Cat Doors NZ: Types, Sizing, Microchip Flaps & Renting Guide

A cat door sounds simple until you are in the hardware aisle choosing between a $25 flap and a $250 one, and wondering whether cutting a hole in a rented weatherboard house will cost you your bond. This guide covers the main types, how to size a flap to your cat, why microchip doors suit New Zealand's mostly-chipped cats, and the renting and wildlife realities that matter here.

The quick answer

Measure your cat before you buy, match the door type to how much control you want over who comes in, and check what you are allowed to cut into. For most NZ homes, a microchip cat door is the best all-rounder: it reads your cat's existing chip, needs no collar, and keeps the neighbourhood toms out. If you rent, get your landlord's written consent first — cutting a hole is rarely a "minor change" you can do on your own.

Types of cat doors

Magnetic and collar-tag doors only work while the cat wears the collar, so a lost breakaway collar means a locked-out cat. Microchip doors avoid that by reading a chip your cat can never drop.

Getting the size right

Sizing is where most cat-door regret comes from. You are matching two things: the flap opening (can your cat fit through?) and the mounting height (can your cat step through comfortably?).

• Width — measure the widest part of your cat, usually the chest or hips, and add a couple of centimetres of clearance.
• Step-over height — set the flap so its bottom edge sits at roughly your cat's belly height, so they step through rather than clamber.
• Big cats — Maine Coons, large Ragdolls and chunky moggies often need a "large cat" flap, not a standard one.

A flap set too high or exiting into an exposed spot can put cats off using it, so position it at a natural stepping height and, ideally, where the outside landing feels sheltered rather than out in the open.

Microchip cat doors and your NZ cat's chip

Microchip doors suit New Zealand because so many cats here are already chipped. The implant is a passive RFID transponder built to the ISO 11784/11785 standard — a 15-digit FDX-B code at 134.2 kHz, per the WSAVA microchip identification guidelines — and that is the same standard a microchip door scans, so your cat's existing chip usually just works. It is the chip already registered on the New Zealand Companion Animal Register (NZCAR).

Why owners choose them:

• No collar needed — good for cats who slip or lose breakaway collars.
• Keeps strangers out — the flap stays locked to any chip you have not programmed in, so the neighbour's tom cannot barge in, eat the food, or spray. That matters for welfare: the AAFP/ISFM feline environmental needs guidelines describe a cat's comfort with its environment as intrinsically linked to its physical health and emotional wellbeing, and being ambushed at home by an intruder cat undermines both.
• Multi-cat friendly — most models store many chip numbers.
• Night curfews — many lock on a timer or from an app.

The limits: a determined intruder can occasionally "tailgate" in behind your cat, batteries eventually die, and a few very old non-ISO chips may not be readable — check the model's compatibility list before buying. For the NZ side of chips and registration, see Microchipping Your Pet in NZ.

Where can you fit one — and who should cut the hole

• Timber or uPVC doors — the straightforward DIY case: paper template, starter holes, jigsaw, screw the frame halves together.
• Aluminium-joinery glass doors and windows — you cannot cut tempered glass yourself; a glazier fits a matching pane with a pre-cut hole. Common in newer NZ builds.
• Weatherboard or brick walls — needs a tunnel/extension kit and a builder's eye: never cut a wall without knowing what wiring, plumbing or bracing sits behind it.
• Screen and ranchslider doors — pet-panel inserts exist; check the fit before buying.

Whatever the surface, seal well — NZ's wind-driven rain finds every gap, and a poorly fitted flap becomes a draught and a leak.

Renting? Get written consent first

This is the big one for the many Kiwis who rent. Under the Residential Tenancies Act, Tenancy Services is clear that tenants must get the landlord's consent before making changes, and must return the property to substantially the same condition it was in before. Landlords cannot unreasonably refuse a genuinely minor change and must respond in writing within 21 days — but cutting a permanent hole in a door, wall or glass pane is usually not minor, because it is hard to reverse and carries real damage risk.

Practical path for renters:

• Ask in writing and get the "yes" in writing before any tool comes out.
• Offer a reversible option: fit the flap into a replacement door or glass pane you buy and store the original, then swap it back when you leave.
• Consider non-permanent alternatives — window-insert panels or a spare interior door you own.
• Keep receipts and photos so your bond is protected at the end of the tenancy.

For the wider picture on pets, bonds and landlord approval, read Renting With Pets NZ.

Helping your cat learn to use it

Not every cat takes to a flap straight away, and forcing them backfires. Prop it fully open at first, lure them through with a treat, and reward every pass; let them get used to the latch click on electronic doors. Confident cats learn in an afternoon, nervous ones need a week of short, calm sessions. If your cat refuses, recheck the height and how exposed the outside exit feels.

Safety and welfare: the honest bits

A cat door is free-access by default, and free access is a bigger decision in Aotearoa than the hardware suggests. An unrestricted flap means roads, cat fights, disease and — importantly here — predation of native birds and lizards. International Cat Care treats safe, managed outdoor access as the goal, not unlimited roaming.

Sensible middle grounds:

• Use the 4-way lock or a timer to keep your cat in overnight, when road and wildlife risk peaks.
• Check whether your area has expectations around night containment — see Cat Curfew Rules in NZ.
• If you decide your cat is better off inside, a door is not compulsory; build a rich indoor life instead, covered in Indoor vs Outdoor Cat in NZ.

Key takeaways

• Measure your cat first: flap opening for width, mounting height at belly level.
• Microchip doors are the best all-rounder for NZ's mostly-chipped cats — no collar, selective entry.
• Microchip doors read the standard ISO 15-digit chip, but check compatibility for very old chips and expect to replace batteries.
• Glass and brick installs need a glazier or builder, not a jigsaw.
• Renting means written landlord consent and a reversible plan — a hole is rarely a "minor change".
• Free access carries road and native-wildlife risk; use night locks or curfews.

Related reading

• Microchipping Your Pet in NZ
• Renting With Pets NZ
• Cat Curfew Rules in NZ
• Indoor vs Outdoor Cat in NZ

Sources

• WSAVA: Microchip Identification Guidelines (ISO 11784/11785, 15-digit FDX-B standard), checked 2026-07-12. https://wsava.org/global-guidelines/microchip-identification-guidelines/
• Ellis SLH, Rodan I, Carney HC, et al. AAFP and ISFM Feline Environmental Needs Guidelines. J Feline Med Surg. 2013 (PubMed abstract), checked 2026-07-12. https://pubmed.ncbi.nlm.nih.gov/23422366/
• International Cat Care: Should I keep my cat indoors or allow outdoor access?, checked 2026-07-12. https://icatcare.org/articles/should-i-keep-my-cat-indoors-or-allow-outdoor-access
• Tenancy Services New Zealand: Tenants making changes to the property, checked 2026-07-12. https://www.tenancy.govt.nz/maintenance-and-inspections/regular-maintenance/tenants-making-changes-to-the-property/
• Companion Animals New Zealand: NZ Companion Animal Register (NZCAR), checked 2026-07-12. https://www.companionanimals.nz/animal-register