The short answer
Doors are simplest within the flap's stated thickness. Glass needs a glass-rated flap (Cat Mate 210 fits glazing up to 1 1/4 in) and usually a glazier. Walls need tunnels or extenders. Renters can use window inserts that fit without cutting.
By surface
| Surface | Example |
|---|---|
| Door | Flap within its thickness limit |
| Glass | Cat Mate 210; SureFlap with mounting adaptor |
| Wall | ClawJaw steel wall door (3.9–7.9 in); SureFlap Pet Door extender |
| Sliding window | Aluminum window insert for 32–36 in windows |
| Interior door | No-flap pass-throughs like The Kitty Pass |
Safety
SafetyCheck for wiring, pipes and studs before cutting a wall, and have glass cut by a glazier.
- Exterior doors: choose selective flaps if neighbors' cats or wildlife are a problem.
Accessories
- SureFlap mounting adaptor for glass and walls (cat flap size).
- SureFlap tunnel extender adds 2 in to the Pet Door.
Products mentioned
Questions readers ask
Can I put a cat flap in a glass door?
Yes, with a glass-rated flap; have the glass cut by a glazier.
What about renting?
A window insert that fits without cutting avoids damage.