Window box catio
A small framed box outside a window: one cat, a sunny shelf and fresh air for the cost of a few boards and a length of mesh. It is the easiest catio to fit — and the easiest to get wrong at the window.
When it fits
- Apartments and rentals where a ground-level catio is not possible (with permission)
- A first catio to see whether your cat enjoys being outside
- Ground-floor or low windows you can reach to clean and inspect
What to get right
- The window opening is the catio’s door. Seal the gaps around the frame; a cat will find a 2 in gap.
- Brackets and fixings carry the box, the cat and snow. Fix into the wall structure, not trim. Upper-storey boxes are flagged for professional review.
- Shade and a lid. A clear lid keeps rain out but can get hot in full sun; a partial or tinted cover helps.
- Window screens are not cat-proof barriers. The mesh box is.
- Egress windows — bedroom windows that are emergency exits — should not be blocked.
Plan
Front elevation
In the planner: Window box
| Starts at | 3 ft × 1 ft 6 in × 2 ft 6 in high |
|---|---|
| Depth | 1 ft – 2 ft 11 in |
| Height above ground | 0 in – 9 ft 10 in |
| Height | 1 ft 4 in – 3 ft 11 in |
| Front height | 1 ft 4 in – 3 ft 11 in |
| Width | 1 ft 8 in – 5 ft 11 in |
Sizes outside these limits fall back to concept-only.
In the beta
- Window box template with brackets and lid
- Window opening as the access point
- Elevated-installation review flag
Questions
How big should a window box catio be?
Large enough for the cat to turn around, lie down and sit up comfortably — often around 3 ft wide and 2 ft deep and tall. The template starts there and you can resize it to the window.
Can I build one on a second-floor window?
The planner treats elevated installations as needing professional review before it issues a build package, because the bracket and wall fixing carry real loads above people.
Related
Design your catio in your browser
Free to design and check. Fit a catio to your wall, window and yard, run the safety checks, and see the materials list before you buy a single board.