Cat Flap in a Baby Gate




About: I am a graphic art hobbyist, web cartoonist, and wannabe electronics hobbyist. Other hobbies: cooking, baking, exercise, computers, video games, trivia, and some more I'm probably not remembering.

Good day!

My wife and I live in a 3-level townhome. We have a cat and two dogs. The cat has run of the house- and in fact needs to have access to the 3rd floor. However the dogs should not be up there! My challenge: take a baby gate that we already own, and make a cat flap so the cat can go up and down the stairs without letting the dogs through.

We already had the extra-tall walk-thru baby gate that you can get at Babies 'R' Us. We had it at our old home, where we used it for the same purpose - but there, the cat was able to get around the gate by going through the railing bars. Here in our new home, the bars are too close together, and the cat can't fit through.

Ready... Go!


Step 1: Supplies (and a Comment on Safety)

Stuff I needed to do this project (your supplies may vary):

Copper pipe holders (1/2 inch) -- not sure if that's the official name, they're u-shaped with tabs on either side, and holes for screws or bolts to pass thru.
Four Round-head bolts, four washers, and four nuts for the bolts. I used #10 coarse thread bolts.
1x2 wood. This wood is poplar, inexpensive at Home Depot or Lowes. I used 20 inches (2 x 10" lengths).
Screen material (I already had this from repairing window screens)
Packing tape (you can use any durable tape, ie. Gaffer's, Electrical, Duct...)

Tape measure or ruler
Needle nose pliers
Regular pliers
Flat-head screwdriver
Staple gun
Drill and drill bits
Dremel tool with jigsaw attachment, or reciprocal saw, or hacksaw
Dremel tool with barrel sander bit, or sandpaper and lots of patience
Metal blade for the saw of choice above
Clamps (I use quick-clamps)
Razor, scissors or box cutter
White semi-gloss or gloss enamel spraypaint

Probably more stuff I'm forgetting.
Ah, well. I'll add them in later if I remember more.

A Note About Shop Safety, aka I Am Not Responsible If You Sever A Limb Or Injure Yourself In Some Other Grievous Manner:

Saws are loud, sharp, and create sawdust. They can cut off body parts, and cut holes in bodies. The dust that a saw makes can fly around in the air getting into eyes, mouths, ears, and skin. Saws are also loud and can damage your hearing. Electricity can also kill you.

Please wear EYE and EAR protection at all times. You may consider wearing a dustmask and work gloves, to prevent any metal shavings from becoming splinters or being inhaled into your lungs. Also please keep electric cords out of the path of saw blades.

Thank you.

Step 2: Remove the Door From the Gate

To make this project easier, we need to remove the actual door from the gate.
This isn't difficult. The door is held in by a spring-loaded hinge pin with an E-clip on the bottom.

Push on the hinge pin and the E-clip becomes visible. Grab the clip with your needlenose pliers, and yank it off. The spring will push the pin past the top of the hinge, and you can pull out the whole assembly.

The door will then lift right off. Bring it to your workspace.

Step 3: Cut a Hole in the Bars

Anchor your gate door to your work surface with clamps, and measure out the space you want to open up for your cat flap. I measured across 3 bars (four spaces) to get 10 inches. So I wanted a 10x10 square hole when I Was done, about 9 inches off the ground (the rise of one step, so the cat could get through the gate - if I put the hole at ground level, the first step would block the hole).

I marked the cuts with pencil on the bars, and used the dremel saw with a metal jigsaw bit to cut the bars out.

Save the bars for future projects, or at least keep one nearby to verify the size of the holes you'll drill in the one-by.

Step 4: Cut and Drill the Cross-Braces

You may come up with a better idea than this, but here's what I did....

I took a length of one-by-two wood and cut two pieces an 8th of an inch shy of 10 inches, the width of the hole I have just made in the gate door. An experimental and adventurous person could cut it wider, and then dremel out the ends so that they're concave and will slide in-between the bars. I thought of that only after I used something else to secure the cross-braces to the outside bars (in the next step).

using the ends of the cut bars ON THE GATE as a guide, mark the 1-inch side of the board to drill some holes. The pipes in this gate are 1/2" outer diameter, plus a few 64ths of an inch. I would recommend tapping a nail or screw into the center points where you would like to drill, so that the drill bit itself doesn't slide along the surface of the wood before it bites. It's not bad if they're a little off-center but you don't really want them too far off.

