Outdoor Litter Box





Introduction: Outdoor Litter Box

I share my home with two cats. Living alone with my cats has been very satisfactory with a conventional indoor litter box. But, my girl friend and I have been talking about her moving in with me recently. She has two cats of her own. We would then have a house hold of four cats. My home is not big enough for the litter boxes needed to satisfy these four cats. I have no interest in having a home with mulitple litter boxes all over the house so, this is my solution. It removes the litter box out of the equation as far as the interior of the home and since I'm putting it on our screened in porch I've added a door in the front to let them go out onto the porch too.

Step 1: The Box

I actually got the whole idea when I saw this Suncast box (Model: VDB19500 Backyard Oasis™ Storage and Entertaining Station) at BJ's Wholesale Club but Home Depot also sells them and thought this would be perfect. It has two doors that open in front and a lid that opens on top making it very easy to get into it to clean the litter boxes.

Step 2: The Bins/Litter Boxes

I originally wanted to do one big bin to use as one big litter box but I couldn't find a bin with the right dimensions. So I chose to do two bins/litter boxes instead. They are still rather large since each one holds 40# of litter to get a 4 inch fill of litter. I found these at Walmart (Sterilite Stacker Box, 19 gal, Gray, Model#14765906). The great thing is that turned cross ways in the box makes a nice pathway to put the planned exterior door in the middle of the box.
I then used 1x2, liquid nails and screws to attach a couple of stops in the bottom of the box to hold the bins in place but with a simple lift and pull toward the center and they can be removed for cleaning.

Step 3: The Gangway

I used 1x10 for the gangway, 1x2, liquid nails and screws at either end to hold it up. I used Velcro on the ends to hold the gangway in place because I wanted it to be easy to remove when the bins needed to come out for cleaning. The Velcro seems to hold it in place very well. I covered the gangway with that 3M cat carpet to help keep the litter being brought back into the house to a minimum and help the cats with traction. I used 3M spray contact cement and staples to hold the cat carpet in place.

Step 4: The Passthrough From the House

I was very, very lucky here. Next to my back door there is a window so the studding below the window was less that the standard 16" apart.  They measured 10 5/8"  apart, which worked out perfectly for what I had planned. I used a large cat door from Cat Mate (model#221 white) on the inside of the house. I cut the hole, for the door, in the center between the two studs under the window and installed the door.  Next I used a reciprocating saw to cut the hole on the outside of the house all the way out to the studs on the top, bottom and sides. I used 1/2" plywood and screws to anchor it to the walls, floor and ceiling. I made the tunnel go out to where the box would be located, go through the box and fit slightly inside the box. Trimmed out, caulked and painted the tunnel to protect it from the weather.

Step 5: Connecting the Box to the Tunnel

Next I moved the box back up against the tunnel and marked where the hole needed to be for the tunnel to go into the box. I used the reciprocating saw again to cut the hole in the box. Next I moved the box into its intended spot so the tunnel was just protruding through the box and gave me enough to caulk around then screwed the box down to the porch floor. I caulked around the tunnel to keep the weather out because I may need to heat it later in the winter. Not sure about that yet.

Step 6: The Exterior Cat Door

Next I installed a Cat Mate (model#221 brown) cat door in the front of the litter box so my cats can out onto the screened in porch when we're home and enjoy the great outdoors watching all the birds at the bird feeders.

Step 7: The Final Touch

I installed two battery powered LED lights that work on a motion sensor so the cats don't have to negotiate the box in total darkness. There are several makes and models out there. You are welcome to choose your own.

Thank you very much for viewing. I hope this is helpful and inspiring. Questions and comments are welcome.




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    I've been considering doing this for a bit not realizing it had already been done. Glad to have come across your instructable as it will save me some time figuring out how to get it done. Thanks!

    This is fantastic. Just moved into a new house with one problem... No good place for the litter box! Gonna try this with a cat door window insert and elevate the box. Question: have you ever had any issues with pests/bugs getting in the box? Is it water tight? Think it could get rained on and be okay?

    1 reply

    No, I have not had any issues with any bugs or pests. The deck box I used I would say is water tight so you shouldn't worry about exposing it to the rain.

