How to Build a Cat Tree House

Decide where you want to place your cat tree. It is easier to build it where you want it to go rather than trying to wrestle it into place after the fact. Select a piece of plywood with dimensions at least one third the size of the crown of your cat tree or larger. For example, if your branches will spread 10 feet in diameter, your base should be at least 3 feet by 3 feet. This will keep your tree from falling over while in use.

Select a thick tree branch about 4 inches in diameter for your main trunk. If it has branches, keep the larger ones, but cut away any small branches. This makes it easier to fill in the additional branches where you need them. Decide whether your cat tree will lean into a corner, stand upright, or be attached permanently to the wall.

Cut 2-inch thick branches so that the smallest twigs are gone, leaving larger branches intact. Use a paintbrush dipped in bleach to coat all surfaces of each branch until the bleach soaks into the wood. This kills mold and should drive out any insects. Allow branches to sun dry on a table or bench. Once branches are dry, repeat treatment using a commercial fungicide solution. Seal all branches with clear acrylic wood treatment after the bleach and fungicide have dried for at least a week.

Place main branch in position on the base plate, either leaned against the wall or upright. Toenail the branch to the base plate by drilling 1/8-inch diameter pilot holes diagonally through the main trunk and into the base. Attach trunk to base plate using 2-inch long, 1/4-inch diameter wood screws. Screw through the base and into the floor if you do not intend to move the cat tree elsewhere in the room. This creates a more stable base.

Miter and cope branch ends so that they fit against the main trunk nearly flat. Mitering is cutting at an angle and coping is hollowing out a piece to fit a curve. Drill 1/8-inch diameter pilot holes through the branch into the main trunk and attach using 3-inch long, 1/4-inch diameter wood screws.

Decide where you want your platforms. There should be at least one platform that is wide enough and long enough for all your cats to lay down together, even if they do not normally do so. This ensures that there will always be enough room for your cats to walk past one another without sparking territorial disputes. Platforms should be close enough together for your least agile cat to climb from one to the next, while still providing enough challenge to your other cats. Make sure there are enough platforms at the highest point on your cat tree to accommodate all of your cats at once. Attach platforms by drilling into the branches and screwing the plywood into place. Screws should be no more than 4 inches apart along the branch, for greatest stability.

Cover all platforms with carpet remnants, either glued in place or carefully stapled. If you use staples, make sure to hammer each staple all the way into the wood to prevent cats getting claws stuck or being scratched. Use L-shaped wall mounts with molly bolts, or metal straps to attach the main trunk to the wall for greatest stability and safety.