Window security bars or security screens: how they compare

Bars, grilles and security screens are three different things

A window bar is a set of fixed metal bars over or across a window, there to stop a person climbing through. A grille is a patterned panel, often steel or aluminium, that does the same job with a decorative look. A security screen is a framed screen that has been tested and labelled as a security product.

The lines between them blur, which is why the label matters. The National Security Screen Association (NSSA) lists steel decorative or grille infills and aluminium grille among the infills a security door can use, alongside perforated aluminium and stainless steel mesh. So a grille can be the security layer of a tested screen. A grille or set of bars sold on its own, with no compliance label, hasn't been shown to meet that standard.

The Australian Standard covering this is AS 5039.1:2023, titled Security door and window screens. Its scope covers windows as well as doors. That's the yardstick worth using whenever someone quotes you bars, a grille or a screen for a window.

Do window bars deter burglars? Yes, and so do locked security screens

Window bars do put burglars off, and so do security screens. In a study by the Australian Institute of Criminology (AIC), burglars noted alarms and grilled windows and doors as an effective deterrent. When the same group described effective security, they listed switched on alarms, security screens, roller shutters and dogs. The researchers concluded that the harder a house is to get into, and the longer it takes, the more it deters active burglars.

The study doesn't rank bars against screens, and no Australian source we found does. What it does show is where bars sit among other measures. Asked what would typically put them off, burglars named grilled windows fifth, behind dogs, alarms and lighting:

• A dog: 61.4%.
• A working alarm system: 49.1%.
• Sensor lights: 22.8%.
• Lights on inside the house: 19.3%.
• Grilled windows or doors: 19%.

How burglars get in through windows: mostly unlocked, mostly fast

Most burglars in the AIC study said they didn't need to force anything. Two-thirds of the burglars (66.2%) said they usually got in through unlocked doors or windows, and the rest broke a door or window. Three-quarters were inside in under five minutes. Asked about homeowners' most common mistake, they said it was leaving doors or windows unlocked or open.

Queensland Police say the same thing in plain terms: many house break-ins are crimes of opportunity, with entry through an open or unlocked door or window. Their advice is to fit window locks that meet Australian standards and never leave the keys in them.

That changes the question. Fixed bars block a window whether it's open or shut, which is their strength. A security screen blocks the window only when it's closed and locked, but it lets you keep the glass open behind it. In a Cairns summer, being able to leave the glass open is often the deciding point.

Testing: the label is what separates a security screen from a bar

The quickest way to tell a tested product from an untested one is the compliance label. The NSSA says its members must label every security screen product that meets AS 5039, and it puts the rule bluntly: if it isn't labelled, it isn't a security door. It describes a security screen as a physical barrier that lets air through while keeping insects and intruders out, and says it must pass strict testing to that standard.

The tests are specific. Screens installed to the installation standard are designed to withstand knife shear, jemmy, probe, corrosion, pull and impact tests. SCREENGUARD, the stainless mesh we make screens with, states its screens pass dynamic impact, knife shear, anti-jemmy, pull and probe testing.

For bars, ask the supplier what they've been tested to and ask to see the evidence. If the answer is a look rather than a label, you're buying a deterrent, not a tested security product. Fitting matters too: the NSSA says installation is just as important as the product, and strongly advises against doing it yourself.

Insects, view and breeze: bars need a second layer

Bars and open grilles are spaced to stop a person, so on their own they don't keep mosquitoes or sandflies out. Pair bars with a separate flyscreen and you have two things to maintain and look through. Our Diamond Grille and Colonial Casting screens deal with this by fitting fibreglass mesh behind the grille or cast panel as standard: the grille does the security work, and the fibreglass keeps the insects out.

A woven or perforated security mesh does both jobs in one layer. That's the main reason people in the tropics choose one, since the NSSA describes a security screen as letting air through while keeping insects and intruders out.

View is personal. Bars and grilles put a pattern across the window. Woven stainless is a fine weave you look through, and our perforated aluminium gives about 40 percent view through, so it reads darker. Stand in front of a sample of each in daylight before you choose. Our range of mesh page compares the five meshes we fit, and the diamond grille vs stainless steel mesh guide goes deeper on a grille against a fine weave.

Keeping a way out of bedrooms: bars and grilles need to open from inside

Any bar, grille or screen on a bedroom window should open quickly from the inside. The Queensland Fire Department says doors or windows with security bars should have quick-release devices, so they can be opened from inside in a fire. Its escape plan sheet says to try for two ways out of every room, with a window as the last resort when the doors are blocked.

Fixed bars that can only come off with tools fail that test. This is the point to check before anything is made, not after. The fire department's advice for doors and windows is:

• When installing security grilles on windows, choose a type that opens outwards easily from the inside.
• Install deadlocks that open from the inside without a key.
• If a key is needed, keep it in a safe spot near the door or window, out of reach of intruders.
• Cut down the number of keys by having locks keyed alike.

Cyclones and salt air: neither one is debris protection by default

Neither bars nor an ordinary security screen should be counted on to protect glass in a cyclone. Queensland's cyclone building guidance, from the Queensland Reconstruction Authority, says debris screens are different from sun screens and security screens, and that effective debris screens are rated by testing for their resistance to debris. A permanently fixed debris screen may double as a security screen, but only a product that holds the debris rating can claim that. Our guide on security screens and cyclone protection covers what to ask for.

Salt air is the other Cairns test. The NSSA tells coastal buyers to consider corrosion resistance, and says marine grade 316 stainless mesh is designed to prevent rust. SCREENGUARD, the mesh we use, is 316 marine grade. For bars or a grille, ask what metal and coating they're made from and what coastal care the maker asks for, and get that in writing before you buy.

Which suits which window, and what to use instead of bars

Choose by what the window needs to do. If you want it open for air, a locked security screen covers both breeze and security. If you like a patterned look, a grille screen gives you that pattern with insect mesh behind it. Fixed bars without a quick release suit only windows nobody will ever need to climb out of. Every screen we make is made to measure and manufactured in Cairns, so each window can be priced on its own terms.

• A bedroom window: a hinged or openable screen with a quick release, never fixed bars. Our range of mesh page answers which mesh suits a window you may need to climb out of.
• A living room window you open for the breeze: woven stainless mesh, so the view stays clear and the insects stay out.
• A window facing the footpath or a neighbour: perforated aluminium for privacy, or a grille paired with one way vision mesh.
• A character home where the look matters: a decorative grille or cast panel screen. Our heritage and decorative security doors guide shows the patterns.
• Any window you keep shut: a simpler fix may be a window lock to Australian standards, which Queensland Police recommend for every window.