Window Security

Pick in 10 seconds

• If the window slides sideways → a sliding window lock on the track, or the $7.99 no-drill window door lock on the frame rail.
• If it lifts up and down → the window sash lock (no drilling), or the keyed window lock when you want a key in the loop.
• If it swings on hinges (casement, crank, tilt-turn) → the keyed sash jammer.
• If you want it open for air → the window restrictor, which stops it at about four inches. Keep it off a window that is a bedroom's only way out.
• If it is the glass that worries you → security film holds a broken pane in its frame.
• If you want noise before anyone is inside → the TremShield vibration alarm on the glass. Six are $99, $16.50 each.

Why the window latch is the weak spot

A window latch keeps a window shut against wind, not against force. You rarely need bars or new glass: stop the sash moving, hold the glass together, and make noise the moment the pane is touched.

Sliders: stop the slide, then think about the lift

The sliding window lock clamps to the track with a thumb-screw and stops the panel where you choose, shut or at a vent gap. The no-drill window door lock does the same job on the frame rail with a hand-tightened clamp. Neither one stops a panel being lifted out of its track. If there is clearance above the panel, two screws driven into the top channel take that room away for pennies. More fixes, cheapest first, are in what to do when a window won't lock.

Hung windows: pin the sash

The sash lock tightens onto the frame by hand, no drilling, and pins the sash shut or at a vent gap, even when the window's own latch is broken. Two come in a pack. The keyed window lock screws on where the two frames meet: a thumb-turn can be flipped by a hand reaching through broken glass, a key lock cannot. Both locks in its pack open with the same key.

Hinged windows and French door leaves

Casement, crank and tilt-turn windows give track devices nothing to grip. The sash jammer takes two screws in the frame beside the sash, and its arm swings over the sash edge, so the window cannot be pushed open even with the handle turned. Two come in a pack: two windows, or one for each leaf of a pair of French doors. The full match-up is in which window lock fits which window.

Air at night without a wide gap

The restrictor's steel cable lets a window open to about four inches, then stops it, and its key releases it fully for cleaning. It is not a child-safety device. Because it takes a key, keep it, and the other keyed locks, off any window someone might need to escape through. More in how to sleep with the window open safely.

The glass, and the alarm on it

Security film lets a pane crack but keeps the shards stuck in place, so the pane cannot be quickly cleared and reached through. What each glass type can take is in are there burglar-proof windows.

The TremShield alarm is a thin disc that sticks to the pane and sounds at 125 dB when the glass is struck or pried, while the person is still outside. It needs no Wi-Fi or app, costs nothing monthly, and a sensitivity dial tunes out trucks and wind. Spare mounting pads let you move one, and warning decals announce it from the walkway.

Where to start, and how many

Walk outside and count the panes someone could reach from the ground: ground-floor windows, basement windows, anything beside a fence line or a low roof. Each gets a lock that fits its type and an alarm on the glass. Renters: the clamp-on locks and the alarm come off clean; the keyed lock, the restrictor and the sash jammer screw in, so ask first (see the renter-friendly security guide). Patio doors are in Door Security, and the 60-second alarm finder places each alarm. At six, take the pack: six TremShield alarms are $99, $16.50 each, with 2 free no-drill window locks.