Shelter · Home Security
Window security. The overlooked entry point.
Pin locks, security film, glass-break sensors, and basement window protection. What the data shows about window entries, what actually slows them down, and where a $5 fix closes the gap.
By Dan Whelan, founder of New World Survival
Researched from government agencies, university extension services, and other published sources. See our sources
Why windows matter
Windows are involved in nearly half of forced entries.
Bureau of Justice Statistics data on household burglary shows that a window, through a broken pane, a removed screen, or a defeated latch, was the way in for about 49% of forced-entry burglaries of empty homes. When someone was home, the figure was similar, about 47%.1
Most homeowners focus their security spending on doors. That makes sense: doors are the single most common entry point. But windows are the second most common, and they often receive no upgrades at all. The factory latch on most residential windows is a convenience feature, not a security device.
The upgrades on this page are ordered by cost and impact. The first two, secondary window locks and locking habits, cost under $10 per window and address the majority of residential window vulnerabilities.
What this page covers
Window locks by type
Pin locks, sash locks, keyed locks, and track locks. Which lock fits which window, and why the factory latch is not enough on its own.
Security film
How film thickness affects protection, what the standards mean, and how it fits into a layered approach. It does not make glass unbreakable, but it changes the math.
Glass-break sensors and alarms
Acoustic sensors, vibration sensors, and contact sensors. What each type detects, where to place them, and how they work with a home alarm system.
Basement and ground-floor windows
The highest-risk windows in most homes. Window well covers, bars with quick-release mechanisms, and how to balance security with fire egress requirements.
What this page does not cover: firearms, physical confrontation, or force options. Window security is a deterrence and delay layer. For the full security framework, see the seven layers of home security.
Window locks
The factory latch is a starting point, not a solution.
Most residential windows ship with a crescent latch or cam lock. These are designed to hold the window closed against weather, not resist prying. A secondary lock addresses the gap for a few dollars per window.
Pin locks (double-hung windows)
A pin lock is a metal pin or nail inserted through a hole drilled at an angle through the inner sash and partway into the outer sash. When the pin is in place, the window cannot be lifted. When it is removed, the window operates normally.
This is the highest-return secondary lock for double-hung windows. The technique has been recommended by police departments and CPTED practitioners for decades.
Cost: $3 to $10 per window. Time: 10 minutes with a drill.
Sash locks (double-hung windows)
Sash locks clamp the two sashes together, reinforcing or replacing the factory crescent latch. Some models are keyed, which prevents the lock from being turned if someone breaks a small pane and reaches inside. Keyed sash locks create the same fire-egress concern as double-cylinder deadbolts: keep the key accessible to household members.
Cost: $8 to $25 per window. Time: 15 to 20 minutes.
Track locks (sliding windows)
Sliding windows use the same principle as sliding glass doors: the factory latch can often be defeated by lifting or prying. A track lock, a thumbscrew-style clamp installed in the track, prevents the window from being forced open. A wooden dowel or metal rod cut to the track length costs nothing, but a Chula Vista police study found dowel braces on sliding glass doors less effective than channel or pin locks. Treat a dowel as a stopgap and add a track lock.2
Cost: $0 (dowel) to $12. Time: 5 minutes.
Casement window locks
Casement windows crank open outward and pull tight against the frame when closed. This design makes them inherently harder to force from the outside because pressure pushes the window further into its seal. The factory locking mechanism is usually adequate for casement windows.
Priority: Lower than double-hung or sliding. Verify the crank and latch work smoothly.
Ventilation locks
Pin locks can be installed at a second drill point a few inches above the closed position, allowing the window to open for airflow but not wide enough for entry. This is particularly useful in bedrooms during warm months when you want ventilation without leaving windows fully accessible.
Cost: Same as a pin lock. Drill two holes instead of one.
Keyed window locks
Keyed locks prevent the window from being opened even if someone breaks glass and reaches the latch. They are most useful on ground-floor windows with small panes next to the lock, where breaking one pane gives access to the latch mechanism. The trade-off is the same as any keyed lock: occupants need the key to exit through that window in a fire.
Cost: $15 to $30 per window.
The renter question
Pin locks, track dowels, and most sash locks require no permanent modification to the window frame beyond a small drill hole. Many landlords approve these improvements when asked, because they protect the property. Some municipalities require landlords to provide functioning window locks on all units.
If your lease prohibits drilling, adhesive-mount window locks are available. They are less effective than drilled alternatives, but they provide some resistance and can be removed at move-out without damage.
Security film
Film does not stop glass from breaking. It stops glass from opening.
