Cat Door Installation

Do you have a cat?

We do and he is very NEEDY.

He’s only allowed to go outside on days that we will be home. He has our schedule figured out pretty good so on “outside kitty days” he is always underfoot until we let him out and then he cries at the door until we let him in.

This often disrupts whatever homestead project we are trying to accomplish whether we’re inside or out. So we decided to install a Cat Door.

We thought about our options.

Option 1. Cut plywood to fit in a window and cut a hole big enough for the cat covered with a carpet flap. This would be the least expensive option but would have to be placed in the window each morning and taken out of the window each evening.

Option 2. Buy a Cat Door and install it into a door or wall. This has some attractive points such as a professional look, better seal, always in place and flexibility in locking schemes that allows the cat to go out only, in only, both in or out or locked completely. The downside is cutting a hole in a wall or door.

We chose a blend of those two options and put a commercial cat door in a piece of plywood in a window.

This allows us all the flexibility we need. We can put it in the window the night before Kitty Outside Day and set it so nothing can enter but he can go out. This way I don’t trip over him trying to make coffee. He comes and goes as he pleases throughout the day so less stress on the kitty and us.

Installation was simple, though it does take some tools. Power saws speed up the process but hand saws will get it done. I’ve provided Amazon links to the tools I used:

Tape Measure
Black Sharpie
Safety Glasses
Cordless Drill
Drill Bits
Reciprocating Saw
Circular Saw
Hack Saw

Step 1. Measure your window opening and write those measurements down. You’ll want it to be at least 6 inches taller than your cat’s shoulder height (more than that is OK too). Pick a window that is out of the weather. We chose a window onto a covered porch where we could put a table on the inside and outside for the cat to access the door.

Step 2. Weigh your cat so you know what size door to buy. 

Step 3. Acquire the cat door. This One from Tractor Supply will work for cats up to 25 pounds (like ours).  If you use the affiliate links provided we’ll make a buck and it won’t cost you any extra.

Step 4. Acquire plywood. I’d recommend at least 1/2″ up to 3/4″ thick plywood. If you want a finished look you can stain or paint your wood. There are numerous grades of plywood so pick one in your budget that satisfies your aesthetics. You can fill any voids and sand utility-grade plywood to trade time and effort for cost if you’d like. We had some extra siding from the chicken coop build that I cut to size. Another option would be buying a piece from a lumber store. Most of them will make a couple of cuts for free so take your dimensions with you. Remember to measure twice and cut once for accuracy.

Step 5. Use door template to layout hole. There will be a template in the box with your door. Use this and the measurements indicated to layout cut lines on your plywood. I traced the template with a Sharpie Marker. Make sure you have at least 3 inches of plywood left at the top and bottom of the cut out to maintain the strength of the plywood.

Step 6. Drill 1/2″ holes at each angle of the cutout. The picture provides a better explanation of where to drill but these holes will allow you to insert the saw blade to make the cuts around the periphery of your cutout.

Step 7. Cut out the hole. Use a jigsaw, reciprocating saw or a small hand saw to cut along the lines you traced from the template. It is important to stay fairly close to the line but don’t stress if you drift off 1/16″ either side of it.

Step 8. Ensure your bolts are the correct length. I put this step here because at this point you can test fit your door in the opening. The door will come with a few choices of bolt lengths but in my case one was too short and the next was too long. They provide instructions on how to use the thickness of your board and add something to it to get the proper length. My advice when using that formula is that it will give you the maximum length you can use. So cut them a little shorter. I had to cut mine twice.

  • CAUTION: Hacksaw blades are SHARP!

(Wearing work gloves would have prevented this.)

Step 9. This is when you would want to fill, sand and paint or stain your wood if you so choose. We opted to leave ours rustic.

Step 10. Assemble the door per the provided instructions. It’s simple so I won’t go into detail except for a couple of tips.

Lay your plywood on a towel on a table with the outside face down. Find the half of the door that does not have the locking mechanisms on it and put it under the plywood positioned in the opening.

Place the filler piece as directed then place the inside half of the door in position. Pro Tip: As you are lowering the inside half of the door look through one of the four screw holes so you can see where it will line up with the outside half and keep that alignment as you place the door in position.

Drop all four bolts into their holes and make sure they go in straight. If one is crooked you may have to pull the door apart to get it back out. A magnet may help here but I didn’t have one. Once all the bolts are in straight, slide one of the bolt locations off the side of the table. If the plywood feels like it wants to fall to the floor get some help to hold it. Now put one of the retaining nuts in the hole underneath. It should be long enough that it raises the bolt head a little. Use a screwdriver to tighten this bolt VERY lightly such that the entire door will still move on the plywood. Repeat this for the other 3 bolts.

Step 11. Center and level the door. Once the door is in position the way you like it snug down the bolts. Keep in mind that these are small bolts and the frame is plastic, do not over-tighten or something will break.

Step 12. Place assembled cat door/plywood assembly in the open window and close the window onto the top of the plywood to secure it. Remember to remove the screen!!

Remember to train your cat in the use of the door. This is all new to them and they likely won’t understand at first. Show them the door gently but firmly and help them go in and out a few time until they get the hang of it. 

The next few times the cat goes to an entry door to go outside you will need to remind them to use the cat door but it won’t be long until the new cat door is in full use and you won’t need to submit to the cat’s wishes (as often at least).

I’ve added a Tractor Supply link to more – Cat Supplies.

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