When the holes are drilled, use a piece of scrap pipe from the last step to test-fit the hole. I used a 1/2" twist-bit to drill a hole about 3/4" deep (since a 1x2 is really only 1.5" wide). The holes were just a smidgen too tight, so I used a drum sander bit on my dremel to widen them ever so slightly. After a few minutes' work, the holes were a good fit.

When you're done, test-fit the bracers into the gate door itself. It may take a little work but it should pop right in and hold pretty tight.

Step 5: Bolt the Bracers to the Gate (possibly Optional)

This step is possibly optional, but I take no chances!
After lining up the bracers and placing them in the gate, mark which is the top and which is the bottom.

Set the gate aside, and dig out your copper pipe retainer bracket things. If I ever remember what they're really called, I'll fix this instructable up.

Using your needlenose pliers and regular pliers, straighten the tabs so the bracket is U-shaped, not speed-bump-shaped. This takes some practice, and I wish I had a video of this so you don't have to destroy as many of these as I did getting it right, but it's mostly trial and error. Grab the flat tab as close to the bend as you can with the regular plier, then work the needlenose in as close as you can get it to the regular pliers' nose on the other side of the bend. Straighten the bend slightly, then move the needlenose closer to the regular plier. Repeat until straightened.

Because the brackets I got were only 1/2" I had to widen the large curve slightly to fit around the 1" end of the 1x2 (which is really only 3/4"). I could probably have made this look nicer -- instead of straigtening the 90-degree bends, I could have added another 1/8" past the existing ones, so the 1/2" curve bend fit snug to the pipes and then the bracket itself would fit snug to the board. Ah, well.

Test-fit the now U-brackets to the ends of your bracers, and mark the holes for drilling. Try to get the brackets in as close as possible, they should be tight when they're finally attached. And, mark your holes carefully. The U-bracket holes should align on exact opposite sides of the board.

Once that's done, take the boards out, and clamp them down. Drill at the marks holes large enough to accomodate the bolts you got. The bolts themselves should fit thru the holes in the U-brackets, so the hole you drill should be about the same size.

When you're done drilling, re-assemble the hole in the gate, and bolt the U-brackets onto the ends of the boards around the bars, and tighten down. The Hole is now COMPLETE!

Move along...

Step 6: Paint!

This is a no-brainer.

Paint the whole contraption so it's all the same color.
Set up newspapers or dropcloths or plastic to protect your work area. Don't forget to turn the gate door over and around to get paint on all sides and in all crevasses.

Safety note: Always use spray paint in a well-ventilated area unless you enjoy raging headaches. I dunno about you but breathing this stuff definitely ain't enjoyable....

Step 7: Make the Flap

My cat won't go through a flap she can't see through, so I made the flap out of screening material.

Note, if you don't have any other animals small enough to go thru the hole, you don't NEED a flap. We own a dachshund who could fit thru, but is too skittish to press through the flap, so this keeps her out of the forbidden zone.

I started by measuring the opening, and cutting a piece of screen material narrower by a quarter inch than the hole, but longer than the hole is tall. This allows me to attach the screen to the top bracer, and the flap will then swing freely.

Cut the screen with the box-cutter. I placed a piece of scrap wood under the screen to protect both the blade of the cutter and my concrete floor.

Once the screen is cut, "selvage" the edges to prevent them from fraying.
Anyone who's seen my other instructable on Sticking Suction Cups to (some) Non-Smooth Surfaces will know I like packing tape. You could use Duct tape, Gaff tape, Electrocal tape... anything durable. (Gorilla tape is probably overkill.) Black duct tape or gaff tape would probably look better.

Cut the tape to the length of a side, and place the edge of the screen in the middle of the tape. Fold the tape over to seal the edge.

Next, play a little game of "alignment" to get the screening in place against the back of the top bracer so that the flap will swing freely. Use the staple gun to tack the screen in place. If the staples don't go all the way into the wood, tap them in, gently, with a hammer until they're flush. If you tap too hard, the staples will break thru the tape and screen.

Voila, done.

Step 8: Reassemble Gate, and Install

You're done!

