You lock the patio door and part of you knows that little latch is not doing much. It is a big sheet of glass, facing the back yard where nobody walks past, and that latch is all that holds it shut. You have probably stood there and wondered how hard it would really be to get through it.
How to secure a sliding glass door is really three separate jobs. Stop the panel being slid open. Stop it being lifted out of its track. Stop somebody reaching through the glass for the latch. Most of the hardware sold for this does one of the three, so people buy a bar and still have two other ways in.
The Bureau of Justice Statistics counted 1,609,650 burglary and trespassing victimizations in 2024, about 12 for every 1,000 households. Your patio door is the one with the least holding it shut.
By the end you will know which fix stops what, how to tell which channel your panel runs in, how to take away the room a door needs to be lifted out, what security film really does, and when the door itself is what needs fixing.
I am Gal Cohen, field area manager at JDM Sliding Doors, which is a sliding door repair company working in six states. On those calls I see which of this hardware actually went on properly.
Key takeaways
- Which of the two channels in your door sill the sliding panel runs in decides where a bar or a cut dowel can go. Check that before you buy one.
- A hinged bar that mounts on the door frame at waist height, called a Charlie bar, is the sliding glass door bar you do not have to lift out of the track every time you go outside.
- A pin dropped through a hole drilled where the two panels overlap stops a sliding glass door sliding and stops it lifting. It is the only single fix that does both.
- Worn rollers let the sliding panel settle low in its track. The space that opens up above the panel is what somebody needs to lift it out.
How to secure a sliding glass door, in the order that matters
Short answer: lock it, then stop it sliding, then stop it lifting. Those three steps cover almost every way a sliding glass door gets opened, and the first one is free.
- Lock it every single time. Across 1994 to 2011 the Bureau of Justice Statistics found the largest share of household burglaries were completed unlawful entries. That means somebody got in with no force at all. In 2011 it was 1,618,800 of the 3,394,700 burglaries counted, so close to half.
- Then block the track. A bar or a cut dowel in the channel stops the panel sliding, even when the latch has been broken or picked.
- Then take away the lift room. Screws or plastic blocks in the top track stop the panel being raised and pulled out of the bottom track.
How I know: the entry figures come from two US Department of Justice reports, Household Burglary, 1994-2011 and Criminal Victimization, 2024.
Sliding glass doors are as safe as the hardware somebody put on them. That order is not a ranking of which fix is strongest. It ranks how your door is most likely to be opened, and a door nobody locked beats every piece of hardware below it. So if your latch has stopped catching, why a sliding door stops locking is the job to do first.
| What you do | What it stops | What it still leaves open |
|---|---|---|
| Lock the door every time you come inside | Somebody opening it and walking in | A panel that gets pried or lifted |
| Put a bar or a cut dowel in the track | The panel sliding open at all | Lifting the panel, and the glass |
| Fit a second lock near the bottom or the top | Somebody prying the latch itself open | Lifting the panel, and the glass |
| Put screws or blocks in the top track | Somebody lifting the panel out | Sliding the panel, and the glass |
| Stick security film on the inside of the glass | A quick smash and grab at the latch | Somebody willing to keep hitting it |
| Add a door sensor or a camera | Nothing, it tells you instead | All five of the above |
Check which channel your panel runs in before you buy anything
Crouch down at the bottom of your patio door. Two channels are cut into the sill, one in front of the other. Your sliding panel travels in only one of them, and which one it is changes what you can fit.
On most doors the panel that moves runs in the inside channel, nearest the room. The fixed panel sits in the outside channel. Plenty of doors are built the other way round, which is why this is a look rather than an assumption.
The Seattle Police Department’s home security bulletin puts this check before the shopping: “before deciding on security measures, determine whether your door or window slides are on an inside or outside track.” For a panel on the inside track it suggests a snug wooden or metal dowel in the bottom inside track. For a panel on the outside track it suggests a slide bolt instead.
Block the track, and get the bar the right length
Two things decide whether a bar does anything: how long it is, and which channel you put it in. Cut or set it so it reaches from the closing edge of the moving panel to the jamb, which is the upright piece of frame the door shuts against. Leave almost no slack. Every inch of slack is an inch the panel can be shoved open.
A hardwood dowel or a steel tube in the bottom channel is the cheapest version, and you have to lift it out every time you go outside, so it ends up leaning in a corner. The hinged version fixes that. It mounts to the door frame at waist height and folds down across the opening, and the trade calls it a Charlie bar. The Seattle police bulletin names that one too.
