Fitting a pet door to a security screen door

Yes, usually, but the mesh decides how

Petway says its security screen pet door suits all types of security screens, and the infill inside the frame decides how the fitting is done. Petway, an Australian pet door maker, publishes one set of fitting instructions for diamond grill doors and another for stainless steel mesh doors.

On a diamond grill door, Petway's method cuts a section out of the grille with bolt cutters or a hacksaw. The insect screening behind the grille gets peeled back first, then trimmed around the new frame and splined into the pet door's own channel. That's the method for a Diamond Grille door, where fibreglass sits behind the grille to keep insects out.

Petway includes a spacer for fitting into stainless steel mesh doors. Whichever infill you have, the opening is a permanent cut. A cut grille or mesh can't be uncut, so decide before anything gets cut.

Retrofit or build it into a new door: same trade-off either way

Fitting a pet door to the screen you've got and ordering a new door with one both end in the same place: a security door with an opening in its infill. The NSSA's position covers any pet door installed within a security door, so the timing doesn't change the result.

Retrofitting is the simpler path. Petway says its security screen pet door can be fitted without taking the door down, and Cairns Security Doors fits pet doors into existing screens as part of its onsite repair work. If the screen is otherwise in good shape, adding a flap doesn't call for a new door.

A new door makes more sense when the old one is due for replacing anyway, or when you'd rather put the pet's access somewhere else. One option is to leave the front security door uncut and fit the flap to a flyscreen door at the back. Hinged or sliding doesn't rule a pet door out, either. Petway says its slim frame lets a sliding door slide past without catching.

Size the opening to the pet, then check the door

Size the pet door to the animal first, then check the door has room for it. Petway's size guide starts with height, measured from the top of the pet's back down to the upper ankle. Pets crouch a little going through a flap, with the head dropping and the feet lifting, so the flap doesn't need to clear full standing height. Width comes from the widest point, usually the chest or hips, plus a bit of clearance so your pet isn't squeezing through.

Before anyone cuts, Petway suggests cutting the hole size out of cardboard, holding it in the doorway and calling your pet through. A cut in the infill can't be undone, so the cardboard test is worth doing first.

Watch the gap between flap size and cut-out size, too. Petway's medium flap opening is 305 mm high, yet the hole cut into the infill is 375 mm high by 285 mm wide, because the frame needs room around the flap. A bigger dog means a bigger hole in the screen, and the table below shows how fast that grows.

What a pet door does to security: the door loses its compliance

A pet door weakens a security door at the opening, and the industry body treats that as the end of the door's compliance. The NSSA's buying guide says that once a pet door is installed within a security door, the door is no longer compliant with Australian Standards, as the opening compromises the security of the door. The guide makes no exception for size or brand.

The flap's own locks are there to manage the pet. Petway's small and medium security screen pet doors have sliding lock clips below the flap to keep a pet in or out, and Petway says those clips are designed for light to moderate force. The large door uses a lock-out panel that slots into the back of the frame.

So a pet door in a security screen is a trade, plain and simple. You get a dog or cat that lets itself in and out. In the NSSA's view, the door at that doorway can no longer be called compliant with Australian Standards. If that door has to stay uncut, the options in the last section keep the pet's access away from it.

Keeping insects and weather out

On a diamond grill door, Petway's instructions run the insect screen into a spline channel on the pet door frame, so the screening is locked into the frame instead of left as a loose cut edge.

The flap has a magnet in it to stop it moving about. Petway also says the pet door is UV stabilised, which is worth checking for on any door that cops afternoon sun.

For hot or cool weather, the screen isn't the only layer. Petway says its pet door allows you to close a glass door behind it, and that a security screen pet door can be lined up with a timber pet door of the same size. Line the two up and the solid door behind gets its own flap. The main door can then stay shut on a hot day while the dog still gets in and out.

If the security door has to stay uncut

If you want the security door left uncut, give the pet a different way through. The NSSA's position only bites on the door that gets the opening, so the fix is choosing which doorway takes the flap.

That way the front security door stays uncut, while another door handles the pet traffic. Here are two straightforward ways to set that up.

• A pet door in a flyscreen door. Petway's model fits a standard insect screen door using a support L bracket, so a back or side flyscreen can take the flap while the main security door stays whole.
• Pet mesh on a busy screen. Pet mesh is fibreglass made thicker and stronger than the standard screen, so a dog pushing against it is less likely to rip it. Pet mesh is an insect screen, so it adds no security, and the range of mesh page sets it against the stainless and perforated options.