Re-assemble the gate hinge by placing the plastic washer, then the spring (narrow end towards the top of the hinge pin) on the hinge pin, then pushing the hinge pin thru the hinge and snapping the E-clip back on.

Install the gate according to the manufacturer's instructions.

After installation, I added a home-made stepstool to the front of the gate so the cat could walk thru easier. On the bottom of the back of the stool I attached magnets with short lengths of chain attached to magnet plates, so that the stool could be loosely attached to the gate door. When the gate is opened or closed, the stool moves with it, making it easier on my wife and me... we don't have to move the stool around to get in and out of the gate, it's just easier.

The stool was a relatively simple project -- a piece of scrap plywood with four holes drilled in the bottom, four table legs bought at home depot screwed into the holes, three pieces of 1x1/4" trim nailed around the edge of the ply (for looks and to prevent delamination), a few coats of stain and seal, then the jerry-rigged magnet contraption to hold it all in place.

Thanks for reading!



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    36 Discussions


    10 years ago on Introduction

    Greetings, very nice Instructable, nice clear pictures and instructions. Kudos. As a contractor I am frequently called upon to solve this very problem. I have in many cases installed a wooden storm door with a commercial cat flap cut into the bottom panel. This allows free air circulation, kitty access and keeps the woofs on the other side. Lots of folks also set up kitty food and literbox in attached garage and install cat flap in door to garage. For me it's cheaper to buy the ten dollar cat flap and cut it in than to custom fab one, for a customer.


    10 years ago on Introduction

    This is a pretty classy solution, and very well presented. Nice job!

    I tend to agree with the earlier comment about not completely trusting this with small children, unless they are supervised, and especially with stairs involved. However, I never saw a baby gate I really trusted anyhow, and built my own. I never took any pictures of them, but they're similar to what I built to separate the 24 house dogs here (mostly rescue dogs being fostered) into compatible groups. No baby gate will keep in a determined, medium-size dog, even our Goldens. If they really want to go over or through it, they can. And considering the price of baby gates, anyone can build a better one MUCH cheaper.

    I am a bit puzzled about the need for a cat door -- even our antique, obese cats have no trouble jumping up onto, and then over, our 37-inch tall gates, even the one going to the basement stairs, which is a much longer drop on the other side. It's hard to believe anyone has cats any fatter, or older, than ours ... but maybe it's just a matter of what they've gotten used to.

    Our dog gates, made out of scrap plywood and replacement mesh floors from dog crates, are probably overkill for most people, and the mesh is only necessary because we heat with a wood stove and need lots of air circulation. The dogs also like to look out through the mesh, too, it seems. Probably other, cheaper mesh would work, but we wanted something that an angry Great Dane couldnt get through, and something a dog couldn't get his paw caught in. This strong mesh also adds some structure and stiffness to a thin plywood gate.

    Personally, I wouldn't trust any gate that wasn't securely hinged to the wall with long screws. The way we mounted ours also doesn't interfere with the regular door, since we mounted to the outside of the door jamb, past the "stop" trim that the door closes against.

    Anyway, for whatever it's worth, I posted a couple of photos of the dog gates we built. I'm also working on a "slider" gate, like a pocket door, for an unusually wide opening (38"). Hint: if anyone tries a similar gate, use a lot more hinge than you think you need, or eventually it'll sag and your lockbolts won't line up anymore. Remember that dogs WILL lean on the thing, even if you don't.

    Link to dog gate photos:

    Dog Gate

    2 replies

    Reply 10 years ago on Introduction

    Very nice solution you have there. Re: need for cat flap, my cat has luxating patella and arthritis, and will not jump more than 2 feet off the ground. This is designed to preserve her comfort. As it happens, we no longer use this cat-flapped gate, first because it just kept getting in the way, and second because a family member who did not listen to me, taught the dachshund it could get through the cat flap and defeated the entire purpose for the gate in the first place. (Sound of me pulling my hair out.) I took an old bookshelf and rigged a hook-and-eye catch to hold it upright against the bottom step. I attached magnet plates to it, and the stepstool I made for the first gate now just attaches directly to the new one. Our shepherd can jump over this barricade if she wants to, but she knows when it's up it means "no upstairs for you" and she stays downstairs (she's smart, that one). She's not the one I'm worried about anyway. It's definitely NOT child-proof, but gets the job done for now. The barricade is just at 2 feet high, which the cat can lever herself over two legs at a time (or use a chair as an intermediate step to getting over it). And it does just fine at keeping the dachshund downstairs, since the wiener-dog hasn't figured out yet how to bypass this new security measure. Ah well.


