Indoor cats live longer, but they still crave fresh air, sunshine, and the stimulation of watching birds. A DIY catio gives them outdoor access without the risks of traffic, predators, or wandering into a neighbor’s yard. These screened enclosures range from simple window boxes to full walk-in structures, and most cost between $150 and $600 in materials. Building one yourself cuts the price roughly in half compared to buying a prefab kit.
Types of Catios
Window Box Catio
A window box catio attaches to an existing window frame and extends 2 to 3 feet outward. It works like a bay window for cats, giving them a screened perch without taking up yard space. Dimensions are typically 3 feet wide, 2 feet deep, and 2 feet tall. Material cost runs $50 to $150 using 2×2 lumber and galvanized hardware cloth.
Patio-Attached Catio
This style leans against an exterior wall with a cat door or window access point. Standard sizes run 4 to 8 feet wide, 3 to 6 feet deep, and 6 feet tall. Cats enter through a pet door or a modified window screen. Material cost is $200 to $400 for pressure-treated lumber, hardware cloth, and roofing.
Freestanding Catio
A standalone structure placed anywhere in the yard, connected to the house by a tunnel or used as a supervised outdoor space. These can be as large as 10 by 12 feet and include shelves, climbing poles, and enclosed resting boxes. Expect to spend $400 to $800 on materials for a mid-size freestanding build.
Materials and Tools
- Frame lumber: 2×2 or 2×4 cedar or pressure-treated pine. Cedar resists rot naturally and costs about $3 to $5 per 8-foot board. Pressure-treated pine runs $2 to $4 per board
- Screening: 16-gauge galvanized hardware cloth with 0.5-inch openings. Avoid fiberglass window screen, which cats can claw through in minutes. Hardware cloth costs $30 to $60 per 100-square-foot roll
- Fasteners: Galvanized or stainless steel screws, staples, and L-brackets. Standard zinc-plated hardware will rust outdoors within a year
- Roofing: Corrugated polycarbonate panels ($15 to $25 per 8-foot sheet) or outdoor-rated shade cloth for partial coverage
- Cat door: A locking pet door sized for cats, typically 6 by 6 inches or 8 by 8 inches. Prices range from $15 to $50
Basic tools include a drill/driver, circular saw or miter saw, staple gun with 0.5-inch staples, tape measure, level, and safety glasses.
Planning and Design
Start by measuring the available space and deciding how your cat will access the catio. A window-mounted cat door is the simplest entry point if you rent and cannot modify walls. For homeowners, cutting a wall-mounted cat door with a locking flap gives you more placement flexibility.
Plan for at least 8 square feet of floor space per cat. Two cats need a minimum 4-by-4-foot enclosure, but bigger is always better. Include vertical space with shelves or ramps at 12- to 18-inch intervals so cats can climb and perch at different heights.
Check local building codes before starting. Most municipalities do not require a permit for structures under 120 square feet that are not permanently attached to the house, but setback rules may apply if the catio sits near a property line.
Building a Basic Patio-Attached Catio
- Build two identical rectangular side frames from 2×4 lumber, 6 feet tall by 4 feet deep. Connect them with horizontal top and bottom rails at the front, creating a box frame
- Anchor the back of the frame to the exterior house wall using lag screws into wall studs. Level the frame and shim if the ground slopes
- Attach hardware cloth to all open sides and the top using galvanized staples every 3 inches. Overlap edges by at least 1 inch and fold sharp wire ends inward
- Install a corrugated roof panel on top, pitched slightly away from the house for drainage. Secure with roofing screws and rubber washers
- Add interior shelves by screwing 2×2 cleats to the frame and laying plywood or cedar boards across them. Sand all edges smooth
- Install the cat door in the window or wall, following the manufacturer’s instructions. Test the locking mechanism to confirm it latches securely
Weatherproofing and Safety
Seal all lumber joints with exterior wood glue in addition to screws. Apply a coat of exterior wood stain or paint to cedar frames every 2 to 3 years, or use Thompson’s WaterSeal for a clear protective finish. Pressure-treated wood can go without finish for 3 to 5 years but will gray over time.
Inspect the hardware cloth monthly for any holes, rust spots, or loose staples. A determined cat or a visiting raccoon can exploit a gap as small as 3 inches. Reinforce any weak points with additional staples or wire ties.
Provide shade for at least half the catio floor area. Cats can overheat quickly in direct sun, especially in southern states where summer temperatures exceed 90 degrees F. A polycarbonate roof with UV filtering or a shade cloth rated for 70 percent coverage keeps the space cool enough for year-round use.
Interior Setup for Happy Cats
Shelves at varying heights are the single most important feature. Cats feel secure when they can survey their surroundings from an elevated perch. Add a hammock or padded shelf near the top for lounging and a ground-level hiding box for timid cats.
A shallow planter of cat grass or catnip gives cats safe greenery to nibble. Avoid placing toxic plants like lilies, azaleas, or sago palms anywhere near the enclosure. Hang a bird feeder just outside the catio screening for built-in entertainment, and your DIY catio will quickly become your cat’s favorite spot in the house.
