The right security patio door lock depends on how your door opens. Sliding patio doors need protection against being slid or lifted out of their track, so look at anti-lift blocks, auxiliary patio locks and track bars. French doors need both leaves held firmly and the hinge side protected, so look at a good cylinder, shoot bolts, hinge bolts and handle locks designed for double doors.
This guide goes through the options for each door type, what to check before you buy, and where a replacement door makes more sense than another add-on. We sell door security for single uPVC doors, and our products do not fit patio or French doors, so this is a straight guide to what does.
Why patio and French doors need extra attention
Patio and French doors usually sit at the back of the house, often out of sight of the street, with a lot of glass. City of London Police warns that sliding patio doors are vulnerable to forced entry, and West Yorkshire Police suggests considering additional locks and security for patio and conservatory doors that may be vulnerable.
The weak points differ by door type:
| Door type | Main weak points | What helps most |
|---|---|---|
| Sliding patio door | Panel lifted off its runners; panel forced along the track; basic cylinder | Anti-lift blocks, auxiliary frame-mounted lock, track bar, better cylinder |
| French doors (uPVC) | Cylinder; the second (passive) leaf; handle operation if glass is broken | TS 007 3 star cylinder, secure shoot bolts, handle lock for double doors |
| French doors (timber) | Lock, bolts and hinges on outward-opening doors | BS 3621 mortice sashlock, mortice rack bolts top and bottom, hinge bolts |
Sliding patio door security
1. Anti-lift blocks or devices
Older sliding doors can sometimes be lifted off their runners from outside. Anti-lift devices fit in the top track and fill the gap so the panel cannot be raised. Avon and Somerset Police recommends checking older sliding doors for anti-lift tracks, and West Yorkshire Police notes that a timber batten fixed into the top track can stop a door being lifted out. If you are buying a new sliding door, ask for anti-lift blocks as standard.
2. Auxiliary patio door locks
These are purpose-made locks that fit to the frame or the edge of the door (the stile) and lock the sliding panel to the fixed panel or frame. West Yorkshire Police lists “specifically designed patio door locks fitted onto the frame or stile” as a way to improve security. Most need drilling, so they are better for owners than renters. Look for products carrying the Secured by Design logo, which the same police advice recommends for add-on security products.
3. Sliding door track bars
A track bar is a telescopic rod that sits in the bottom track behind the sliding panel, so the door cannot be slid open. It is cheap, needs no drilling and can be removed in seconds, which makes it useful for renters or as an extra layer at night. It does not stop a lifting attack on its own, so pair it with anti-lift protection.
4. A better cylinder
Many sliding doors use a euro cylinder. If it sticks out beyond the handle, Avon and Somerset Police advise having it replaced with a shorter, break-resistant one. West Yorkshire Police recommends a cylinder rated TS 007 3 star (or a 1 star cylinder with 2 star handles) and says the outside end should not protrude more than 3mm beyond the door furniture.
5. Make sure the sliding panel is on the inside
West Yorkshire Police advises that, when buying a sliding door, you ask for the sliding section to be on the inside. It is worth checking which way round yours is fitted.
French door security
1. Upgrade the cylinder
On uPVC French doors, the cylinder on the main (active) leaf locks the multipoint mechanism. A TS 007 3 star or Sold Secure Diamond cylinder is the single most worthwhile upgrade. TS 007 testing covers snapping, drilling, picking and bumping, as this TS 007 guide explains. Our anti-lock snapping guide covers how to choose one.
2. Check the second leaf
The passive leaf is held by shoot bolts into the head and sill of the frame. Make sure they throw fully and engage firmly. If the passive leaf rattles or the bolts do not engage, get the door adjusted.
3. Handle locks for double uPVC French doors
Devices such as Patlock fit around both internal handles of double uPVC French doors and hold them in the locked position, so the doors stay locked even if the outside handles are operated. Patlock was reported in 2015 as having achieved Secured by Design police recognition, and retailers such as Lockshop Warehouse describe it as designed specifically for double uPVC French doors and not suitable for other door types. Check it suits your handles before buying. Like any internal device, it is fitted from inside, so you need a clear routine for removing it quickly in an emergency.
