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Welcome to Dunton Family Farms
Since 1909

Constructing Our Solar Composting Toilet
"Building 33"

[ Project Summary ] [ Design Features ]
Operating & Maintenance Information ]

This is one of those important projects that took a long time to reach the top of the project list. It is too inconvenient to be working in the barnyard or fields and run up to the house whenever the situation arises. Additionally, we were just not set up to accommodate visitors. Our goal is to eventually open the farm to the public and now we have a toilet facility.

We had this project listed on the Victory Seed Web site in 2004 as a future need. A gentleman up in Washington, Larry Warnberg, responded by supplying us with drawn plans for two composting toilet designs he had engineered and put into use. Included in the package he sent were instructions and actual observations he had documented while operating one. He also generously donated a copy of the poop bible, "The Humanure Handbook."

Although he sold copies of his plans, he retired and moved on. If you are interested in building and experimenting with one of these alternatives to flushing, along with the information presented here, you can also reference an archived copy of his web site by clicking here. It is a great idea for an environmentally sound way of eliminating waste.

My goal was to use Mr. Warnberg's design ideas but build the facility as inexpensively and with as much recycled (scrounged) materials as possible. This meant that improvisation and adaptation were required throughout the project.

Additionally, this project was intended to expose John to basic building skills. Although I performed most of the work, I made sure to explain all of the steps, solicited his input for ideas, made sure he understood the various steps, and actually had him do hands-on work. The following is written in journal format as the project progressed.

This was the initial purchase. It is a 54 gallon (204 liter) Rubbermaid tote and cost $16.97 at the Home Depot. The design hinges on the size of the chamber you will use. We plan on using two such bins in rotation.

This is part of our scrap lumber pile. The main source was cedar boards from the old yard fence and pallets from the concrete fence shipment.

 Salvaged shakes.
(NOTE: Did not end up using them in this project.)

 More of the lumber pile. Mainly 6 foot cedar fence boards.

 Two of the pallets positioned roughly in place.

Working on the floor and foundation.

Working on the floor and foundation.

Sub-floor done and rough leveling completed. John modeling the approximate location of the the bench.

Guarding our tool cart :)

6/19/2006 - The first day of work we got the site cleared, the main platform built, and it situated roughly in position.

6/20/06 - We did not get much time at all to dedicate to the project today. More pressing business and farming tasks required our attention. We did get the platform situated in its final location, leveled ground for pier blocks and started the process of leveling the floor itself. We worked until after dark.

John was gone the next two days and then we were off to California for five days. Pressure to get this facility completed by Independence Day are building.

6/27/06 - I was pretty sure that we had worked on this project since last week but we have not.

John and I determined the outhouse's name today - "Building 33." That will be our code for heading to the outhouse. Where this comes from is the door. The door was salvaged from an apartment complex remodel project many years ago and it happened to be from unit 33. That is the number on it. John said we should renumber it #2.

Anyway, since we are using salvage and scrap "stuff" to build this, we are kind of designing and building this as we go. It makes it a bit of a slow go but I think we finally have it pretty well figured out and have made some headway.

Today we started by leveling, cutting and setting all of the posts onto the pier blocks. That actually took a couple of hours. Then we started scrounging through the loafing barn, hay barn, and machine shed for 2 x 4s. Rounded up enough to start framing the walls. Got the studs cut and notched for the north and south walls and actually got the south wall erected and tacked down. The north wall got framed but we ran out of light. Left everything out so hoping to get to it in the morning.

Close-up of the foundation work.

John cutting boards to keep me going. Having a helper really makes work like this easier. His dogs are never too far from him.

North wall completed. Since we are using old 6' fence boards, had to use Z-flashing. Dad ran to town for me to get it and two bags of nails.

Back view looking into the northwest corner.

Front view. Temporary step built. The door is just propped in the opening to test it. Need to buy hinges tomorrow.

Back view looking into the southwest corner.

6/28/06 - We got quite a bit done today. You can read the captions for the details. The farther I get into the process, the more nervous I get that the toilet is too shaded and will not get the solar energy necessary for proper functioning. Hopefully the fear is unfounded.

Business end view of the composting chamber. The sheathing material is 1/4 inch Plexiglas salvaged from a skylight replacement job a friend did.

Back panel and lid installed. The front panel is removable (see figure 5) for ease of access.

Lid in closed position. We still need to cut and install the side panels.

Figure 4 - Close-up of fasteners. These were left over, self-sealing metal screws from doing the cabin roof years ago.

Figure 5 - Close-up view of front panel back. The panel is removable using drilled holes and concrete nails as the pegs.

Lid in open position.

Close-up of drip flashing and lid hinge. I will install a flexible piece of rubber over the lid top.
Door hung and hardware installed.

7/5/06 - I was not able to dedicate much time to this project between the last entry and now. Sunday, John and I got the back end (the composting chamber) designed and framed. We also got the door hung and adjusted as well as the knob and latch hardware installed.

