Guardian Angel DIY › Guides › How to Secure Windows: 6 Low-Cost Fixes That Work

How to Secure Windows: 6 Low-Cost Fixes That Work

By Guardian Angel DIY · Updated October 27, 2026 · 10 min read

Disclosure: This guide contains affiliate links. If you buy through them, we may earn a commission at no extra cost to you. As an Amazon Associate, Guardian Angel DIY earns from qualifying purchases.

A window lock looks like a lock, but on many homes it is little more than a latch that keeps a window from rattling. A thin tool slipped between the sashes can flip it open, and a lock does nothing about the glass itself. The good news is that windows are one of the cheapest openings to improve. Most fixes cost between $6 and $15 per window, and most need no special skill. This guide walks through six, in the order we suggest doing them, and shows how to do each one without trapping your family in a fire.

Why windows are a weak point

Windows fail in three ways, and each one has a different fix.

• The latch is easy to defeat. On many double-hung windows, the lock is a small cam that turns to pull two sashes together. On older ones, a thin blade or putty knife slipped through the gap can nudge it open from outside.
• The window can be lifted or slid. If the latch fails or was never locked, the window simply opens. An unlatched window is by far the most common way in.
• The glass can be broken. Breaking glass is noisy and risky for the intruder, so it is less common than opening a window, but it happens, and it is more likely on a secluded side of the house.

A window is also an opening you may want to keep cracked for fresh air, which is why a fix that blocks the window shut is not always the right one. The six fixes below let you choose between a fully secured window and a vented one.

Check your windows first (15 minutes)

1. Walk the outside. List every window within reach of the ground, a deck, a porch roof, a garage roof or a sturdy tree. Include basement windows and windows hidden behind shrubs.
2. Test every latch. Lock each window and try to lift the lower sash. Push on a sliding window. A window that moves, rattles or has a loose latch is a priority.
3. Look at the latch type. A basic cam latch that can be reached through a gap between the sashes is the weak kind. Look for a tight, even gap.
4. Check the frame. Look for rot, cracks and loose screws. Screws that spin in soft wood hold nothing.
5. Look in from outside at night. With the lights on inside, what can a passer-by see? Electronics, jewelry and open rooms draw attention.

Fix 1: Replace weak latches ($6 to $8 per window)

This is the first thing to do on any window with a loose, worn or old latch. A modern sash lock has a cam action and alignment lugs, and it is designed so that a thin tool cannot slip between the sashes and flip it open. A good lock is made of die-cast metal, includes its own screws, and installs in minutes with a screwdriver.

How to do it

1. Close the window and unscrew the old latch, taking note of where it sits.
2. Fit the new latch in the same location, centered on the meeting rail so the two halves line up.
3. Use the screws that come with it, and drive them in until the lock is firm but not so tight that it bends the frame.
4. Test it by closing and locking the window, then pushing and lifting on the sash.

You need one lock per window, and many windows have two. Do the ground floor first.

Fix 2: Add a pin or stop ($6 to $9 for a box)

A pin is the old-fashioned backup, and it works. It is a nail or bolt that passes through the lower sash into the upper one, so even if the latch is defeated, the window cannot be raised past the pin.

How to do it

1. With the window closed, drill a small hole at a slight downward angle through the top corner of the lower sash and part way into the upper sash. Use a bit slightly larger than the nail.
2. Insert a nail or a bolt into the hole. A 16-penny nail works.
3. To open the window, pull the pin. To lock it again, push it back in.

Two cautions. First, drilling through the sash is permanent, so go slowly on older wood and test on a hidden spot. Second, a pin only helps if it is in the hole, and it must be easy to remove by hand. Tie a short loop of string through a nail head, or use a small eye bolt, so anyone can pull it in seconds.

Fix 3: Lock sliding windows ($10 to $13 for four)

Horizontal and vertical sliding windows have their own weaknesses, and the factory latch is often worn or missing. A clamp-on or add-on sliding window lock fits on the track or frame and stops the window from opening, or limits how far it can open. Many install without drilling. Fit varies by frame profile, so measure before you buy.

Fix 4: Let in fresh air safely ($10 to $14 for four)

Many people leave windows open a few inches, which is exactly when a window is most at risk. A wedge or flip lock keeps a window from opening past a set gap, so you can have airflow without a person-sized opening. A simple hook-and-loop wedge needs no tools or screws, and it releases by hand in seconds, which makes it a good choice for bedrooms. It limits the opening rather than locking the window shut, so pair it with a latch on windows you want fully secured.

Fix 5: Strengthen the glass ($65 to $75 per roll)

Security film is a clear, tough layer applied to the inside of the glass. It does not make glass unbreakable, and the glass can still crack. What it does is hold the broken pieces together, so an intruder cannot easily clear an opening. That slows entry, makes more noise and increases risk for the person trying it. It also adds some resistance to accidental breakage and blocks ultraviolet light.

Film is the most useful on windows within easy reach of the ground, on glass beside a door, and on any window on a hidden side of the house. It is not worth covering every window in the house, since the cost climbs quickly. One roll covers roughly one large window or several smaller ones.

Tips for applying film

• Clean the glass thoroughly, because any dirt will show as bubbles.
• Use the application solution and a squeegee, and work from the center out.
• Trim the edges carefully. Edge lift and bubbles are the most common mistakes, so take your time.
• Allow it to cure, which can take days.

Fix 6: Limit the view and add an alert ($13 to $25)

• Use curtains or blinds at night. Window coverings stop strangers from looking in at valuables or checking whether anyone is home. Use sheer coverings by day, since closed curtains all day can look odd.
• Keep valuables away from windows. Laptops, cameras and jewelry in view invite attention.
• Trim shrubs below the sill. Plants that hide a window also hide someone working at it.
• Add a chime. A battery-powered door and window sensor makes a loud sound when a window opens. A multi-pack covers several openings for about $15. See our guide to alarms with no monthly fee.

Keep every bedroom window a safe exit

In a fire, windows can be the only way out. Building codes in most places require sleeping rooms to have an opening that can be used for escape, and that opening must work without a key, a tool or special knowledge. Follow these rules:

• Never screw or nail a bedroom window shut. A permanent block removes an exit.
• Use removable devices. Pins, wedges and latches that release by hand are fine. Anything that needs a key is not.
• Practice. Have every household member, including children, open each bedroom window in the dark.
• Be careful with bars. Window bars on sleeping rooms need a quick-release from inside, and may be restricted by local code. Check before you buy.

What it costs: a simple plan

Common mistakes to avoid

• Trusting the latch alone. It is the weakest part of the window.
• Leaving windows unlocked "just for a minute." An unlocked window is the most common way in.
• Blocking an exit. Never use a lock a family member cannot open fast in an emergency.
• Forgetting the hidden windows. Back, side and basement windows matter more than the front. Our guide on basement windows and window wells covers those.
• Skipping the doors. A locked window beside a weak door only moves the target. See how to reinforce a front door.
• Using bars without a release. They can trap people in a fire.

If you rent

Wedge locks, clamp-on sliding window locks, curtains and chimes need no changes to the property. Latches and pins involve small modifications, so ask your landlord. If a latch is broken, the frame is rotted or a window will not lock, report it as a maintenance request in writing.

Frequently asked questions