V · Protection
Home Hardening
analysistraining
Doors, locks, lighting, cameras, design.
Last reviewed 2026-10-07
How They Get In
55.7%
Forcible entry
Doors forced, locks broken, windows smashed. The majority, and the reason the door as a system matters more than the lock as a product.
37.8%
Unlawful entry, no force
An unlocked door or window. Over a third of burglaries required nothing but an opening, which makes the free intervention the largest one available.
6.5%
Attempted forcible entry
Tried and failed. Hardening turns forcible entries into this category.
FBI Uniform Crime Report figures for 2019. The 55.7, 37.8, and 6.5% split covers all burglaries of structures, not homes only. A structure, in the UCR definition, includes a house and also an office, barn, or similar building. Note what the data does not contain: “forcible entry” is a broad category and national crime statistics do not separately count lock picking or bump keys. The security world commonly asserts these are rare in real burglaries. That is consistent with brute force dominating.
What the Deterrence Research Found
Alarms, and Who Paid for the Research
Qualified
Interviews with 422 incarcerated burglars found 83% would try to determine whether an alarm was present, and of those who found one, about half would abandon the attempt entirely, and a further third would sometimes retreat. A separate study of 5 years of Newark police data found burglaries declined as registered alarms increased.
Both studies were funded by the alarm industry’s own research foundation. They are real university work, not marketing, but they are not independent of one another and no comparably rigorous independently funded study was found. Weigh accordingly.
Cameras in Public Areas — the Effect Is Real and Narrow
Supported
The 2019 review by Piza, Welsh, Farrington and Thomas found a significant but modest decrease in crime overall, largest in parking lots, also significant in residential areas, and larger where cameras were actively monitored. The 2008 Welsh and Farrington review covers 44 evaluations.
The effect is modest and uneven. That is not a deterrence figure for a doorbell.
Doorbell Cameras — the Claim Outruns the Evidence
Unsupported
No systematic review comparable to the public CCTV work exists for consumer doorbell cameras. A manufacturer’s claimed 55% burglary reduction in a Los Angeles pilot has not been independently verified; the police department’s own analysis found a smaller effect and area burglary later rose. An independent look in West Valley City, Utah found homes without the devices were no worse off.
A criminologist’s summary of the state of it: the evidence is insufficient to establish any reduction in domestic burglaries, let alone the figures claimed. On whether footage improves clearance rates, no rigorous published research was found either way. Buy one for the package theft and the record, not for a deterrence figure nobody has demonstrated.
Lighting Works — but Probably Not for the Reason You Think
Supported
The systematic review on improved street lighting found a statistically significant reduction in crime. Then it tested why, by comparing daytime and nighttime effects. If lighting worked by letting people see threats, night crime should have fallen more than day crime.
It did not. Crime fell in daylight too, which points away from visibility and toward the other explanation — that lighting signals investment in a place, and raises the informal social control and use of the street that follow from that. The implication is uncomfortable for the floodlight industry: a well-lit, cared-for, used street is doing the work, not the lumens.
Does Hardening Just Move Crime to the Neighbors?
Supported
A review of 102 situational crime prevention evaluations found displacement occurred in about 26% of the instances where it was examined — and diffusion of benefits, where nearby unprotected places also got safer, occurred in about 27%.
So the fear is real, but so is its opposite, at about the same rate, and most of the time neither appeared. Hardening your home is at least as likely to help the house next door as to hurt it.
The Door Is a System
The Jamb, Not the Lock
A deadbolt is only as good as what its bolt lands in. The common residential failure is the door frame splitting or the strike plate tearing out, not the cylinder being defeated. Long screws into the structural framing behind the jamb, and a reinforced strike, cost very little.
Consistent with forced entry dominating the statistics, and consistent with what every locksmith says — but stated here as engineering reasoning. No independent laboratory study is cited.
What a Lock Grade Actually Certifies
Look for the BHMA Certified label. Residential locks are rated A, B or C for security, durability and finish.
UL 437 is the separate standard specifically for resistance to picking, drilling and manipulation. If covert attack is the concern, that is the mark to look for, not the ANSI grade.
Glass Beside a Lock Is a Lock with a Doorbell
A deadbolt next to a sidelight or a glass panel can be reached through. Laminated glazing, a double-cylinder arrangement where local fire code permits it, or security film change the calculation.
Check fire egress rules before installing anything that requires a key to exit. A door you cannot get out of in a fire is a worse hazard than the one you were solving.
The Free Intervention
Over a third of burglaries involved no force at all. Locking doors and windows, including on the second floor and the garage service door, outperforms any purchase on this page and costs nothing.
This is the single highest-value line in the wing, and it has no product attached to it.
Design, Not Gadgets
Natural Surveillance
Arrange sightlines so that normal activity is visible — windows overlooking approaches, trimmed shrubs below sill height, lighting at entries. The aim is that ordinary people going about ordinary business can see, not that a camera can.
Natural Access Control
Guide movement with paths, planting, gates and grade changes so that legitimate routes are obvious and other routes take deliberate effort.
Territorial Reinforcement
Mark where private space begins — surface changes, low fencing, planting, maintenance. The signal is that this ground is claimed and attended to.
Maintenance
Repair quickly. Visible neglect reads as absent guardianship, which is the same signal the lighting research seems to be detecting.
Activity Support
Put legitimate use into a space. Places used by people for ordinary reasons are harder to use for other reasons.
Crime prevention through environmental design traces to C. Ray Jeffery’s 1971 book and Oscar Newman’s defensible space work in 1972. The evidence deserves an honest sentence: no systematic review of CPTED as a single integrated program was found. Its components have separate evidence bases of varying strength — lighting and public-area cameras have systematic reviews, as covered above. Defensible space theory itself has mixed empirical support, and was challenged early and directly by fieldwork finding that social factors mattered more than the physical design prescriptions. Use CPTED as a useful way to organize attention, not as a validated program.
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