Introduction: Built In, Self Venting Cat Box

Picture of Built In, Self Venting Cat Box

This is a self venting cat box I built. It does have a bathroom fan inline but, that turned out to be overkill. I tapped into the vent stack for the tub while I was remodeling the bathroom. Also did all the tile and everything else, really.
The box emits no smell, the hallway down one side traps loose liter before the cats jump out and keeps the dog from getting treats. It was a blast to make.

Step 1:

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Looking in from the back of the shelves during construction.  There is a small closet that goes to the adjoining bedroom.  I sacrificed part of the closet for shelves in the bathroom and the cat box.

Here you can see the pipes leading from a small bathroom fan to A dedicated vent pipe.  That pipe goes up and through the roof.  I added power to charge a cordless razor or curlers (do people use those any more?)  The blue electrical box behind that pipe houses the timer switch. 


Step 2:

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Here is the timer from the front.  At one point I was going to put a motion detector in the box.  Glad I didn't because there seems to be a natural draw in the box that self clears the air.  Not enough to pull heat out of the house.  Just a slow steady flow to removes stink.

Step 3:

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The box is coated with shellack.  Shellack resists soaking in any odor and it's waterproof.  On the floor of the box I poured about 1/8" of epoxy in case of spills.  The finished box can hold water. 2 inches deep (just had to try for fun)

Step 4:

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The box rests on 4 100 pound rails.  It weighs about 35 or 40 full plus a 20 pound cat.  The rails extend out quite far.  The hardest part of the project was building a nice square box inside another one with the right amount of space to accommodate the rails.  I got lucky.  the box slides out smoothly and does not tip at all.

Step 5:

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I also added this neat set of pull out shelves since there is no medicine cabinet.

Step 6:

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The "passageway" down the left there serves two purposes.  That's a plastic door mat cut to fit in the channel. When the cats exit, they don't bring any liter back into the house -it actually works like a door mat should!  It also prevents my dogs from stealing "treats" -they can't get their big Labrador heads in there.

Step 7:

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When the drawer is shut, it works like a charm.  I can open it to scoop into the toilet or replace the litter.  I put the plastic liter box in a 3mm plastic contractor garbage bag and them fill the box over the bag.  Just pick up the sides of the bag and turn it inside out.  No mess!

Hope you enjoy


Step 8:

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After seeing I've missed some level of detail (pardon, this is my first submission and I understand that I've taken much for granted), here is some detail on the venting architecture.  The important item to see is the P trap at the bottom of the image in the stack that the box is connected to.  This prevents dangerous gasses from getting into the home.  Water in the traps seal the stack from allowing gasses into the home.  The best way to avoid any possible issue is to have a dedicated vent stack.


Step 9:

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Contrast on this image is tuned up to help see detail.  After some consideration I re-opened the wall in the closet, disconnected from the vent stack and redirected the pipe for a dedicated vent stack of it's own.  Typically a bathroom fan uses a four inch pipe but the volume of air being moved is small and the fan is very small so it won't be stressed.  Larger fans require larger vents or you'll stress the fan.  (Imagine a vacuum when you suck up a sock)

Step 10:

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This is an image of the finished dedicated stack.  I would have rather kept it in the wall but, that would have been a very invasive project! I sanded the outside of the ABS pipe to rough up the surface for best paint adherence.  The box at the bottom contains the fan.  Since the box comes so far into the closet, I just divided up the remaining space at the bottom with shoe shelves. 


KerrianneP (author)2016-03-25

I'm just coming across this post now (5 years later, lol). Seems like such a fantastic idea! I'm great with carpentry but unfortunately know absolutely nothing about plumbing but I am dying to try this. I'm going to have to do some homework on step-by-step how-to's. Great job!! Thanks for sharing!

Green Silver (author)2010-10-14

Thats eally neat, but I feel sorry for the cat going in the dark.. Can you rig up a solar/battery LED lighting system? 1 LED should do the trick, cats can see 6 times better than us in low light.

