The Horrors
Deep Cut
Security Guide
Try The Window.
You spent real money on a good deadbolt. You read the reviews, you got the Grade 1, you drove the screws deep into the stud. And then you left the 1970s aluminum-frame slider cracked open in the bedroom because it was warm. The lock you obsessed over is irrelevant. Here's everything you're not thinking about.
By the NPZ Team
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Deep Cuts · Security
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March 2026
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15 Min Read
Security thinking has a front door problem. All the research, all the marketing, all the YouTube reviews, all of it converges on the primary entry door as if that's the only thing standing between your household and disaster. And it's not wrong, exactly — the front door is still the most common entry point. But it's also the entry point that people have been worrying about for decades. It has a deadbolt on it. It has a reinforced frame. It has a camera pointing at it. The door is, often, the most defended square foot of the entire house.
The windows have a latch. The sliding glass door has a bar — maybe. The garage has a hollow-core interior door that would fail in a single kick. The basement hopper windows sit two feet below grade, invisible from the street, never thought about. Security is only as strong as the weakest point in the perimeter, and for most homes, the weakest point isn't anywhere near the front door.
This piece covers every overlooked entry point — what makes each one vulnerable, how the vulnerabilities get exploited, and what actually fixes them. No expensive systems. Mostly cheap hardware and awareness.
23%
Of break-ins use a first-floor window
~⅓
Of window entries — no glass broken at all
$15
Cost to properly secure most windows
Before you can fix a weakness you have to know it exists. Here's the full map of entry points that routinely get ignored — rated by how easy they are to defeat without tools, noise, or skill. Five pips is worst.
Threat Level
The standard up-and-down residential window. The crescent-shaped flip latch it ships with is not a lock — it's a stay. It holds the sash closed against rattle and draft, not against forced entry. A flat-bladed tool inserted in the gap will defeat it in seconds. The sash can also be vibrated open on older frames where the latch fits loosely.
Threat Level
The worst window type for security. Most slide horizontally on a track, which means they can often be lifted completely off the track and removed without touching the latch. Old aluminum-frame sliders — extremely common in homes built before 1990 — have minimal track depth. Lift, tilt, pull. Twenty seconds. No noise, no broken glass.
Threat Level
Ties with sliding windows for worst-in-class. The standard latch is a hook that simply drops into a receiver — it provides minimal resistance to lateral force. The door also sits in a track, and many models can be lifted free of the track even when latched. Combine these two failure modes and you have what is, mechanically, the least secure commonly installed exterior door in residential construction.
Threat Level
Below-grade, hidden from the street, rarely alarmed, often old and rotten in the frame. A small hopper window is too tight for most adults — but a slim teenager isn't a small teenager. More importantly, entering through a basement hopper gives access to the interior stairwell, and from there, every interior door. The security value of the deadbolt on your front door does not help you here at all.
Threat Level
The issue isn't that someone crawls through — it's reach-through. A pet door installed in a door panel within 18 inches of the interior knob or deadbolt turn-piece is an invitation to reach in, grab the knob, and open the door. This happens. There are documented burglary cases specifically attributed to this. If the pet door is in a panel adjacent to a lever handle with no deadbolt, it's particularly dangerous.
Threat Level
The interior door connecting an attached garage to the house is, in most residential builds, the weakest door on the property. Hollow-core slab. Cheap knob lock. No deadbolt. No reinforced frame. Builders treat it as an interior door — which it would be, if the garage were perfectly secure. It isn't. One of the three most exploited residential vulnerabilities in attached-garage homes.
Threat Level
Low-probability but worth knowing: a door-mounted mail slot is a reach-through vector for interior knobs and lever handles. More practically, a mail slot provides a viewing angle into the entryway — useful to someone casing the property. If your mail slot is adjacent to any interior hardware, a cage or deflector box behind it is cheap insurance. It also stops the "fishing" technique used to snag keys left near the door.
Threat Level
The automatic garage door has two known attack vectors: the emergency release cord (accessible from outside via a wire hook through the top weather seal gap) and older fixed-code openers (vulnerable to code scanners). The release cord attack is the more common one and takes under 30 seconds. It doesn't require any tools beyond a wire hanger. This is a known, documented technique — and most people have never heard of it.