Security window film is a clear polyester layer applied to the interior surface of a window. When the glass is struck, it shatters but stays held together by the film instead of falling out of the frame. The window is broken, but the opening is not clear.
Film thickness and what it means
4 mil
Basic safetyHolds glass together against accidental impact, such as a ball hitting a window or a child falling against one. Not designed for security applications, but better than bare glass.
8 mil
Residential securityThe most commonly recommended thickness for residential break-in delay. The broken glass stays in the frame and has to be beaten or cut through, which adds time and noise. It does not stop a determined person, and specific delay times quoted in product marketing are worth treating with caution.
12 to 15 mil
Commercial / stormDesigned for hurricane zones (tested to ASTM E1886/E1996 for windborne debris) and commercial storefronts. Higher cost and thicker appearance. Generally more protection than most residential applications require.
Standards that matter
ANSI Z97.1: The American National Standard for safety glazing. Film meeting this standard has been tested for impact resistance and fragment retention. Look for this on any security film you buy.3
CPSC 16 CFR 1201: The federal safety standard for glass in doors, sliding glass doors, and other locations where people can fall into it. It is an injury-safety test, not a burglary test. Category I glazing passes a 150 foot-pound impact test; Category II, required for sliding glass doors and large panels, passes a 400 foot-pound test. If a film lists a category, Category II is the higher level.4
GSA TS01: A General Services Administration standard for blast mitigation on federal buildings. Residential buyers do not need this level of certification, but it provides a benchmark for understanding film performance at the highest level.
Installation
Security film can be applied as a DIY project or by a professional installer. Professional installation typically costs $6 to $14 per square foot and ensures full coverage without bubbles or gaps at the edges.
For maximum effectiveness, the film should be anchored to the window frame with a structural sealant, not just applied to the glass surface. Without frame anchoring, the filmed glass can be pushed out of the frame as a single sheet. Professional installers typically include this step.
1 Bureau of Justice Statistics. "Victimization During Household Burglary." BJS Special Report, NCJ 227379, September 2010. National Crime Victimization Survey data for 2003 to 2007, Tables 1, 5, 7, and 9. 2 Chula Vista Police Department. "The Chula Vista Residential Burglary Reduction Project." Herman Goldstein Award submission, 2001, Center for Problem-Oriented Policing. Review of 569 burglarized or attempted homes, plus interviews with more than 300 victims and offenders. Sliding door braces such as wooden dowels were among the measures with relatively low effectiveness. 3 ANSI Z97.1: American National Standard for Safety Glazing Materials Used in Buildings. Safety Performance Specifications and Methods of Test. 4 Consumer Product Safety Commission. 16 CFR Part 1201: Safety Standard for Architectural Glazing Materials (ecfr.gov), including the 150 and 400 foot-pound impact levels for Categories I and II. Accessed October 2026.
Detection
Locks and film delay. Sensors detect.
Window sensors add the detection layer: they tell you when a window is opened or broken. Combined with locks and film, they create a three-part system: resist, delay, alert.
Acoustic glass-break sensors
These sensors listen for the specific frequency pattern of breaking glass. A single sensor can typically cover multiple windows in a room, up to about 20 to 25 feet in any direction. They trigger when glass actually breaks, not when a window is opened.
Best for: Rooms with multiple windows. One sensor covers the whole room. Cost: $20 to $50 per sensor.
Vibration sensors (shock sensors)
Mounted directly on the glass, these detect the vibration pattern of an impact before the glass fully breaks. They provide earlier warning than acoustic sensors but must be installed on each individual pane. Sensitivity adjustment is important to avoid false alarms from heavy wind or nearby traffic.
Best for: Individual high-value windows, such as large ground-floor panes. Cost: $15 to $35 per sensor.
Contact sensors (open/close)
A two-part magnetic sensor: one piece on the window, one on the frame. When the window opens and the magnets separate, the sensor triggers. These detect the window being opened, not the glass being broken. They are the simplest and most common type, and many home alarm systems include them.
Best for: Windows that might be pried open rather than broken. Cost: $10 to $30 per sensor.
Choosing a sensor type
Most households benefit from a combination. Contact sensors on ground-floor windows that open (these catch prying and sliding attempts), plus one acoustic sensor per room to cover glass breakage across multiple windows. The acoustic sensor eliminates the need to install individual vibration sensors on every pane.