KerrianneP (author)Green Silver2016-03-25

Ive heard my cats going in the middle of the night as well in total darkness. They should be fine.

I considered this but, enough light must get down the side to help them see. I have heard them using the box in the middle of the night so I assume that once they learn their way, they are fine.

account3r2 (author)2010-10-14

"I can open it to scoop into the toilet or replace the litter." Dont do that. it can kill seals.

Spokehedz (author)account3r22010-10-14

It depends on where the water is sent to first... If your community dumps your sewage into the ocean, then yeah it would be bad. But if they are like most normal communities then they are sending it to a water treatment plant where all toxins are removed before the water is put back into the environment.

thebriguy (author)Spokehedz2010-10-14

I think your community has problems if they are dumping raw waste into the waterways. Scooping cat poop into the toilet is pretty efficient. If you really oppose, scoop it into a bag and put in the garbage. Or, better yet get a diaper disposal (ie:Diaper Genie). Or you could put it in the garden or compost.

Spokehedz (author)thebriguy2010-10-27

I said ocean, and yes there are some communities that do that around the world. Instructables is not a USA-only website, please be a little more global in your thinking.

The proper way to dispose of poo is to bury it in the yard. That's where it wants to go, and that's where I put it. I just dig a hole a couple of feet deep with a post digger, and drop the poo in it. Takes a second, and the garden never has any rabbit problems because they stay away from where there is a lot of cats.

LesB (author)Spokehedz2015-01-08

So, I assume then that you do that with your own poo also?

Spokehedz (author)LesB2015-01-08

Well, of course!

xdomhnallx (author)Spokehedz2012-12-30

I think it would be a safe bet that any place that dumps raw sewage into the ocean, probably doesn't put cat waste up high on their list of things to worry about. Assuming that there is a water treatment plant downstream from your toilet isn't an American viewpoint. It's a modern world viewpoint. Sure there are still plenty of areas on this planet that are not so blessed with modern conveniences, but again, they are not likely to be on this website looking for green solutions to cat poo. It's a bit condescending to ask someone to be more global in their thinking because they didn't address the specific needs of every community on earth.

Aswa (author)thebriguy2010-10-14

Composting yes, and I agree, I would also put it into the toilet if you use environmentally friendly litter.

But Diaper Genies are incredibly and unnecessarily wasteful things IMHO. There already is enough plastic in conventional diapers, and those machines add an extra layer of scented(!) plastic to the trash.

If one is worried about the well-being of ocean creatures, the first thing to do would be minimizing the use of disposable plastic products.

Just my few cents.

thebriguy (author)Aswa2010-10-27

Actually the Diaper Genies are not the problem - it's the diapers that go in them. Therefore, it wouldn't be a bad use for cat poops (unless you train your cat to wear diapers).

Aswa (author)thebriguy2010-10-27

Well yeah I fully agree the diapers are the BIGGER problem, but I don’t think it’s a particularly good solution to wrap them in yet more plastic.

Basically what I meant to say is, when one is concerned with the health of seals and marine life, then kitty-litter going into the toilet is definitely one of the smaller problems they have to worry about, while disposable plastics are most definitely among the bigger ones – as a lot of plastic ends up in the oceans, even if it has been put into a garbage bin at one point.
So I wanted to underline and agree with your initial statement: "I think your community has problems if they are dumping raw waste into the waterways."
I don’t know what kind of kitty litter you would have to use for this form of disposal to be problematic.