⚠ The Latch Isn't a Lock
This is worth saying directly: the crescent latch on a double-hung window, the hook receiver on a sliding glass door, and the spring-loaded clip on a sliding window are all latches, not locks. A latch holds a door or window in the closed position against wind, draft, and incidental contact. It provides minimal resistance against deliberate force. If you have never installed a secondary lock on your windows, you effectively have no window security — regardless of what the factory hardware looks like.
Why glass breaking isn't the main concern
Glass breaking is loud, produces evidence (shards, blood), and is psychologically difficult to commit in a residential neighbourhood at midday. The preferred approach to window entry is simply: find one that's unlocked or improperly latched and open it. Failing that, open it from the outside with a tool. Breaking glass is the method of last resort, not the first.
This changes your threat model entirely. You don't primarily need glass-break sensors — you need locks that prevent the window from opening even when attacked from the outside. Glass-break sensors are a supplement, not a substitute.
Double-hung windows: the sash pin fix
A double-hung window has two sliding sashes (panels). The most effective secondary lock is a sash pin — a long bolt that passes through a hole drilled at a downward angle through the inner sash frame and into (but not through) the outer sash frame. When the pin is in place, neither sash can be moved. Cost: about $3 per window. Time to install: ten minutes with a drill. This is, genuinely, one of the cheapest and most effective security improvements in residential security. Almost nobody does it.
If you want ventilation security — the ability to leave a window partially open while still preventing entry — drill a second set of holes at roughly 3–4 inches of opening. Insert the pin, and the window can vent but cannot be raised further. This is the "6-inch rule" applied properly: a gap sufficient for airflow but not passage. A 6-inch opening is not small enough on its own — an arm can reach through 6 inches. The pin is what makes that ventilation gap a fixed limit, not an invitation.
Sliding windows: the track block
For sliding windows, the first fix is a track bar — a cut-down piece of wooden dowel, aluminium bar, or purpose-made security bar laid in the track beside the closed panel. This prevents the panel from sliding even if the latch is defeated. For the lift-off problem, anti-lift pins or screws driven into the top track above the sliding panel prevent it from being lifted free. Together these two measures — costing under $5 in hardware — eliminate both primary attack vectors on a sliding window.
Keyed window locks
For windows in high-risk locations (ground floor, side of house, basement-adjacent), a keyed lock is worth considering. These replace or supplement the factory latch with a lock cylinder that cannot be defeated without the key or by breaking the glass. The obvious trade-off: in a fire, you need the key. If you install keyed window locks, the key should be stored immediately adjacent to each window — visible to you from inside, not accessible from outside. This is non-negotiable. A keyed window lock that slows your exit in an emergency is not a good outcome.
Window security film
Security film doesn't prevent window entry — it complicates it significantly. Applied to the glass surface, 4–8 mil security film keeps the glass intact under impact, turning a clean break into a struggle against a membrane that holds the shards together. It buys time and noise. It won't stop a determined attack, but for the opportunist who needs to be in and out quietly in under ten minutes, a window that won't break cleanly is a significant deterrent. It's also cheap — roughly $0.50–$1.50 per square foot — and provides secondary benefits (UV protection, glass retention in accidental breakage).
🔒 The Frame Is Often the Problem, Not the Glass
Old wooden window frames rot. Old aluminum frames fatigue and warp. When a window frame is deteriorated, the latch or lock mounted to it is only as good as the wood or metal it's anchored in. Before installing secondary locks on old windows, check the frame condition first. A sash pin in a rotten sill is not meaningful security. Sometimes the honest answer is: this window needs replacing before it can be secured.
The sliding glass door gets its own chapter because it combines multiple failure modes in a single opening. The standard patio door shipped with residential construction from the 1960s through the 1990s is, without exaggeration, one of the most insecure closures in any home. Modern doors are better — but the old ones are still out there on millions of properties, and even the newer ones are frequently not properly secured.
Failure mode 1: The latch
The standard latch on a sliding glass door is a hook — a spring-loaded or lever-actuated tab that engages a receiver in the door frame. It takes lateral force well enough, but the frame it mounts to is a thin aluminum extrusion that can flex under direct attack. A sharp kick to the door panel while simultaneously pulling the handle frequently defeats the latch on older doors without any tools. The fix is a secondary lock — either a foot-bolt (a bolt that drops into a hole in the track, preventing sliding) or a surface-mounted keyed lock that engages a strike plate in the frame rather than a simple hook-and-receiver.