Standalone sensors with built-in sirens are available for households without a monitored alarm system. The siren alone is a deterrent: the UNC Charlotte burglar study found that audible alarms caused 60% of surveyed burglars to move to a different target.5
5 Kuhns, Joseph B., Kristie R. Blevins, and Seungmug Lee. "Understanding Decisions to Burglarize from the Offender's Perspective." University of North Carolina at Charlotte, 2013. Funded by the Alarm Industry Research and Educational Foundation.
High-risk windows
Basement and ground-floor windows need the most attention.
Windows that are at ground level or below grade are the easiest to reach, the least visible to neighbors, and the most commonly targeted after doors. These are the windows where security upgrades have the highest return.
Basement window wells
Window wells create a recessed space below grade that provides both access and concealment. A person working in a window well is often invisible from the street and from neighboring properties.
Window well covers (clear polycarbonate or metal grate) address this by making the well visible from above and adding a physical barrier. Look for covers that are secured with hardware rather than simply resting on the well rim. A cover that can be lifted off by hand provides concealment benefit but no physical resistance.
Fire egress: Window well covers must open from the inside without tools. Building codes in most jurisdictions require this. Check that any cover you install has an interior release mechanism, and test it after installation.
Window bars and grilles
Window bars are the most physically effective window security measure. They prevent entry even if the glass is completely removed. They are most common on basement windows and ground-floor windows in urban areas.
The critical requirement is a quick-release mechanism on the interior side. Fixed bars that cannot be opened from inside create a fire trap. The International Residential Code requires that emergency egress windows remain operable from inside without keys, tools, or special knowledge.6
Quick-release bars use a lever or latch on the interior that swings or slides the bars open. Verify the release works smoothly, and make sure every household member knows how to operate it.
Cost: $50 to $200 per window for bars with quick-release hardware.
Glass block windows
Glass block is a common replacement for standard basement windows, particularly in older homes. Glass block windows allow light in but cannot be opened, and they are extremely difficult to break through. They provide excellent security for basement windows that do not serve as egress.
The trade-off: glass block windows do not open, so they cannot serve as fire egress. Building codes require at least one egress window in every basement bedroom. Glass block is appropriate for non-egress basement windows only.
Landscaping and visibility
Crime Prevention Through Environmental Design (CPTED) research consistently identifies natural surveillance as one of the most effective crime deterrents. For windows, this means maintaining clear sightlines between the window and the street, sidewalk, or neighboring properties.7
Trim shrubs near ground-floor windows to 3 feet or shorter. Dense, tall landscaping directly below windows provides concealment for someone working on the window. Thorny plants (holly, barberry, rose bushes) planted beneath windows add a natural deterrent without blocking sightlines.
6 International Code Council. International Residential Code (IRC), Section R310: Emergency Escape and Rescue Openings. Requires operable egress windows in sleeping rooms and basements with habitable space. 7 Cozens, Paul, Greg Saville, and David Hillier. "Crime Prevention Through Environmental Design (CPTED): A Review and Modern Bibliography." Property Management, vol. 23, no. 5, 2005.
What the research shows
Most window entries start with an unlocked window.
Before investing in film, sensors, or bars, the single most effective step is the one that costs nothing: lock every window, every time.
Unlocked entry is common
In the national crime victim survey, about a third of completed household burglaries came through a door or window that was open or unlocked.1 When no one was home, an unlocked door or window was the way in for about 40% of burglaries without force. Locking habits remain the foundation.
Speed matters
Research on offender decision-making shows that most residential burglars spend very little time attempting to gain entry. The UNC Charlotte study found that 41% described their crimes as impulsive.5 A window that resists the first attempt, makes noise, or takes longer than expected to breach is often abandoned in favor of an easier target.
Visibility is protective
CPTED research consistently shows that windows visible to the street, to neighbors, or to foot traffic are targeted less often than concealed windows.7 Ground-floor windows hidden behind tall shrubs or fences, side windows not visible from the front, and basement windows in window wells are the highest-risk locations.
The layered approach
No single window upgrade provides complete protection. Each layer adds time and complexity to an entry attempt. The combination is what matters.
Locking habits. Lock every window every time you leave and every night. Cost: $0.
Secondary locks. Pin locks on double-hung windows, track locks on sliders. Cost: $3 to $15 per window.
Security film on ground-floor and basement windows. Delays forced entry. Cost: $6 to $14 per square foot installed.
Sensors. Contact sensors on operable windows, acoustic sensors for glass breakage. Cost: $10 to $50 per sensor.
Physical barriers. Window bars with quick-release, glass block on non-egress basement windows. Cost: $50 to $200 per window.
Window security audit
Walk through every window in your home.
Start with ground-floor and basement windows. These are the highest priority. Most issues can be addressed in an afternoon.