    Reply 10 years ago on Introduction

    Poor kitty ... maybe because all of our cats are rescue cats originally "outside," they've all been orthopedically very healthy, even the 12-yr-old pear-shaped ones that can't keep away from the food bowl, which is on top of some dog crates, so they have to jump up there, too -- maybe 30" or so. When we first started talking about dog gates, we pondered the cat problem a lot, not realizing how far they could easily jump. We had thought about putting cat doors in one or more of the gates, since we had always rescued medium-to-large dogs, but then we got a couple of little beagles, which killed the cat-door idea. Fortunately it isn't necessary now, but I think about the possibility in case one of our old cats gets too feeble & rickety (like me). There really isn't any reason they need to get into the bedrooms or basement, but I'll try to accommodate them if I can. And we'll still need to find a way to feed them (and not the dogs) if someday they can't jump up on the large dog crates where their food is. I wonder if your "steps" idea might work if you could design something narrow enough for a cat to negotiate, but still not wide enough for a small dog to climb ..... or narrow, ramp-type things at the edge of the gate, covered in carpet scraps. With the gates I now have that might interfere with the latches, or keep the gate from going flush against the wall when it's open. Definitely food for thought, though. I suspect my gates are now child-proof, from one side anyhow, but purely by accident. We put those two slider-latches in, figuring that we'd very seldom use the bottom one ... maybe just if we left the Danes alone in there while we were gone a long time (seldom happens anyway). However, we discovered that even though you have to pull the knob out to slide the latch to UNLOCK it, it doesn't require a pull outward to slide the latch to LOCK it. After several dogs locked the bottom one accidentally, apparently by just rubbing against it while lying down in that "corner," we realized that a dog could lock us in the bedroom, since it's almost impossible to reach that bottom latch from the other side. That does make the thing nicely child-proof (from one side), but for our use I'll have to fiddle with it. I think one of my insulin-syringe caps will fit into the bolt-hole in the door jamb, but can't remember to take one in there and check it. Seems like no matter how carefully you plan these little projects, there's always something that needs fiddling later. As with your gate, I know that several of our dogs could jump the gate if the right stimulus occurred, but so far none have tried. I considered making little extensions that could slide up to make the gates "higher," but then I consider the possibility of a fire when we're not here .... and I leave well enough alone. There is no foolproof way to cover every eventuality, so we just have to play the odds and make the best guess we can. And these are still a lot better than hearing the plastic or wooden baby gates come crashing down the hallway, sometimes worn like a necklace by some ornery dog.


    11 years ago on Introduction

    great Instructable! I have the same dilemma--cat food in the basement and three golden retrievers who would love to get down there and have a little snack. I bought one of those gates with a a cat flap but it was too tall and around $80. Your idea is #1 on my to do list for the weekend!


    Reply 11 years ago on Introduction

    we had the same problem when I was a baby and my dad bent the bars apart enough for the cat to get through but not me (unforunately for him I was a climber and escaped from the superhigh cot over the gate and down to the kitchen


    Our dog yards are all 5 or 6-foot chain link, and I had to wire up plywood triangles (horizontal) into the corners to keep the climbers in. Even then, several (usually small or medium-sized ones) could climb up the chain link without bracing against the corners. Several Golden Retriever puppies, less than 7 weeks old, taught themselves to corner-climb 4-ft chain link sections. One champion mongrel could do the ten-foot sections in our kennel. One caveat if you have a "climber" -- it killed that mongrel girl, and quite terribly. She would grab the chain link with her jaw and pull herself up, holding with her paws. After doing this dozens of times, one time her jaw got wedged somehow and her feet slipped. I won't describe the horror, but the vet couldn't save her. If I ever see one like her again I'll use the electric collar to discourage that trick at all costs. Pet owners often underestimate how agile, or clever, their furry friends can be. I've seen several cats than can open regular doors, and dogs that have learned how to crank down car windows or lift standard double-hung windows in a house.