It is actually not a huge issue getting rid of cat poo without any use of plastic really, especially if you put it into the toilet or compost it. So that is why I think a diaper genie for that purpose is wasteful and unnecessary.

vgreen89 (author)Aswa2011-01-09

Actually, one reason California Sea Otters are so endangered is because of a disease caused toxoplasmosis. Cats are the main carriers of this disease (cats have few or no symptoms, and up to 50% of cats--and people have it), and people spread it to the otters by flushing the cat poo down the toilet. More wastewater than you'd think goes into our surface waters which is why it is no longer safe to drink any surface waters in the continental U.S. Moral of the story-- Don't flush your cat crap down the toilet!!!

winterwindarts (author)vgreen892011-11-26

The main source of toxoplasmosis is NOT cats but contamination from raw or improperly handled meat or seafood...or gardening. Please check your facts to make sure that they are up to date-VERY few cases can truthfully be linked to them anymore (less than a dozen in the many thousands of cases every year). House-only cats that are not fed raw meat and do not eat mice or other rodent pests are not carriers as the disease can't last more than a couple of months in their bodies.

When I first got my cats my husband (then fiancee) started in on hinting that I would have to get rid of my cats when I get pregnant so I started looking up RECENT data on it to show him. Almost no one practices pristine enough sanitation in the kitchen to keep toxoplasmosis out of their finished food much less out of their drains from just washing up and thus causing it to enter the watershed (overuse of antibacterials/microbials causing resistance is another rant). As long as there are humans and prepackaged raw meat, toxoplasmosis will be pretty widespread. Just washing hands is enough to get it to enter the watershed. There are no easy solutions.

Just the risk of damage to plumbing is reason enough not to flush clumping litter and I'd be pretty leery of flushing other types of litter.

Pregnancy/human health specific: many people are already immune to toxoplasmosis due to prior exposure-eating dirt as kids being the main reason. Grilling meat and not being careful to use a fresh plate for the cooked meat is another very common source. Prior exposure/immunity can also be tested for in both humans and cats and apparently there are vaccines for both species.

theawesomeninja (author)vgreen892011-07-25

I'm pretty sure all our sewage is treated in a manner that does not harm the seals. They first take out the solids, process it and dry it and sterilize it and use it as fertilizer or bury it. Liquids are also cleansed and sterilized and is labeled as "reclaimed water" used for watering parks and other non-food related plants.

thebriguy (author)vgreen892011-01-10

My poop goes down, so so does my cat's poop. If my cat has toxoplasmosis, I probably do to - so it's really indifferent who's toxoplasmosis does down the shitter. Also, if 50% of people have toxoplasmosis then we're a little beyond anything we can do about it. I'm in Wisconsin, with my own septic out in the country, so it's very unlikely to affect the California Sea Otter. Regulations are rarely one size fits all - I shouldn't be held to the same regulations that a city has...

Spokehedz (author)vgreen892011-01-10

Yes, toxoplasmosis is an issue with the otters... But, he is in Denver which is pretty dang far away from the ocean. And the main issue is that the water treatment plants are NOT doing their job if this stuff is getting out into the waterways... The main issue is more than likely people dumping kitty litter into the trash, which gets dumped into big piles and then the water table gets polluted that way.

And if sewage is getting into your surface water, your water treatment plants in your area are SERIOUSLY out of code, and the EPA should be called out. Yes, 'wastewater' goes out into streams and things, but it is not sewage--which is what you are inferring.

thebriguy (author)Aswa2011-01-10

I'd love to sail out into the ocean and make a giant plastic island from all that floating recycleable. From the pictures I've seen it's an absolutely lovely climate there (and worlds better than Wisconsin this time of year)!

Todd2255 (author)thebriguy2011-05-23

you should never but cat dog or any type of waste in your garden or compost

thebriguy (author)Todd22552011-05-24

But it works so good. Fertilizes the trees and flowers, and keeps the deer away! Doesn't seem to be a problem.

Todd2255 (author)thebriguy2011-05-24

I should have givin a better comment- trees,flowers and the such is fine ones it is composted - but to use in the garden for human food not good . look up on the net under dog waste for fertilizer, you can get a better answer then i can give you. Have a great day.

thebriguy (author)Todd22552011-05-24

Agreed! Never for a food garden. Thanks for clarifying.

jimr77777 (author)account3r22012-01-28

I thought that the cat litter (combined with the smelly stuff) would clog up sewer pipes, and that was why not to flush it... do any plumbers know the answer to this?