Does every window have a working factory latch?
Test each one. A latch that does not fully engage, or that can be jiggled open, needs repair or replacement before any other upgrade.
Do ground-floor double-hung windows have secondary locks?
Pin locks or sash locks. The factory crescent latch alone is not sufficient for windows accessible from ground level.
Do sliding windows have a track lock or dowel?
Include sliding glass doors. A commercial track lock or pin lock prevents forced sliding; a cut dowel is a stopgap.
Are basement window wells covered and secured?
Covers should be fastened, not resting loose. Verify that any cover over an egress window can be opened from inside without tools.
If window bars are installed, do they have quick-release mechanisms?
Fixed bars without interior release violate fire egress codes in most jurisdictions and create a life-safety risk. Test the release mechanism regularly.
Are shrubs near ground-floor windows trimmed to 3 feet or less?
Dense landscaping below windows provides cover for someone working on the window. Maintain clear sightlines from the street and from neighbors.
Do you lock every window every time you leave and every night?
This is the single most effective window security measure. It costs nothing and addresses the most common entry method: walking up and checking for unlocked windows.
Common mistakes
Five things that waste money or create risk.
Installing fixed window bars without interior release
Fixed bars that cannot be opened from inside are a fire hazard. Building codes require emergency egress from sleeping rooms and habitable basements.6 If bars are installed, they must have a quick-release mechanism operable from inside without tools or keys. Test it after installation and periodically afterward.
Relying on security film without frame anchoring
Film applied only to the glass surface can be defeated by pushing the filmed glass out of the frame as a single sheet. Professional-grade installation includes a structural sealant that bonds the film to the window frame, holding the glass assembly in place even after impact. Without this step, the film provides fragment retention but limited forced-entry resistance.
Securing front windows but ignoring side and rear windows
Windows not visible from the street are targeted more often because they offer concealment. Side-yard windows, back-of-house windows, and windows screened by fences or landscaping need the same attention as street-facing windows. In many cases, they need more.
Choosing keyed window locks without a fire-safety plan
Keyed window locks prevent someone from reaching through broken glass to turn the latch. But they also prevent occupants from opening the window quickly in a fire. If you install keyed window locks, keep the key on a hook near the window, accessible to household members but out of reach from broken glass. Make sure everyone in the household knows where the key is.
Spending on sensors before fixing the locks
A glass-break sensor that alerts you to a broken window is useful. But if the window next to it was unlocked and the entry happened silently through the unlocked window, the sensor provided no value. Locks and locking habits come first. Sensors are the detection layer on top of the physical layer, not a substitute for it.
Related guides
Windows are one layer.
Window security is most effective when combined with the other layers of residential security: doors, lighting, habits, and awareness.
Door Security
Deadbolts, strike plates, and door frames. The highest-return upgrades for the most common entry point in residential break-ins.
The Layers of Home Security
The full framework: property, lighting, locks, alarms, cameras, habits, and community. Windows sit across multiple layers.
Security Without Paranoia
The evidence-based case for calm, layered home security. Start here if you want the full picture before going deep on any one topic.
Daily Security Habits
The routines that close the gaps hardware cannot. Locking discipline, window checks, and the habits that make every upgrade effective.
Common questions
The questions that come up most.
What percentage of burglaries involve entry through a window?
In Bureau of Justice Statistics data on forced-entry burglaries of unoccupied homes, a window was a point of entry in about half of cases and a door in nearly three-quarters, with some burglaries involving both. A damaged or removed pane accounted for 30 percent of all forced-entry methods, screen removal about 9 percent, and window lock tampering about 8 percent. Doors lead, but windows are the second most common way in, and many window entries succeed through an unlocked sash rather than broken glass.
Does window security film actually prevent break-ins?
Security film does not make glass unbreakable, but it holds shattered glass together and delays entry. 8-mil film is the most common residential recommendation. The broken glass stays in place, which adds time and noise to a forced entry. For forced-entry resistance, the film should be anchored to the frame with a structural sealant; without anchoring, the whole filmed pane can be pushed out.
What is the best window lock for home security?
The best window lock depends on your window type. For double-hung windows, a pin lock drilled through the inner sash into the outer sash is the most effective secondary lock, costing $3 to $10 per window. For sliding windows, a track lock or pin lock prevents the window from being forced open; the Chula Vista police study found wooden dowels in the track far less effective than channel or pin locks. For casement windows, the built-in locking mechanism is already strong because of how the window seats against the frame when closed. The key principle for all types: the factory latch alone is rarely sufficient for security. A secondary lock addresses the gap.