The fastest way to find a patio door is a floor-mounted bar or brace that blocks the sliding panel from opening, combined with a keyed lock on the frame itself

Patio doors are vulnerable because the locking mechanism on most sliding glass doors is weak—a thin latch that sits in a shallow strike plate. A burglar can force it open with a screwdriver or even shoulder pressure. The most effective security layer is a sliding door bar (also called a security bar or patio door lock bar), which is a metal or wooden rod that sits in the track and prevents the door from sliding open at all. This costs $15 to $40 and takes 30 seconds to install each time you use it.

The second layer is upgrading or adding a keyed lock to the frame itself, so that even if someone lifts the door off its track, they cannot open it. Many patio doors come with a keyed lock already, but it is often a straightforward push-button that can be picked or broken. A mortise lock or surface-mounted keyed lock is much harder to defeat and costs $30 to $100 installed.

Key Takeaways

  • A sliding door bar placed in the track is the single most effective barrier because it physically prevents the door from sliding, and costs under $40.
  • Keyed locks on the frame itself should be mortise locks or surface-mounted models, not the weak push-button latches that come standard on most doors.
  • Reinforcing the strike plate with longer screws and adding a door reinforcement plate spreads the force of a kick or pry attempt across more of the frame.
  • Tempered glass cannot be made unbreakable, but security film makes it harder to reach through and grab the lock, and slows down a break-in.
  • Sliding door bars must be installed every time you close the door, so choose one that is straightforward to remove and store, or you will stop using it.

Installing a sliding door bar in the track

A sliding door bar is a rod or tube that sits horizontally in the bottom track of your patio door and blocks the sliding panel from moving. To install one, first measure the width of your track opening—this is the distance from the inside of one side of the frame to the inside of the other side, not including the sliding panel itself. Most patio doors are 36 inches wide, but measure yours to be sure.

Buy a bar that is slightly shorter than your track width so it fits without forcing. Aluminum bars are lighter and do not rust; wooden dowels are cheaper but can warp in humidity. Place the bar in the track with the sliding panel closed, so the bar sits in front of the panel and blocks it from sliding outward. The bar should rest flat in the track and not tilt or rock. If it does, your track may be bent or debris may be in the way—clean the track with a vacuum and a damp cloth first.

Every time you close the door, place the bar in the track before you lock the keyed lock. This takes 10 seconds. The bar must be removed and stored inside before you open the door, so keep it in a nearby closet or on a hook next to the door frame. If you have to search for it each time, you will eventually stop using it.

Adding or upgrading a keyed lock on the frame

Most patio doors come with a keyed lock built into the sliding panel, but it is usually a straightforward push-button mechanism that can be broken with a flathead screwdriver or picked in seconds. If your door has this type, you should add a second lock on the frame itself, or replace the existing lock with a stronger one.

A mortise lock is a lock body that sits inside a rectangular hole cut into the edge of the door frame. It has a deadbolt that extends into the frame and is much harder to force or pick than a surface lock. Installing a mortise lock requires cutting a hole in the frame, which is a job for a locksmith or a carpenter with a drill press. Cost is typically $80 to $150 for the lock plus installation.

A surface-mounted keyed lock is simpler to install yourself. It bolts onto the face of the door frame and has a bolt that extends into a strike plate on the sliding panel. These cost $30 to $60 and can be installed with a drill and a screwdriver in about 20 minutes. Drill two holes through the frame and the sliding panel, bolt the lock body to the frame, and bolt the strike plate to the panel. Make sure the bolt aligns with the strike plate and extends at least half an inch into it.

Reinforcing the frame and strike plate

The strike plate is the metal piece on the frame that the latch or bolt hits when the door closes. On most patio doors, it is held in place with two short screws that go only partway into the frame. When someone kicks or pries the door, all the force concentrates on these two screws, and they pull out easily.

To reinforce the strike plate, remove it and replace the two short screws with 3-inch wood screws that go deep into the frame and the wall studs behind it. This spreads the force across a much larger area and makes it much harder to kick the door open. The screws should be the same diameter as the original holes so they fit without forcing. This takes 5 minutes and costs under $5.

