When I mentioned to my wife Kim that we should build the outdoor cat enclosure attached to the house she was excited to get started. I had meant something small, fast to build and utilitarian. Kim had dreams of a luxury massive cat condo filled with as many cat-friendly contents as possible. We live on a 16-acre hobby farm near Trenton, Ontario and have never been able to allow the cats to go outside due to the coyotes and busy road nearby. Having a safe outdoor space attached to the house via a cat door flap was the ideal solution.

I’m an IT computer guy who likes to get technical and plan things out. Kim is a veterinarian who’s picked up some carpentry skills whilst fixing up our farm we share with two horses, six chickens, four indoor cats, two barn cats and a Labrador who is always getting into trouble.

Kim has counseled many of her clients at the vet hospital on building cat enclosures, as indoor cats need environmental enrichment and exercise to stay physically and emotionally healthy. Destructive scratching and chewing, playing and exploring are normal cat behavior, so giving your cat an acceptable place to do this avoids ruined furniture and prevents a stressed-out cat.

A few things to keep in mind:

1. Safety – keep cats in and predators out, no sharp objects, structurally sound, lock so can’t be set free.

2. Functionality – shady areas, shelter from rain, hiding areas, easy for cats to get in and out. People can enter to maintain and clean the enclosure.

3. Building materials – smooth edges so no splinters, cedar for pleasant smell and weather resistance.

4. Curb Appeal – temporary if need to sell home, private area of unused yard, esthetically pleasing.

Get creative

I’m sure the design we came up with will differ from what you want, so rather than share specifics about the dimensions we made each piece, and the exact order of operations we took to complete this project, I will offer general dimensions, along with some guidelines and ideas about how to outfit the enclosure so your cats can have a fun and safe time using it.

First decide on an overall shape and size for the enclosure, and if you need to have the inside play area off the ground. Proximity to an appropriate window is of key concern, though a long walkway might have to be used in a pinch. At that point you can design and build the interior play area of the enclosure. Beyond the basic tips mentioned above, you’re only limited by your imagination.

The cat enclosure we built is 8′ long, 3′ wide and 9′ tall at the back wall, 8’6″ tall at the front wall. We wanted it up off the deck so the two outdoor barn cats would not harass the indoor cats too much, so we made a base to place it on, to bring it off the ground and provide solid support for not only the cats, but to support us when we’re inside it.

Start down low

Even if you don’t have outdoor cats nearby, it’s likely a good idea to keep it off the ground as that will only make it harder for wildlife to enter the enclosure and continue on into your home.

The sturdy base structure, with six 42″-long 4×4 posts is held together with 2x4s around the outside of the posts. Four 2x4s support the middle of the structure, two of them span the width (one on either side of the middle posts), and there are two lengthwise down the middle, connecting to the wood on the perimeter. Deck boards are attached to the base with deck screws.

The enclosure walls

We used 2x4s to make the basic frame and built four stud walls separately in the barn. The two long sides measured 8′ long x 9′ tall and 8′ long x 8’6″ tall. The studs are about every 19″ on center with horizontal supports every 34″ on center. We turned the wood on its side so there would be more surface area to overlap and attach wire mesh to. The two short sides fit in between the long sides to make a total width of 3′. One end is solid mesh, and the other end we framed in a door on hinges in the lower half so a person can get into the catio. The door measures 25″ x 45″, with two horizontal supports.

We made the smart choice to put the heavy gauge mesh wire onto the outsides of the walls while they were still lying on the barn floor. We used large, U-shaped fencing staples. We overlapped the mesh 2″ on the horizontal supports and placed our staples every fifth wire – roughly every 5″. This ensured that it would survive a sustained coyote attack.

We moved the walls over to the house from the barn on an ATV flatbed trailer, as they were quite heavy. With only two of us it was challenging getting them up onto the base. In hindsight, some extra help would have made it much easier.

The walls were secured to the deck through the floor plates and to each other like framing in a room.

The roof

Four 2x4s were used on their edges for the roof joists and three 2x4s were placed across them horizontally to attach the three Ondura roof panels. The roofing panel choice was because that is what we had on hand. A normal shingle job would have worked as well.

The overhang on the front is longer than the back to keep driving rain out of the enclosure a little better. The triangular gaps under the roof at either end were filled in with scrap wood to prevent cats from escaping. The top 6″ of the back wall was filled in with sections of 2×6 between the studs, so the same amount of mesh could be used on all sides.

Tunnel to the window

Pine strips, 2×2, were used to make a rectangular tunnel 10″ wide, 16″ tall and 20-1/2″ long. A 1×6 cedar board was trimmed to fit inside the tunnel for a smooth floor to walk on. We covered the tunnel with wire mesh and secured with the U fencing staples.

The window was opened and a 1×10 piece of rough cut spruce was placed in the window with the cat flap door assembled where we wanted it. A hole was cut in the metal mesh wall of the cage to allow the tunnel to enter the catio. The tunnel was screwed to the window and the spruce board to prevent it from moving.

We wired the tunnel mesh to the catio wall mesh to prevent any escape attempts. This provides the cats with a choice of when to come in and out, as well as keeping all the bugs out. On the inside of the house the cats have access to the window through a set of cat sized cedar stairs.