    Hi there! Nice ideas! But I wanted to ask you, that after a year, how has it worked out for you? Do the cats like and use the the enclosure? My new apt is small but does have a decent size porch. Thinking of moving my cats' litter boxes out there. Would appreciate your input. Thanks.

    1 reply


    Its been working out fine. The true winner is the use of the Blue Buffalo crushed walnut litter. It is more expensive but it is completely oder free, so intern, worth every penny. At first, using clay litter alone in the summer made the porch unusable by humans and the smell would leak through the cat door into the house making the den smelly too. My GF has one cat (Homer) that when he first moved in, didn't like the Blue Buffalo crushed walnut litter by its self. So we mixed a little clay onto it to appease him and that worked. This summer we're planning to cut back in steps back to straight Blue Buffalo again and hopefully he will now be fine.

    The humid heat here in southeastern Virginia requires cleaning the litter box in the summer twice a day regardless of what litter you use but it not that dirty so it cleans very quickly and easily. Between keeping the box clean and the Blue Buffalo, there is no oder at all. We've had guests on our porch who had no idea what the box was because there was no smell.

    I hope this helps.

    Brilliant, absolutely brilliant. I love the front cat door for them to enjoy the screened in porch as well! :) It's nice to see a man who makes things work out when their lady is an animal lover. Kudos to you!

    I LOVE it, thanks for sharing!! I am always looking for more ideas, I am so happy that you made a way to keep all four cats. Smile. In the winter...merely a light bulb could keep it warm enough to be comfortable and maybe some insulation perhaps?

    Amazing! I was curious where you got the 3M liter catch pad? I have been looking for a better alternative to my plain-ol' rug. Bill likes to track liter all over his room. Thanks, and again this was an amazing idea.

    1 reply

    Thanks so much for your kind words and you are very welcome.

    I found the 3M litter trap mat on Amazon. Here is the link. <http://amzn.com/B006T7MMC2> > It is 18"x 24". If you need one that is bigger, there is another one from Scotch that measures 24"x36" <http://amzn.com/B00GYR0DLO> > Amazon Prime for the win! They are both actually made by Pruven so they are the same product, just packaged and sold by 3M and Scotch.

    Great idea

    Tooooo great. Great idea to eliminate the mess and odor from a multiple cat household. I have a nearly enclosed covered patio attached to a sunroom that already has a pet door remaining from previous owners. You have inspired me to finally complete the enclosure AND rid my home of catbox mess! Added plus is Kitties can be "outside"! Thanks for this Instructable.

    1 reply

    You are very welcome! Cutting a hole in my house was scary. You know how things can just not go as you plan. Measure twice and cut once kinda thing and hope the cats will use it. I hope your project works out as nicely as mine did.

    Way cool. I hope the cats like it. If they've had open top boxes before, you may want to transition them with the top lifted until they are using it without incident. If they've all had covered boxes, they'll probably love it as long as they can find it. Nice job.

    1 reply

    Thanks very much!

    As matter of fact, I only adopted my girls in October when I bought the house and moved in. I started them out with a top entry litter box I made from a storage bin similar to what I used in this project. My two girls love it! They love the fact that they can go outside onto the porch. The younger one took to the cat doors almost immediately. The other took a couple of days. She was a bit freaked out by the flapping motion of the doors. she would go through it so slow that the door would flap back onto her tail. It made me giggle in a sadistic kinda way.

    Wow.... This idea has lifted a funk completely about my Bf moving in with me. He has 2 cats and I have 0 pets. I also work from home and know that I would be dealing with the cleanliness of these cats inside my home. We'll I had alittle attitude about him not having to deal with it has much considering they were his cats. This idea is my solution...that way when he gets home he can do kitty liter and I will do vacuuming and feeding inside home.... Thank you so much!!!!

    1 reply

    You are very welcome! I will tell you that the hardest part was making the commitment to cut a hole in my house. If I ever want to sell my home only cat lovers will want to buy it.

    With just my two cats now, I only have to clean the litter box every other day. I'm sure when my GF moves in it will go back to every day, I'm sure. With the litter genie I have, it only takes a few minutes to clean both boxes. Its kinda funny too, they seem to do only #1 in one box and #2 in the other.