Catio materials guide — lumber, mesh, roofing and hardware

Most DIY catios are built the same way: a timber frame, welded wire mesh on the open faces, a roof of mesh or sheet, and a door. Here is what to know about each part.

Framing lumber

Sizes. Lumber is sold by nominal size; the actual size is smaller. A "2×2" is about 1½ × 1½ in, a "2×3" about 1½ × 2½ in, and a "2×4" about 1½ × 3½ in. OpenCatio3D names parts by nominal size but draws and cuts them at actual dimensions.

• 2×2 suits window boxes, tunnels and small frames.
• 2×3 is a common choice for lean-tos.
• 2×4 gives stiffer walls and longer spans for larger catios and roofs that carry sheets or snow.

Treatment. Wood in contact with soil or concrete should be rated for ground contact. Above ground, many builders prefer naturally durable or untreated wood with an exterior finish. Whatever you use, let finishes cure fully before cats move in, and avoid leaving treated-wood offcuts or sawdust where cats can chew them.

Stock lengths. Boards commonly come in 8, 10 and 12 ft lengths. Designing walls around these lengths reduces waste; the planner packs every cut onto the stock lengths you choose.

Mesh

Use welded wire, not chicken wire or plastic netting. Look at:

• Opening size — small enough for your smallest cat. 1 × 1 in and 1 × ½ in are common catio choices; large fence meshes such as 2 × 4 in let many cats through.
• Gauge — a lower gauge number means thicker wire. Heavier wire resists bending and animals better.
• Coating — galvanised after welding (GAW) generally resists corrosion better than galvanised before welding; vinyl coating is softer and less visible.

The mesh and roofing guide goes deeper.

Roofing

A catio needs a roof — cats climb. Options are mesh (cheapest, lets in rain and snow), clear or tinted polycarbonate, corrugated metal or fibre sheet, or a mix of cover and mesh. Sheets need rafters at the spacing the manufacturer specifies and a slope to drain.

Fixings and hardware

• Exterior-rated screws for the frame — galvanised, coated or stainless.
• Mesh fixings — screws with washers, or heavy-duty staples — at close, even spacing along every edge, often covered with a batten.
• Hinges and latches rated for outdoor use; a self-closing hinge or spring on human doors.
• Ledger fixings into the wall structure for attached catios — not just siding or trim.
• Ground anchors or fixings for freestanding catios.

Finishes

Stains and sealers protect wood but should be fully cured before cats use the catio. Follow the product's instructions and keep cats out while finishes dry.

Frequently asked questions

What is the best wood for a catio?

There is no single best. Use ground-contact rated lumber where wood meets soil or concrete, and a durable, finished wood above ground. Size the framing to the span and roof load.

Can I use chicken wire for a catio?

It is not recommended. Chicken wire is thin and easily bent or torn by cats and predators. Welded wire mesh is much stronger.

Do I need to paint or stain the frame?

Not strictly, but a suitable exterior finish extends the life of the wood. Let it cure fully before cats use the catio.