Shelter ยท Gear Review
Best Sliding Door Locks. Three weak points, three small fixes.
A sliding glass door ships with a lightweight latch, and police guides recommend adding a second lock. The Prime-Line loop lock is the first thing to add: a steel loop that ties the door to the frame and flips open by hand from inside. A bar and an anti-lift bolt cover the rest.
At a glance: Prime-Line U 9847 loop lock
Strengths
- A steel loop that ties the sliding panel to the jamb, separate from the factory latch.
- It flips open by hand from inside, with no key.
- Thousands of owner ratings, averaging 4.6 stars when we checked.
- It costs about $11.
Limitations
- It mounts with screws into both the door and the jamb.
- Fit varies by door, so check the reach before you buy.
- Prime-Line does not claim it stops the door being lifted out.
- Some owners swap the supplied screws for a firmer mount.
The verdict
The slide, the brace, and the lift.
Our locks and door reinforcement handbook names three weak points on a sliding door. Each pick covers one, and every one opens by hand from inside, because a slider can be a way out in a fire.
Stops the slide
Prime-Line U 9847 loop lock
A steel loop from the door to the jamb. The first lock most sliders need.
About $11 to $12
A brace you can see
Ideal Security patio door bar
A bar across the opening that screws to the frame, with a vent setting. Bob Vila's pick for sliding doors.
About $26 to $29
Stops the lift
Prime-Line anti-lift bolt
A steel bolt that Prime-Line says prevents sliding or lifting, closed or vented. Or put screws in the upper track for nearly nothing.
About $8 to $12
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Why the pick wins
A second lock, not a stick.
Redmond police say every sliding door should have a second lock beyond its latch, and Seattle police recommend adding one. The loop lock is the simplest real one.
01
More than a dowel
The Chula Vista study rated dowels below channel and pin locks. No study we found tested loop locks, but a loop is fastened to door and frame, which a dowel is not.
02
Out in a second
The loop flips off its keeper by hand. No key to find, nothing to unscrew, in the dark or in a hurry.
03
Fastened, not wedged
It is fastened to the door and the frame, so it stays put where a loose stick can shift.
04
Widely owned
It carries thousands of owner ratings, averaging 4.6 stars when we checked, more than any other lock we considered.
Redmond, Washington police put it plainly: all glass sliding windows and doors should have secondary locking systems, a second way to lock them beyond the lightweight latch. (Redmond Police) The Chula Vista study behind our handbook rated dowel braces below channel and pin locks. (Chula Vista Police Department)
We found no lab that tests loop or pin locks. The pick rests on what the lock is: steel, mounted to the frame, keyless from inside, and owned by a large number of households who rate it well. Bob Vila's hands-on testing did cover security bars, and that result supports our second pick.
The picks
One for each weak point.
Start with the loop lock. Add the bar if you want a brace someone outside can see, and deal with the lift if your door is older or rattles in its track.
Stops the slide
Prime-Line U 9847 Sliding Door Loop Lock
A plated steel loop lock, listed at 2-1/8 inches, that Prime-Line describes as a secondary locking device that secures the door to the jamb. (Prime-Line) One piece screws to the edge of the sliding panel and the other to the jamb; close the door and flip the loop over, and it holds the sliding panel to the frame as a second lock beside the factory latch.
Check the fit before you buy against Prime-Line's line drawing, since it sells more than one size. Installation means drilling small pilot holes, and Prime-Line warns to make sure the drill and screws will not touch the glass. Prime-Line notes it can be mounted high to keep small children from opening the door; if you do that, make sure an adult is always home to open it, and plan another way out for children. Use longer screws into solid frame if the supplied ones feel loose.
Specifications
A brace you can see
Ideal Security Patio Door Bar with Anti-Lift Lock
An adjustable bar, model 110 in several finishes (BK110W is white), that swings down across the opening and is screwed into the door frame rather than wedged against the floor. Ideal lists a length of 25.75 to 47.5 inches, a setting that lets the door open partway for air while locked, and a childproof lock that keeps the bar from being lifted out of its saddle by children. (Ideal Security) Despite the name, that lock holds the bar, not the door, so it does not cover the lift.
In Bob Vila's hands-on test of ten door security devices, it was the pick for sliding doors: very easy to install and use, with an excellent strength-to-weight ratio. Testers found it holds against the push of a door being forced open but can bend under sideways force. (Bob Vila) It swings up by hand, so it does not slow a way out.
Specifications
Stops the lift
Prime-Line Anti-Lift Sliding Door Bolt Lock (U 9866)
A diecast aluminum slide bolt, 2-1/4 inches, with a hardened steel bolt. Prime-Line says it secures the door closed or in a ventilating position and prevents sliding or lifting. (Prime-Line) The bolt needs a hole to engage in the other frame, so drill only where you are sure of missing the glass, and follow the instructions in the package.
The no-cost alternative comes from police guides. Seattle police advise large flat-head sheet metal screws in the top track at both ends and in the middle, adjusted so the sliding panel still clears when slid shut. (Seattle Police) Redmond police note that sliding doors made before 1990 can be lifted out of the lower track at any position. This bolt has far fewer owner ratings than our other picks, so treat it as the option, and the screws as the default.