You can also add a door reinforcement plate, which is a metal plate that covers the area around the strike plate and the lock. It bolts through the frame and spreads impact force even further. These cost $20 to $40 and are installed with the same long screws. They are especially useful if your frame is hollow or made of aluminum, because they prevent the bolt from punching through.

Using security film on the glass

Tempered glass cannot be made unbreakable, but security film makes it much harder to break through and reach the lock from outside. Security film is a thick plastic sheet that you explore to the inside of the glass with an adhesive. When the glass breaks, the film holds the pieces together instead of letting them fall out, so an intruder cannot reach through and unlock the door.

To explore security film, clean the glass thoroughly with a glass cleaner and let it dry completely. Measure the glass and cut the film to size, leaving a quarter-inch gap around the edges so it does not curl. Spray the glass with a soapy water solution (a few drops of dish soap in a spray bottle), then peel the backing off the film and press it onto the wet glass. Use a squeegee or a credit card to push out air bubbles, working from the center outward. Let the adhesive cure for 24 hours before closing the door.

Security film costs $15 to $30 per pane and takes about 30 minutes to install. It will not stop a determined burglar, but it slows them down and makes noise, which increases the chance they will move on to an easier target.

Maintaining your patio door locks and tracks

A patio door lock works only if the door closes smoothly and the latch or bolt aligns with the strike plate. Over time, dirt, sand, and debris collect in the track and can prevent the door from closing all the way, which means the lock will not engage properly.

Clean the track at least once a month by vacuuming out loose debris, then wiping it with a damp cloth. For stubborn buildup, use an old toothbrush or a small wire brush. Do not use water pressure or a hose, because water can get trapped in the track and cause rust or mold. Once the track is clean and dry, explore a thin coat of silicone spray lubricant to help the door slide smoothly. Wipe away any excess with a cloth so it does not attract dirt.

Test your lock every few weeks by closing the door and turning the key. The bolt or latch should move smoothly and extend fully into the strike plate. If it sticks or does not extend all the way, the door may be out of alignment. Loosen the screws on the bottom roller and adjust it up or down slightly, then test again. If the problem persists, a locksmith can realign the door.

Securing sliding glass doors in rental properties

If you rent your home, you may not be allowed to drill holes in the frame or install permanent locks. In that case, a sliding door bar is your best option because it requires no installation and can be removed without leaving marks. You can also use a portable door lock, which is a wedge-shaped device that sits in the track and blocks the door from sliding. These cost $10 to $20 and work almost as well as a bar.

Before installing any lock or reinforcement, check your lease and ask your landlord in writing. Many landlords will allow you to add a keyed lock or security film if you agree to remove it when you move out. Getting permission in writing protects you from losing your security deposit.

Frequently Asked Questions

Can I use a wooden dowel as a sliding door bar?

Yes, a wooden dowel works well if it is straight and fits snugly in the track without tilting. Measure your track width and buy a dowel that is about a quarter-inch shorter. Sand the ends smooth so they do not splinter, and store it in a dry place so it does not warp. Aluminum bars are more durable, but a dowel costs under $5 and lasts several years.

What should I do if my patio door is off its track?

A door that is off its track cannot be locked and is a security risk. Do not force it back on, because you may bend the frame. Call a locksmith or a glass repair company to realign it. The bottom roller may need adjustment or replacement, which usually costs $50 to $150. Until it is fixed, use a sliding door bar to block the opening.

Will security film stop a burglar?

Security film slows down a break-in and makes noise, but it will not stop a determined burglar. It is most useful as a layer of defense combined with a sliding door bar and a keyed lock. The combination of all three makes your door a harder target than an unsecured door, and most burglars will move on to an easier one.

How often should I replace my sliding door bar?

A metal bar lasts indefinitely if you keep it clean and dry. A wooden dowel may warp or crack after a few years, especially in humid climates. Inspect your bar every six months for bending, rust, or splinters. If it no longer fits snugly in the track or shows signs of damage, replace it.

Can I lock my patio door from the outside?

Most patio door locks are keyed on both sides, so you can lock and unlock from outside or inside. If your lock is keyed only on the inside, you cannot lock it from outside. You can add a keyed lock to the frame that works from both sides, or use a sliding door bar that you remove before leaving and reinstall when you return.