    yeah two kittens in a tiny room at night, after three nights they had figured out the door, a week later they were heavy enough to open it, simple door handle they jumped for a while till one grabbed it then the othe just pushed the door open. Our cat now Lucy love laptops, she sits for hours trying to figure out how she's making things happen on the screen, she sit and paws at buttons for hours, one time she managed to open media player and scare the hell out of herself it was hilarious, I laughed till it hurt... That's sad about the climber your had, then again I could have went that way myself as a child, I climbed out of my cot (already the tallest one then extended) walked down the hall, I preffered climbing the over the bannister rail than the baby gate, then did that outside of the stairs thing down to the bottom, I believe this to be why my fingers nearly reach my knees when i stand up straight with them outstretched


    Any door that has a latch-type knob (instead of a round handle) is pretty easy for most animals to figure out. Our new storm door has to be locked to keep dogs in; it took about two days for six or seven of the house dogs to learn that if they jumped up and pushed the handle, the door would magically open. For the same reason we got rid of the fancy European-type handle on the back door and replaced it with a regular round handle.

    Even horses, who are a long way from being the Einstein of the animal world, often learn to manipulate gate latches. Their lips & tongue are nearly as "prehensile" as fingers. One guy that boarded some of our horses kept finding them out taking a stroll down the road, having opened several types of latches he tried. Finally he went to a combination lock on the chain, and wouldn't let the horses see the combination when he opened it. He was only about half-joking there ....

    Since we do dog rescue, most of my life often seems to revolve around proving that I can outsmart the critters. At best, I am only slightly ahead most of the time.

    One thing I have learned about child or animal "gates" -- there is not one on the market that isn't mostly worthless. Even those that are secure at first will, eventually, get sloppy or wear to the point that a kid or dog can push against them and get through. Only if you make your own can you be certain it's foolproof. Those that aren't willing to invest in hinges or some slider-frame like in this Instructable, firmly attached to the frame, apparently don't value their children very much.

    Knowing how inefficient the government always is, why would a rational person rely on some plastic piece of cr** just because it's approved by the Consumer Product Safety Commision?


    Reply 11 years ago on Introduction

    I misspoke in my comment above -- my reference to a slider-type frame is to a different Instructable, where the child gate is modified with wooden frames on either side, screwed to the wall. Gates that rely on friction-fit are NOT secure, period, and should not be relied upon except as a deterrent ONLY.


    Reply 11 years ago on Introduction

    Absolutely true, regarding deterrent. If you have well-trained pets, then deterrents are sufficient to keep them under control. As it happens, this mod to the gate ended up needing further modification, because one of the dogs did figure out how to defeat the system. Currently it's holding fast, but soon enough we'll need some other novel solution I'm sure. All this so the cat can go upstairs, but not the dog. I'm thinking of just getting rid of the dog. And the cat. :P


    Reply 11 years ago on Introduction

    Believe me, I sympathize greatly with your pet-control problem. We currently have about 12 dogs loose in the house (haven't taken a head-count lately), and since there's always a couple of new rescues waiting to find permanent homes, isolating this pack into compatible, "safe" groups is essential. Also, there are always one or two (usually the newer ones) who are fine normally, but when left alone for hours MIGHT get into minor trouble -- garbage can, chewing, etc. It's just safer to split them into 3-4 confined groups and avoid problems. Same problem as most people, just magnified & complicated somewhat. One thing we've found is that, given enough time & unpredictable circumstances, almost anything can happen. Some stray bitch in heat wanders thru the neighborhood & the boys (neutered or not) get a little bit nuts ... someone knocks on the door & cranks them up .... they see a chicken or duck in the front yard & old predatory instincts muddy the waters ... Murphy's Law prevails. If your latest fix doesn't stop the dogs, you might consider the solution we finally settled on, since you obviously have great mechanical skills. My wife cut a scrap piece of plywood to make a half-door, cut out most of the interior for a screen, and hinged it to the door jamb. After she sanded & stained it, finishing with a superfine 2000-grit finish, it looked so good that we blew ten bucks or so for fancy brass hinges and a nifty sliding brass bolt -- one that you have to pull out on the knob before it "slides." Since the wood was scrap, the only cost was maybe 30 bucks in miscellaneous, and everyone admires the thing. I'd bet money that even our two Great Danes couldn't bust thru that. Most people wouldn't even need the cut-out for screening, but we heat with wood & circulation is more important than with central heat. In your case, you could just use a nicely finished (or painted?) piece of plywood with a cut-out for the cat door. One other caveat in my long-winded comments -- dogs can jump really high, and even my 3-foot-high gate could be jumped by many of our dogs, but the furniture is arranged so that they don't have a clear shot at it. I doubt that I'll need it, but I have a modification (in the back of my head) for a one-foot extension for occasional use when we're gone for longer periods -- fortunately a rare occurrence. However, in case of fire, I'm not sure about this -- maybe it's better to leave it so a badly-panicked animal could jump the gate? You might consider doing an Instructable on your modification, too. Any idea to improve pet or kid gates can be valuable to us all.