4. Bolts and hinge protection on timber French doors
For wooden French doors, West Yorkshire Police advises fitting mortice rack bolts to the top and bottom of each leaf, a BS 3621 five-lever mortice sashlock near the middle of the door, and hinge bolts or hinge protectors. If your doors open outwards, the hinge pins are on the outside, which makes hinge bolts or security hinges especially worthwhile.
Glass and the bigger picture
Large glass panels are part of the risk. West Yorkshire Police suggests laminated security glass to BS EN 356 P1A or better for vulnerable doors, and Avon and Somerset Police notes that glazing can be reinforced with special film. Laminated glass is best specified when a door or glazed unit is being replaced.
If your patio or French doors are old, draughty and poorly secured, adding several devices may cost more than it is worth. For replacements, police forces recommend a complete doorset certified to PAS 24, such as PAS 24:2022, and products accredited by Secured by Design. A Master Locksmiths Association member can check your existing locks and hinges. Our article are uPVC doors secure? covers what to look for in a uPVC doorset.
Comparing the options
| Option | Door type | Drilling? | Protects against |
|---|---|---|---|
| Anti-lift blocks | Sliding | Varies by door; ask your installer | Panel being lifted out |
| Auxiliary patio lock | Sliding | Yes | Panel being slid or forced |
| Track bar | Sliding | No | Panel being slid open |
| TS 007 3 star cylinder | Sliding and French | No (replaces existing cylinder) | Attacks on the cylinder |
| Handle lock for double doors | uPVC French | Check the product | Handles being operated |
| Rack bolts and hinge bolts | Timber French | Yes | Leaves forced or lifted at the hinge side |
Practical tips
- Check your door’s warranty before fitting anything that needs drilling; West Yorkshire Police notes that added devices could affect it.
- Keep keys out of sight and out of reach of the door, but somewhere everyone at home knows.
- Do not rely on an internal device alone when you go out: the lock is doing the work then.
- Light the garden side of the house and keep side gates locked, so nobody can work at the door unseen. Our guide on how to secure your home covers the wider picture.
FAQs
What is the best security lock for a sliding patio door?
There is no single best lock. The most effective combination is anti-lift protection, a frame- or stile-mounted auxiliary lock, and a TS 007 3 star cylinder, with a track bar as a no-drill extra layer.
Can I fit a door jammer to patio or French doors?
Handle-bracing door jammers, including the HOLDOOR Door Jammer, are designed for single doors and are not suitable for sliding, patio or French/double doors. Use devices designed for those doors instead.
Are track bars any good?
They are a useful, low-cost extra layer that stops the panel sliding. They do not prevent a lifting attack on their own, so make sure the door also has anti-lift protection.
What should I look for when replacing patio doors?
Ask for a doorset certified to PAS 24, anti-lift protection, the sliding panel on the inside, a TS 007 3 star cylinder and laminated glazing where possible.
Next steps
- Work out what you have: sliding, uPVC French or timber French doors.
- Check the cylinder. If it is not TS 007 3 star or Sold Secure Diamond, replace it first.
- Add the device made for your door type: anti-lift and an auxiliary lock for sliding doors, or a double-door handle lock and good shoot bolts for uPVC French doors.
- Do you also have a single uPVC back or side door? That is where the Door Jammer – HOLDOOR fits. It hooks under the inside handle and braces the door against the floor so it stays shut even if the lock is snapped, bumped or picked. It is Sold Secure Bronze rated and Secured by Design accredited (Police Preferred Specification), needs no drilling, and is made in Britain from British steel. It is used from inside, when someone is home. In a fire: find the key, lift the Door Jammer off, unlock the door and leave the building.
- Not sure what suits your doors? Contact HOLDOOR and we will give you a straight answer, even if it is not one of our products.
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