Add a second lock at the bottom or the top
A second lock does not make the first one stronger. It makes somebody work at two places on the door, one low and one high, and no single pry gets both.
- A foot lock, also sold as a foot bolt, screws to the bottom corner of a sliding door panel and drops a steel pin into a hole in the track. You press it with your toe on the way past.
- A slide bolt at the top does the same job at the other end of the panel, into the top track or the head of the frame.
- A pin through the overlap costs the least and holds the best. Seattle’s bulletin gives the method. Find where the moving panel and the fixed panel overlap. If there is enough metal to drill without touching glass, drill a downward-angled hole through the inner frame and halfway into the outer one, then drop in a snug pin. The panel cannot slide, and because the hole angles down, it cannot rise out either.
Buy for the door you own, not for the reviews: the hook and the screw spacing have to match the panel in front of you. The best locks for sliding glass doors are covered on their own.
Take away the room a sliding door needs to be lifted out
Take hold of the handle and pull straight up. If the panel rises more than a little, there is room above it to clear the bottom track. That is how a locked slider comes out of its opening without anybody touching the lock.
Here is what is happening at the bottom of the panel. It sits on two small wheels, called rollers, and each roller has an adjusting screw that raises or lowers that corner of the door. New rollers carry the panel high enough that the top of its frame sits well up inside the top track. Rollers wear flat over the years, the panel settles lower, and the space at the top opens up.
So there are two fixes, and they do different things. Screws driven into the top track above the panel, or plastic anti-lift blocks clipped in up there, stop the panel rising. Set them so the door still slides freely. The other fix deals with why the space appeared: new rollers and a cleaned track put the panel back where it belongs, and worn rollers are the most common thing I replace on these doors.
A roller and track service runs around $405 on a standard patio door and around $635 on a large or heavy-panel one, supplied and fitted. Those are typical 2026 figures, not a quote, and the number moves with the size of the door and what the hardware turns out to be.
What film and a camera actually buy you
Neither of these keeps the door shut, so it is worth being plain about what each one does.
Security film is a clear plastic sheet you stick to the glass. Keep it on the inside face, where nobody standing outside can get a blade under the edge. Hit the glass and it still breaks, but the pieces stay stuck to the sheet instead of dropping out, so the hole somebody needs to reach the latch does not appear on the first swing. What you buy is time and noise. It does not make the glass unbreakable.
A door sensor or a camera resists nothing at all. It tells you that the door just opened, which is worth having when the house is empty, so long as it is not standing in for the bar and the pin.
What we check when we come out
A repair visit is for the part underneath all of that, where the door has stopped sitting right.
- How far the panel lifts, measured rather than guessed, and whether closing that up takes blocks in the top track or new rollers under it.
- Whether the latch goes fully into its keeper, which is the slot in the jamb it hooks into. A door out of adjustment feels locked and is holding on by the tip of the hook.
- Which locks physically fit your door, with the hook, the screw spacing and the plate measured off the panel you have.
Our work carries 6 months on the parts we supply and 1 year on our own installation. We handle rollers, tracks, locks, handles and alignment, and we do not sell alarms, cameras or film, so none of the three above comes with a product attached.
Frequently asked questions
Can I do any of this if I rent?
Most of it. A cut dowel or an adjustable bar in the track touches nothing and comes out when you move, and stick-on film and a battery door sensor are both reversible. What needs your landlord’s agreement is anything that makes a hole: the drilled pin, screws in the top track, and a foot bolt.
Will a bar or an extra lock trap us inside in a fire?
It can trap you, so settle that before you fit anything. A patio door is often a second way out of a bedroom. Seattle police make the point that a door like this has to open from the inside without a key to meet fire codes. Keep every device on the door hand-operated from inside, keep the dowel somewhere you can reach it in the dark, and add nothing keyed on the inside face.
Is a security screen door a real answer, or just for bugs?
A security screen for a sliding door is a different product from the insect screen that came with it. It is a framed steel or aluminum grille with a mesh a knife will not cut, and it locks on its own. It is the strongest thing on this page and the most expensive, which is why most people reach for the bar and the pin first.
Get your slider locking and sitting right
If the panel lifts, the latch only just catches, or the door drags so badly that nobody bothers locking it, hardware is not the fix.
JDM Sliding Doors handles sliding door repair, rollers, tracks, locks and handles across South Florida and our other markets. Send us a photo of the bottom track and the closing edge and we will tell you what it needs. Schedule a free repair estimate.
