How to build an outdoor cat tunnel

I have never talked in detail about how I actually built the outdoor cat tunnel leading from and to my outdoor cat enclosure in our yard. I recently built another wire mesh cat walkway for my kitties which presented a good opportunity to finally write a step-by-step tutorial. Cat tunnels are a such great way to let your cats safely enjoy the outdoors even if you don’t have the room for cat enclosures as I do.

I built my cat enclosure before I started my blog which is the reason I never had a full tutorial on the blog. Since we adopted two young cats last year (meet my cats), I thought it was the perfect time to extend our outdoor catio enclosure with some more tunnels and possibly another enclosed space in one of our trees. Let’s see how far I will get this spring and summer.

So let’s get right to it.

How to build an outdoor cat tunnel

There is a big difference between outdoor cat tunnels and indoor cat tunnels. The indoor version is for entertainment and mental stimulation. They mostly crinkle or keep the cats entertained with some attached cat toys which make them play tunnels.
The outdoor cat tunnel’s sole purpose is to keep the kitties safe while enjoying the backyard and fresh air.

How big does a cat tunnel need to be?

Before you start planning and building your outdoor cat tunnel project, you need to make sure that the size of the tunnel will fit your cat. My cats have always big regular size but if you have large cats then you might want to build your tunnels a different size.

Most cat tunnels are about 13 to 14 inches in diameter. My tunnel’s walking surface is 11 inches wide and the mesh part of the tunnel is 14 inches high.

Supplies needed for outdoor cat tunnel

• deck planks (HERE), the amount of planks needed depends on the length of the tunnel you want to build
• pressure treated 2×4 lumber (HERE)
• deck screws (HERE)
• galvanized fence staples (HERE)
• wire fencing/pet fencing, I chose vinyl-coated gauge wire this time around but you can also just use galvanized mesh
• outdoor wood stain (HERE)
• brush for staining (HERE)
• (mineral spirits or turpentine for cleaning the brush)

Tools

• drill (right size of drill bit for your screws)
• hammer
• measuring tape
• wire cutter (HERE)

For the tunnels along the top of my fence leading to the cat enclosure, I used cedar fence planks because they are a lot lighter than the pressure-treated deck planks. Those lighter tunnels along the top of our fence were attached with shelf brackets that I made myself out of wood but I’m sure you can buy them as well. Just make sure that they are weatherproof.

Deck planks are cheaper but a lot heavier. The extra weight is better for my floor tunnels since I didn’t want the kids to be able to pick the tunnels up and mess with them. The cheaper price tag was also a bonus.

Building instructions

• I stained all the wooden pieces before I even started building anything and let it all dry. To me, it’s much easier this way. I love using this stain. It’s a great rich color and really protects the wood. But you can certainly build the tunnel first and stain it before adding the wire fence to it.
• Measure everything before starting the project! This simple step is always the most important part. And every project’s measurements are different.
• Cut the 2×4 lumber in strips to match up with the width of two deck planks lined up next to each other. These pieces will be the bottom support pieces that keep the cat tunnels together.

• I cut one of the deck planks in half, so I could stagger the pieces which ensures more stability. It’s not a must but certainly helps.

• For my design, I needed some extra pieces of wood to add to the tunnel surface because our walkway is on a steep incline/hill and I wanted the cats to have something to hold on to. It’s more like a ladder going up the hill. I did not include this step in our regular tunnels along the fence. It is only necessary on an incline. (view photo)

• Now it’s time to assemble the bottom part of the cat tunnels. Layout the 2×4 pieces on the ground and add the planks on top.

• Then pre-drill the holes where the planks attach to the 2x4s. This is very important because if you don’t pre-drill the holes the wood will crack. (view photo)

• Use two to three screws to attach each plank end to the 2x4s (view photo)

• When you have one large tunnel walkway, it is time to attach the wire fencing. I used 3 planks (2 hole pieces, 1 cut in half) for this tutorial. We made it this big because otherwise, it would have been too heavy to carry which is another factor to watch out for. (I will attach another tunnel section to this part soon.) Lay the walkway part on its side so you can lay out the wire on top.

• I trimmed the width of the wire fence with a wire cutter since I didn’t want the tunnel to be too tall but this is optional.

• Cut the wire fence to the length of the tunnel
• Attach the wire fence with the fencing staples and hammer to the one side of the plank. I hammered staples into every second rectangle of the wire.

• Now turn the planks and fencing around and bend it over the walkway part and hammer in the galvanized fence staples on that side as well.

For this cat tunnel project I chose not to finish the edges of the tunnel with another piece of wood but for the tunnels running along the side of our patio where everything is more visible, I did hide the staples. (see below photos)

Below you can see the wooden shelf brackets that I made to attach the lighter tunnels to the fence.

And here are the kitties using the tunnels and exploring. And if you are wondering, I closed the end of the tunnel with a small piece of fence until I’m continuing with the project.

Maya also loves the tunnels. I feel like calling them walkways though because that’s what they really are.

Willy loves it out here. You can see how the wood aged over the years. They are very durable and have held up great over the years. I need to figure out a way to stain it again. Above is our Lilly cat in the same spot as Willy is walking below.

I actually stained the entire outdoor cat run again which is now nicely nestled in between all of our plants.

Here is my poor skinny old lady Lucy. She just turned 19 and is the last of our old lady crew.

Now I need to fix the upper part of the fence before I continue. The one post is leaning over and needs to be secured first. I actually hurt my back when I was leaning over to attach the staples and am taking a little break before I continue. My plan is to have the tunnels go to the upper patio with a perch in the trees for them to sit with us when we are using that side of the yard.

It is so much fun to see them explore and use their outdoor space. Making enclosed tunnels or walkways for your cats is a great way for them to watch birds and butterflies even if you don’t have room for outdoor enclosures. I think the cat tunnels are much more fun than just sitting in a cage anyway, don’t you think so? And they are really easy to build as you can see.