Failure mode 2: Lift-off
Most sliding glass doors can be lifted off their bottom tracks and pivoted free when the top guide clears the upper track. This defeats any latch entirely — the door simply comes out rather than sliding. The fix is anti-lift hardware: either screws or purpose-made pins installed in the upper track above the door panel, reducing clearance so the panel cannot be lifted high enough to clear the bottom track. This is a ten-minute fix with a drill and three screws. It costs nothing if you have the hardware.
Failure mode 3: The track bar problem
The famous broomstick-in-the-track trick is real and genuinely works as a secondary security measure — but only if it's in the track, which requires actively placing it every single time. The problem is the same as every manually-operated security measure: it only works when you remember to use it. A purpose-made security bar with a non-slip end that wedges at the correct length is better than a cut dowel because it fits precisely and is easier to replace consistently. Even better: a foot-bolt or keyed floor lock that actively requires someone to disengage it, rather than a passive bar that can be forgotten.
The sliding glass door was designed for living convenience — indoor-outdoor flow, natural light, open-plan living. Security was an afterthought, if it was a thought at all. The original engineers were not thinking about entry vectors.
— NPZ assessment after inspecting 40+ residential patio door installations
✓ The Three-Fix Minimum for Any Sliding Glass Door
- Anti-lift pins or screws in the upper track — eliminates the lift-off attack. ~$8 in hardware.
- Secondary foot-bolt or keyed lock on the door panel — something that actively engages the frame, not just a hook. $15–$40.
- Alarm sensor on the door frame — a simple magnetic contact sensor that triggers if the door opens (or the panel moves). $10–$20 per sensor, works with any home alarm system or standalone chime. This is your backup for when you forget the bar.
If you have an attached garage, it is very likely the weakest part of your home's perimeter — and the weakness isn't always where you're looking. People think about the big roll-up door. The actual vulnerabilities are subtler and significantly more exploitable.
The emergency release cord attack
Every automatic garage door opener has a manually-operated emergency release cord — the red handle hanging from the trolley on the overhead track. This cord exists so you can disengage the drive mechanism and open the door by hand in a power outage. The problem: there is typically a gap of several centimetres between the top of the garage door and the door frame, and through that gap, with a coat hanger bent into a hook, a person can reach the emergency release cord and disengage it from the outside. The door can then be opened manually, silently, in under 30 seconds. This technique is so well-documented that it even has a name in the security community: "fishing."
The fix is simple: a zip tie looped through the release cord hole prevents the cord from being pulled far enough to disengage — while still allowing you to break it easily in an actual emergency. Alternatively, dedicated garage door shield covers block the top gap physically. The zip tie solution costs nothing and takes 60 seconds.
The interior passage door
Once someone is in your garage — whether through the roll-up door or otherwise — the next obstacle is the door from the garage into the house. In the majority of residential construction, this door is a hollow-core interior slab. Same hollow door used for bedroom doors. Same cheap knob lock. No deadbolt in most builds. No reinforced frame. This door would not survive a single serious kick.
This is the single highest-impact upgrade in any attached-garage home: replace the garage passage door with a solid-core exterior door, install a proper Grade 1 deadbolt, and reinforce the strike plate. Treat it exactly like a front door, because when someone is in the garage, it functionally is the front door. Cost for the full upgrade: $150–$300. Impact: eliminates what is often the easiest final step in a garage-based break-in.
Opener vulnerabilities
Older fixed-code garage door openers — those manufactured before roughly 1996 — transmit a single static radio code every time you press the button. Code grabbers that record and replay this signal have been commercially available for decades, and are still in use. If you have a garage opener from before the mid-1990s, this is a real vulnerability. The fix is replacement: any modern opener using rolling code (also called "Security+" or "Intellicode" depending on brand) changes the code after every use, making code interception useless.
Modern rolling-code openers are not significantly vulnerable to signal attacks under normal use — but they do have a known weakness related to jamming: some older implementations can be jammed to prevent the code from advancing, then have the intercepted code replayed. This is a sufficiently technical attack that it's largely irrelevant to the residential threat model, but worth knowing if you're in a high-risk area.
⚠ Leave a Spare Remote in the Car? Read This.
A garage remote left visible in an unlocked car is a master key to your home — it opens the garage and, if the passage door isn't properly secured, the house. Car break-ins are far more common than home break-ins. A stolen garage remote combined with the registration document also in the glovebox gives an attacker your address and the means to enter the garage at their convenience. Keep remotes out of sight. Consider a smartphone-based opener app instead of a physical remote if your opener supports it.