    Reply 11 years ago on Introduction

    Neat ideas, I'll have to think about them. Our big doc could jump the gates if she wanted to, but I'm not really worried about her. It's the little one that is a problem, and she is very skittish of flaps and gates and refuses to use them. the addition of a purposefully rickety stool in front of the gate was enough to keep her from going through the flap, since she's small enough to do it otherwise. Then my mom, bless her soul, got it in her mind to TEACH the dog how to go through the flap. Yes, teach the dog that we DON'T want to go through it, how to. And the danged dog learned it in ONE TRY! The modification wasn't much -- we replaced the screen with a piece of black art foam and placed wedges on the sides of the stool so the only way through the flap is straight through, with no ability to see what's on the other side. This was enough to make the little dog skittish enough of the setup again, but it won't work for long. I'm thinking of putting a few holes through walls and some rigs that only the cat can jump up to and down from so she can go through the house wherever she likes (kind of like a hamster habitrail for a cat). Dunno if my wife will go for it, though. I like your construct-a-gate idea, though, I know a few places that could come in useful in my place, and look a lot nicer than the white-bar gates we have up now.


    Reply 11 years ago on Introduction

    "Big dog" is relative anyhow. My two Great Danes are 215 lb & 195 lb. A few years ago I thought of my Boxers & the Rhodesian Ridgeback as big dogs. Now they seem more like hamsters, by comparison. If one of the Danes ever gets injured or real sick, I'm not entirely sure how I'll load them into the car .... Might be an instructable there if I can figure out a wheeled trolley out of PVC.


    Reply 11 years ago on Introduction

    I like your hole-in-the-wall idea. I'll keep it in mind. If you go that route, you might consider a "half of an idea" I've been playing with. Since our main heat source is a woodburning fireplace insert (with blower fan) in the living room, that room is really warm and the heat eventually migrates down the hall to the BR's. We sometimes use space heaters there, as a result. Since the upper foot or so near the ceiling of the LR, above the doors, is really, really hot, I'm planning on cutting a 4 or 6" round hole high on that wall to install an electric fan, maybe thermostatically controlled. Since it'll blow that very hot air out into the hallway, I'll use a short section of PVC pipe for the fan housing, and attach a 90-degree elbow on the exhaust side to blow the hot air straight down the hall to the BR's (aimed toward the floor). If you line your "hole" with PVC like that (or use a 4" dryer vent kit?), it might look finished enough to not offend your wife. I suspect some PVC plumbing parts could be found, or adapted, to make nice trim pieces on both sides of your wall ... then paint to match the wall (or the rest of the trim). Depending on the size of your cat, a 4" dryer vent kit might not be big enough, or might need a little platform on each side ... maybe cut a piece of PVC about a foot longer than the wall thickness, and then trim the excess on either side to leave a 6" platform the cat could jump to? Nicely cut, sanded & painted, it might not offend She Who Must Be Obeyed :-) I think I've got someone to loan me a digital camera, so I may be able to do some pictures of our first gate and the current gate we're building (#2 of 4). If so, I may try to do my first Instructable Instructable, if I can figure out the process. The third gate will be very different, a "slider" with no screening, sort of a home-made variation of that "A Better Baby Gate" Instructable. The last three gates were cut from a single piece of nice birch plywood, so the wood cost was only about 8 or 9 bucks each.