Laminated glass is the most effective window security upgrade because it holds together when struck. Auxiliary pin locks and anti-lift blocks on sliding units are the cheapest meaningful improvements. Standard tempered glass offers essentially no resistance.
Most residential window security spending goes to alarm sensors, which tell you after the fact. The upgrades that actually slow or stop an entry attempt are less well known and frequently cheaper.
Here is what works, ranked, with honest limits.
Ranked by effectiveness
| Upgrade | Cost | What it does |
|---|---|---|
| Laminated glass | $150 to $400 per sash extra | Holds together when struck, defeats smash and reach |
| Auxiliary pin lock on sliders | $15 to $40 | Stops the panel sliding even if the latch is defeated |
| Anti-lift blocks in the head track | $10 to $30 | Stops a slider being lifted out of its track |
| Keyed sash locks on double hungs | $20 to $50 | Prevents opening after glass is broken near the lock |
| Window opening limiters | $20 to $60 | Restricts travel, also a child safety item |
| Security film on existing glass | $8 to $20 per sq ft | Helps, but only as good as its edge attachment |
| Laminated storm window over original | $250 to $500 | Adds a second layer on historic windows |
| Standard tempered glass | Included | Essentially no security value, breaks into small pieces easily |
Why tempered glass is not security glass
This confuses people because tempered glass is described as safety glass and is required by code near doors and floors. Safety in that context means it breaks into small dull fragments rather than large sharp shards, which protects people from injury. It does not mean it is hard to break. Tempered glass actually shatters completely when it fails, clearing the entire opening in one impact, which from a security standpoint is worse than annealed glass that breaks into pieces still held in the frame. If you want security from the glass, the answer is laminated, not tempered.
Sliding windows and patio doors are the weak point
The classic method of entry on a sliding unit is not breaking glass, it is lifting the panel out of its track. Sliding panels sit in a bottom track with clearance in the head track above, and that clearance is what lets the panel be installed. It also lets the panel be lifted up and out from the outside, with the latch still engaged, in a few seconds and near silently. Two cheap items eliminate it. Anti-lift blocks screwed into the head track reduce the clearance so the panel cannot rise far enough to clear the bottom track. An auxiliary pin lock, which is a simple pin through both the moving and fixed panels, stops lateral movement independently of the latch. Together they cost under seventy dollars and they close the most commonly exploited residential opening.
What about security film?
Applied film on existing glass does help, and it is far cheaper than replacing glass. The important caveat is the edge. Film applied only to the glass surface will simply peel away from the frame under impact, taking the broken glass with it as a sheet, which still clears the opening. Film that is mechanically attached to the frame, either with an edge-anchoring system or wet-glazed into the frame, performs much better because the film has something to pull against. If a film quote does not mention edge attachment, the product is mostly cosmetic reassurance.
Ranges reflect typical Capital Region projects and are for planning only. Every Sundog quote is written, itemized, and free.
Frequently asked questions
What is the most secure type of window glass?
Laminated glass, which is two panes bonded to a tough plastic interlayer. When struck it cracks but holds together, so the opening does not clear. It turns a two second smash-and-reach into a sustained and noisy effort, which is usually enough to end the attempt.
Is tempered glass more secure than regular glass?
No, and this is a common misunderstanding. Tempered glass is safety glass in the sense that it breaks into small dull fragments rather than sharp shards, protecting people from injury. It shatters completely when it fails, clearing the whole opening in one impact, which is worse for security than glass that breaks into pieces still held in the frame.
How do I secure a sliding window or patio door?
Anti-lift blocks in the head track and an auxiliary pin lock through both panels. Together they cost under seventy dollars and close the most commonly exploited entry method, which is lifting the panel out of its track with the latch still engaged. Both install in minutes.
Does window security film work?
It helps, with one important condition: the film must be mechanically attached to the frame, not just applied to the glass. Surface-applied film peels away from the frame under impact and comes out as a sheet with the glass, which still clears the opening. Edge-anchored or wet-glazed film performs considerably better.
Should I put bars on my basement windows?
Consider very carefully, because bars over a bedroom egress window are a serious safety problem and are restricted by code. If the basement has a sleeping room, any covering over the egress window must be openable from the inside without keys, tools or special knowledge. Glass block with a vent is usually a better answer for security on a non-egress basement opening.
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