✓ The $100 Weekend That Changes Everything
Sash pins for every double-hung window ($20 in hardware). Track bars and anti-lift screws for every slider and sliding glass door ($25). A zip tie on the garage door release cord ($0). Magnetic contact alarm sensors on the two most exposed ground-floor windows ($25). Solid lock on the garage passage door if it doesn't have one ($35). That's a weekend of work and about $100 that addresses more of your actual risk surface than a $600 smart security system installed on a front door that was already your most defended entry point.
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We've established that breaking glass is not the first-choice method. But it happens, and it's worth understanding what the options are when someone is willing to make noise.
Standard float glass
Single-pane float glass — what's in most older residential windows — shatters into large, sharp shards. A single strike from a hard object is sufficient. It is fast, it is loud (though less loud than people assume at distance), and it leaves significant evidence. The break takes under a second. The noise risk is real but often overestimated — a short, sharp impact at 1am in a suburban neighbourhood may not register distinctly with neighbours who are asleep with fans or white noise running.
Tempered glass
Standard in sliding glass doors and most exterior doors with glass panels. Tempered glass doesn't shatter into large shards — it breaks into small, relatively dull fragments. It's more resistant to simple impact than float glass, but a centre-punch tool applied to a corner defeats it instantly. The fragment pattern is actually advantageous for an intruder: small cubes are far easier to step over than large shards. Tempered glass is not a meaningful security upgrade over standard glass.
Laminated glass
The meaningful upgrade. Laminated glass has a plastic interlayer between two panes that keeps the glass intact even after it breaks. Breaking through laminated glass requires sustained hammering — not a quick impact. The noise, time, and physical effort required are substantial. This is the glass in car windshields; it's the glass in hurricane-rated windows. The trade-off is cost: laminated glass windows cost significantly more than standard, which is why they're an upgrade rather than a default. For a small number of high-risk openings — ground-floor sliding doors, accessible basement windows — the cost can be justified.
Security film on existing glass
Security film is the cost-effective version of laminated glass for existing installations. Applied professionally to the inside face of existing glass, 8-mil security film mimics the interlayer effect of laminated glass at a fraction of the cost. It won't stop sustained attack with the right tool, but it raises the time and noise required for entry significantly. Self-adhesive film kits are available for DIY application at around $1–$2 per square foot. Professional installation is worth it for large panels (patio doors, floor-to-ceiling windows) where bubbles and edges matter more.
Glass break sensors
Acoustic glass break sensors detect the specific sound frequency profile of breaking glass and trigger an alarm. They work well when positioned correctly — typically within 15–20 feet of the protected glass in an open room. They're less useful in rooms with soft furnishings that absorb sound, behind heavy curtains, or in complex layouts. They should be treated as a supplementary layer, not a primary one: a glass break sensor plus a keyed window lock is a much better combination than a glass break sensor alone. The sensor catches what your lock didn't prevent.
⚡ Window Film + Contact Sensor = Better Than Either Alone
Security film slows the glass break. A magnetic contact sensor on the window frame detects the opening. If someone breaks through the film and opens the window, both systems have triggered at different stages of the same attack. This layered approach — mechanical delay plus electronic detection — is more effective than either measure alone and costs under $30 per window combined. This is the correct way to think about window security: not one expensive solution, but multiple cheap ones working together.
The Bottom Line
Security Ends Where Your Attention Does
The pattern in every chapter of this article is the same: the overlooked entry point isn't poorly understood by the security industry. The fixes are cheap, documented, and available everywhere. The problem is that nobody thinks about the window until after something happens to the window. The front door absorbs all the mental and financial energy, and everything else gets a factory latch and a vague feeling that it's probably fine.
It's not. A $200 deadbolt on the front door and a 1970s aluminum slider with no secondary lock is a $200 investment in your weakest point and zero investment in your most vulnerable one. Rebalance the spending. Spend the $100 weekend on the perimeter before you spend another dollar on the door.
And for the garage passage door — the one connecting an attached garage to your house — treat it like the exterior door it functionally is. Install a solid-core slab. Install a deadbolt. Reinforce the frame. If someone gets into your garage, which is not that hard, that door is what stands between them and your home. Right now, in most houses, it's the interior door equivalent of a screen door on a submarine.
Check our Home Security Setup guide for the full room-by-room walkthrough, and our deadbolt reviews for what to put on the doors you've now realized you need to take seriously.
