway.
What is the single most important upgrade?
Anti lift protection at the head track, if you do not already have it. Lifting the panel clear of the sill is the most common way an aluminium sliding door is defeated, and the main lock does nothing to prevent it.