Climbing apparatus

Creating and making the climbing apparatus for the cats was by far the most fun. We made it up as we went along, without official plans. There are so many ways you can go with this aspect of the build, but the following is a rundown of what we built.

The hut

A medium-sized hut on a post, with a suspension bridge to a mid-way support and then a platform was where we started. A 4×4 pressure-treated post holds the rectangular 1″ thick base under the square cat hut, which sports an arch door opening on the side and a rectangular door on the front with a moon shape cut out of the back. The fourth side is solid. Three ornate wooden shelf brackets were attached to the post to hold three 12×6 pieces of the 1×6 cedar board to be used as spiral stairs by the cats to climb the post. Two pressure-treated shelf support brackets were placed under the front and back of the platform.

The hut boasts a small deck out front, which has a wooden railing made out of decorative mini baluster. The floor of the hut was attached to the post with four 3″ screws before the roof went on. A 18″-long piece of 1×6 spruce was screwed to the base of the post and then that ‘foot’ was screwed to the deck for support. The hut was still quite wobbly; two supports were attached horizontally from the cage frame to the 4×4 post, one on either side for stability.

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The roof panels were made from scrap exterior plywood, and tar paper while cedar shingles were used to finish the roof. Pieces of 1×1 material 8″ long were used to aid in attaching the roof peaks together, and to the hut walls. We first screwed the wood pieces to the top outer sides of the walls, giving us more wood to screw the material to.

Suspension bridge

The suspension bridge allows the cats to access the hut. It’s made of 1×6 cedar boards cut into 1-1/4 long strips. Running the grain lengthwise would have been stronger, but the parts have held up well. Each piece was sanded on the belt/disc sander to slightly round all edges. On the drill press we drilled 3/8″ diameter holes, 1-1/2″ in from each end, and 3/8″ diameter clear PVC coated clothesline wire went through the holes nicely and through brown beads to space out the rungs of the bridge.

The bridge is supported half way along its length by a 2×2 that runs under it and attaches to the horizontal 2x4s of the cage frame on either side. The bridge rung is screwed to the support with 2″ screws, and 7-1/2″ long 2×2 wood posts fashioned to hold the rope are positioned on either side of the bridge are attached to that support. The same sized posts were placed at the far end on the perch platform. The rope was fed through the 1/2″ holes and knotted on the far ends, as well as either side of the middle supports. The bridge is bolted to each perch on the underside with 2″-long bolts, and metal crimping tubes were placed on the long ends of the clothesline wire and cut short. The perch is 1″ plywood and is 18″ x 14″. We covered it with shag artificial turf. The inside of the cat hut floor has outdoor carpeting glued down.

This provides the cats a scratching post in the enclosure as well as a long vertical climb for exercise. When the cats reach the top they are rewarded with the highest perch in the enclosure. The bridge provides an unstable usage scenario to challenge the cats when they wish to explore. Winds make this even more challenging.

Triangular cat cubby and shady deck

We used more sheet stock for the shelves inside the triangle, and for the divider on the lower shelf.  A base deck was constructed by ripping the rough-cut 1×6 spruce into 2-7/8″ wide strips by 28″ long and spacing them out evenly and attaching them to the sides of the 13-1/8″ 2×2 supports. The 13″ x 25″ lower shelf sits on four 7-1/2″ long 2×2 legs, which were screwed to the base deck boards and to the shelf.

The roof was made with more sheet stock, tar paper and cedar shingles. We attached the shingles with the #6 x 1/2″ screws and glued the top layer on so no screws are visible. The outdoor carpet was cut, glued into the 3 cubby holes. The back of the triangle was filled in with cedar boards cut to fit the ‘A’ shape.

Strips of pine, 1×1, were screwed to the underside of the back of the roof to attach the thin cedar boards to. They are set in so the cedar boards are flush with the back of the roof. This provides the cats with privacy, shelter and separate hiding spots from the other cats or outdoor threats.

Ramps to perches

Longer pieces of 1×6 cedar were used for the ramps. Treads/rungs were made for the ramps by cutting thin pieces of cedar and attaching them to the top surface of the ramps, 6″ apart. A 12″ x 12″ piece of plywood serves as the top perch at the peak between the two ramps, and a 12″ x 9″ piece of plywood is the perch on the right side. A 9″-long piece of 2×4 supports the bottom of the ramp on the left because it came close to a stair on the 4×4 post of the cat hut. The perches have outdoor carpeting cut to fit the tops of the perches. All perches are screwed to horizontal 2x4s.

Poplar climbing branch

A 6′ long, 5″ diameter poplar branch is supported at one end by sitting on top of a horizontal 2×4 support. It’s screwed in place with a 5″ x #8 screw. The left end is screwed to a stud in the front wall with two 7″ x #8 screws. It’s oriented on a slight diagonal from front to back of the cage. This provides a chance for the cats to work on their balance. Even Bart, our most clumsy cat, can use this.

After our cats have used their new catio for a while now I’m realizing we might have built it higher than necessary, as they very rarely use the top section. Kittens might be more apt to explore though.

Our friends think the new addition is totally over the top, but we’re really glad we put the effort in and built them a large enclosure. The cats really love their new outdoor space and spend a lot of time relaxing and playing in it.