BTW - great inst-able!

veeguy (author)account3r22011-02-11

If you are on a city or town sewer system, you don't need to worry about "killing seals". The biological process used to clean the sewerage (activated sludge or oxidation ditch) will kill off the toxins. If that doesn't do it, the chlorine or ozone disinfectant will do the trick. If you think about it, hospitals flush hepititus or other contageous tainted fluids down the toilets all the time.

Denver_80211 (author)account3r22010-10-16

I actually don't do this very often. While I do care for all animals I hope that Denver's septic system does a good job cleaning waste before it could impact any wildlife (or non-wild life!). I would add that flushing cat waste is a BAD idea if you use clumping cat litter. We're using recycled newspaper pellets which dry things out and don't adhere to waste.

AudreyGreenwood (author)2014-09-25

The fellow commenters are taking this issue way too densely. The objective is to accept that this cat box idea is ingenious and what happens to the litter afterwards is an entirely new topic. There is no need to mix them up and make it look as though this instructable isn’t going to work out for anyone. You can decide for yourself what works best for your household and modify accordingly.

katerlyn (author)2014-07-20

I am amazed all these years I missed this wonderful work of art, could you put "litter box" in the title to reach more people? Thank you for your instructable.

reddog92396 (author)2012-12-20

Rock the cat box

LardaLot (author)2011-07-25

very glad to see this project. just to say, my cats are sort of "cave-cats" and they would love this. will build something like this soon :)

riff raff (author)2010-10-14

How long did it take your cats to get over their natural apprehension of the new litter box and start using it?

Denver_80211 (author)riff raff2010-10-16

No delay at all. They were in there immediately. I let them use it outside the box and then put it inside so the scent was the leading indicator.

Not certain about natural apprehension to small spaces. If I leave a box or paper bag out, they are in it paying immediately. I've know many cats to share the same love of confined spaces. Clearly my observations don't mean all cats are like that. Could be a breed specific behavior?

chuckr44 (author)Denver_802112011-07-14

Most cats I have met love confined spaces: shoe boxes, bags, under lazy boy chairs, anything.

elguappo (author)2011-07-09

Fantastic idea.
I hate having cat boxes in a room and the smell wafting around no matter what you do.

tinker234 (author)2011-06-07

wow if only we had a self cleaning thoughts anyone

Tangoforce (author)2011-02-03

Brilliant idea. The tunnel is excellent as it appeals to a cats natural curiosity and we all know they need a bit of help using the toilet!

Very well done, its excellent!

zuruiboy (author)2010-10-15

Great post - very well done. And don't stress killing seals....the sewer in Denver is not very likely to make it to an ocean, lol!!

vgreen89 (author)zuruiboy2011-01-09

No, but it probably goes into at least one river, where I'm willing to bet other animals (beavers, muskrats, etc.) live that could be also contract toxoplasmosis and be affected by other harmful substances that may be in your cat's litter. However, these animals are not currently being pushed into an extinction vortex like the sea otters.

redneckuprising (author)2010-12-03

This is just awesome. But there's no way in hell MY cat would be able to fit through that hole...

Mason5280 (author)2010-11-18

Hey there! Great idea - if I had cats, it'd be in the works! And how is Jeff Park? Denver native here - Lived in JP 1999-2006 before immigrating to Canada. Miss the city, hood and the beautiful old Victorian I renovated there. Cheers!

AfricanMystic (author)2010-10-28

I just love this box. It's so neat and well executed. Plus it's a great idea.

DanteDante (author)2010-10-05

That's pretty slick! I'm trying to decide on a place in my house I can sacrifice the cabinet space for this. Seems definitively worth the effort. Nice work.