Specifications
What owners actually say
Simple hardware, careful installs.
These patterns come from retailer reviews. A theme appears here only when more than one owner raises it independently.
Prime-Line loop lock
Owners describe it as sturdy metal, and many bought it to replace a stick in the track.
The recurring cautions are that it takes care to line up so it latches smoothly, and that the supplied screws may not give a solid mount.
Ideal Security bar
Owners find it easy to install and like that it is plainly visible from outside.
The recurring complaints are a saddle bracket that sometimes needs trimming to fit, a thin base mount, and returns over length, so measure the opening first.
We did not find enough owner discussion of the anti-lift bolt to report patterns.
The one thing to know
A slider can be a way out.
Sliding doors often open from a living area, and sometimes from a bedroom. Anything you add to one has to come off fast, by hand, in the dark. Seattle police say window bars and grills in sleeping rooms should come off easily from the inside to comply with fire codes, and we hold anything on a slider to the same standard. (Seattle Police)
That is why every pick here opens without a key. Some police guides, including Chula Vista's and Redmond's, recommend keyed sliding door locks; we chose keyless ones because a slider can be an escape route. If you choose a keyed lock, keep the key in the lock or beside the door whenever someone is home. Show everyone in the house how each lock opens, and practice it at night. Our handbook's safety section covers escape routes for every door and window.
How they fail, what they cost
A one-time cost, and a few checks.
No batteries, no plan, no running cost. All three together cost about $45 to $53.
Screws that loosen
A lock is only as firm as its mount. Check the screws once a season, and replace short ones with longer screws into solid frame.
Frames that shift
Redmond police note that pin holes may stop lining up as frames wear. If a lock starts to bind, adjust it rather than leaving it off.
A lock left open
A common failure is a lock nobody engaged. Add the slider to the nightly locking routine, the same as the front door.
What we didn't pick
And who should skip these.
Keyed sliding door locks
Prime-Line and others sell keyed versions. Some police guides recommend them. On a door that may be a way out, a key is one more thing to find in the dark, so we chose keyless locks instead.
Pressure bars and dowels
The Chula Vista study rated braces such as dowels below pin and channel locks. A screwed-in bar is sturdier than one that only wedges in place, but no study we found tested either. Keep a dowel as a stopgap while the real lock is on its way.
Thumbscrew track clamps
They fit only some metal frames, and you have to loosen the thumbscrews to open the door, which is slow in an emergency. The one established model we found was also out of stock on Amazon when we checked.
If the glass is the worry
These locks stop the door sliding open; they do nothing about the glass. An alarm sensor on the door tells you when it opens; see our door and window alarm picks.
If you rent
Ask before drilling. Screws for the loop lock or the bar leave small holes; the upper-track screws leave holes hidden in the track; a dowel needs no permission at all.
If it is a hinged patio door
French and hinged patio doors fail like any hinged door: at the frame. Start with our door reinforcement picks.
Where it fits in your readiness
A first-weekend fix, for a few dollars.
Sliding door locks belong in the Survive tier: cheap, quick to install, and independent of power and internet.
Civil disruption
When things are unsettled nearby, the slider is often the easiest door in the house to open from outside. These locks close that gap.
Power outages
Nothing here needs power or batteries.
Maintenance
Once a season, two minutes.
- Engage each lock and push on the door; nothing should move.
- Tighten any loose screws, and replace short ones with longer screws into solid frame.
- Vacuum the bottom track so the door closes fully and the locks line up.
- Check that the upper-track screws still let the door clear.
- Have everyone in the house open each lock in the dark.
Questions people ask
Before you reach for the drill.
Is a dowel in the track enough to secure a sliding door?
It is better than nothing and costs nothing, but the Chula Vista police burglary study rated dowel braces less effective than channel or pin locks. Use one as a stopgap while a real lock is on its way. (Chula Vista Police Department)
Can a sliding glass door be lifted off its track?
Some can, especially older ones. Redmond, Washington police note that pre-1990 sliding doors can be lifted out of the lower track, and in the Chula Vista study burglars lifted sliding doors off their tracks in 12% of door-entry cases. Screws in the upper track or an anti-lift lock take away the room the door needs to come out. (Redmond Police; Chula Vista Police Department)
Is it safe to drill into a sliding door frame?
Only where you will not hit the glass. Redmond police advise drilling for a pin only if the frame can be drilled without damaging the thermal seal or glass, and Seattle police describe drilling only where there is no possibility of breaking the glass. All three picks need screw holes in the frame, so check each spot first. If you cannot tell, use upper-track screws and a snug dowel until someone who knows your door can look. (Redmond Police; Seattle Police)
Will a sliding door lock slow us down in a fire?
Any lock adds a step, so choose one that opens by hand with no key and the delay is a second or two. All three of our picks open that way. Seattle police say window bars and grills in sleeping rooms should come off easily from the inside to comply with fire codes, and we hold sliding door locks to the same standard. Show everyone in the house how each one opens, and practice it in the dark. (Seattle Police)