Denver_80211 (author)DanteDante2010-10-05

Using a vent stack was a bonus option I had while remodeling the bathroom.

All you really need is a pipe that leads outside. Driers frequently vent out half a basement window (don't tap into the drier line!) or if you are really motivated, drill a hole out the wall of the house. The pipe I connected to was only 1.5 inch diameter. This is no 4 inch smoke stack :)

I have seen other projects here that filter the air if you are really stuck inside. Anything is better than open litter.

I have two cats and we never notice any smell -so we need to clean out on a schedule!

bitterbug (author)Denver_802112010-10-14

If you're using the vent stack put a trap on the line, otherwise you risk methane (explosion) or hydrogen sulfide (fatal poison) getting in.
Cool design though.

tkjtkj (author)bitterbug2010-10-14

just what kind of trap works without being filled with water? Traps in toilets and tubs work ok cuz the pressure/weight of the exiting water assures flow around the 'inverted U-shape' of a typical sink trap .. Even a flap valve (used for air flow) would then require the fan .. you'd need positive airpressure to cause air to exit , On the other hand, i doubt any building inspector would approve of such a 'tie-in' to a sewer line .. Sewer gases are deadly .. and a flap valve could never assure zero reverse air-flow.

Now, if all above is solvable, there's still the issue of a noisy fan de-motivating the cat! A sensor could be arranged (think: proximity-sensor night light, etc) to turn off the fan if a cat is near the entrance ...

You did a good job but the issues i outlined above are not trivial ..

bitterbug (author)tkjtkj2010-10-14

Something like one of those "ping-pong ball" valves would make a decent trap if there wasn't enough air pressure to push past water.

tkjtkj (author)bitterbug2010-10-14

Yes, good thinking .. but would you bet your life and the lives of your family members on a pingpong ball? Sewer gases are in that pipe.
That tub drain is connected to the same drainpipe that the toilet is connected to: a vertical ? 6" dia iron pipe up thru the roof and open at top; each connection (tub, etc) has a 'U' tube shaped 'gas trap' whose water content is replenished with each 'flush' or drainage. A plastic ball in the presence of sewer gases .. mm..well, I'd not put my kids' lives at risk .. I dare say the Building Inspector wouldn't either

and his device doesnt seem to use the fan,..not sure on that .. but a light pingpong thing still would require positive pressure.
Now , if he had a totally separate pipe, that'd be different story .. would need any valve or trap at all ... but it would need some sort of cap at the top ..
and the bigger its diameter, the better ...

bitterbug (author)tkjtkj2010-10-14

Ha. I didn't mean make one with an actual ping-pong ball. :)
I just couldn't remember the term 'check valve' and described it so that anyone who has seen them would know what it was.
Provided that the check valve used a light spring it would create positive pressure but then you'd need a way to get the airflow up to speed to overcome the spring.
Old vacuum motor?

tkjtkj (author)bitterbug2010-10-15

ya, maybe. But my comment wasnt about the ball, really .. it was about the fact that this is a potentially dangerous and illegal hookup to a sewer vent line that is dangerous to the residents.

How to achieve the airflow is not a big hurdle; how to get it out of the house is not a great hurdle IF and ONLY IF its not done via a sewer drainage line.

Were someone sickened (or worse!) by sewer gas backflow out the presently-untrapped line, i'd sure feel guilty had i not spoke up.

That such an event could happen by illegal construction would be an unnecessary tragedy.

Prime Rule of Engineering: "There is NO such thing as an accident!" There is ALWAYS a preventable reason that contributed to the (usually) series of multiple conditions that lead to such things. This rule is why the FAA, eg, takes as long as is necessary, sometimes many many years, to understand events related to a plane crash. They never merely say .. 'oh well, just an accident...' !!

About This Instructable




Bio: I frequently get the bug to build something. I don't like to do anything half-assed. I want to see how many functions I can ... More »
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