Monday (the third) we worked for about four hours. We got the back boards and bats on and cut and installed the Plexiglas panels on the composting chamber. Since we do not have cedar lumber long enough for bats on the two side walls, we used what we had and pieced together enough to seal up the cracks from the inside for privacy. However, this was a wasted step as we were a long way from actually putting it into use.

Since it was getting late and our company was due to arrive, we called it quits and cleaned up the yard. We have worked a total of about five afternoons on this project. Perhaps five more and it will be fully operational. We will get back to finish it soon.

7/12/06 - Between an elbow injury, a back injury and the holiday, we have not gotten anything done on the toilet in days.

Today, John got the old corral fence torn down and I gave Dad a lumber list to pick up tomorrow at Home Depot. Of all of the salvaged lumber I have on hand, I do not have any long pressure treated 2 x 4s. Hopefully we will get the new fence up tomorrow. Feels naked with the old corral fence gone.

7/13/06 - We worked until dark, taking time to patch up some torn up tin on the loafing barn, built the new fence structure, and started hanging the fence boards. Like everything around here, it takes longer than it sounds because we are designing and problem solving as we go along.

Privacy Fence Completed

View From Below

View from the Bottom Field

Installing the rafters

Roof at Night


Inside of the Door


7/15/06 - Today we got the privacy fence completely built. This is all from wood that we salvaged from the state imposed fence removal last year. It is all pretty sound cedar lumber but is weathered and makes the fence looks like it has been there for years. I like that. Prefer it to new looking.

Then we started to tackle the toilet roof. Finally working on the outhouse after a couple of weeks hiatus. Anyway, instead of a standard roof like on the cabin, I wanted to top the structure with a pyramid. Initially I wanted the pyramid to be composed of four perfect triangles. This posed a problem that took hours of digging through carpentry and math textbooks, searching the internet, and trying to remember geometry and trigonometry. It was the exact angle of the compound miter cuts that I was seeking.

Anyway, I ended up realizing that a pyramid can be created from any four, equally sized, isosceles triangles (as long as the height is greater than one-half the length of the triangle's base).

So after a couple of hours of thinking, research, trial and error, and failure, I threw the boards on the ground, made the top angles 45's, and called it good. After getting the rafters installed, I called it a day. Hopefully we will start on the roofing tomorrow. Oh, one point of interest -- the rafters are reused, nearly full dimensional, old Douglas Fir rafters from the old chicken coop. The picture to the right is looking up at the bottom of the roof's peak from inside the house.

9/6/06 - After a month and a half, I am finally carving out a bit of time to work on this project. About three weeks ago (August 12) John, Dad and I went to Lynn and also Joni and Jim's house and scrounged a huge pile of lumber. Lynn's was free and I gave Jim $200 for his. I got some cedar boards that John and I milled and planed to make the remaining bats for the siding. We got those nailed up and then went back to work on the equipment shed project.

Yesterday I started working on the outhouse roof. I can feel the rainy weather season bearing down on me so I moving fast. Today we got the sheathing up which I will cover in roll composition roofing (leftover from building the chicken coop years ago). Then we pressure washed the last four panels of salvaged Plexiglas sheets that will be formed into the skylight. Once I get the roof on, I will be able to breath a bit easier and come back to the interior as soon as I get the equipment shed done.

Cardboard Template

Thickness of the Plexiglas


Panels Cut

9/7/06 - We secured the plywood sheathing and added some blocking. Then started working on the skylight. Since John was not home, I didn't want to do anything too crazy on the top of a ladder or roof so I had to rethink how I was going to cut the heavy sheets of plastic.

The sheets were 1/4" x 4' x 5' and pretty heavy. Throw in a bit of wind and the top of an 8' ladder . . . I do not bounce like I did when I was twenty. So I hunted and found a big chunk of cardboard and used that to make a template. I then used the template to cut the four panels of the pyramid.

John cutting roofing.

9/8/06 - We continued working on the roof. Before I could get started, had to mill pieces to to sit on top of the rafters so that the skylight pieces would be on the same plain as the composition. Got the tar paper nailed off and while John cut out the roofing, I would goop up the roof with tar and install a piece.

Insulating the back (east) wall.

John cutting boards for the walls.

Solar composting chamber complete

Back (east) wall.
View of the skylight from the inside looking up at night.

9/9/06 - Got a bit more done today. Caulked all of the cracks to make the room insect resistant. Cut the last piece for the solar chamber and got it all completed except for weather stripping. Scrounged all of the tubes of caulk I could to install the skylight panels but we were short so will have to install one panel tomorrow. So we shifted gears, insulated the back (east) wall and installed the wall boards. Getting closer! Should be able to get the bench installed tomorrow.

South & Back Walls

North & Back Walls

Front & South Walls

Our little outhouse in the trees
Showing perspective to where the toilet lives in relation to the cabin.

9/10/06 - We moved a few steps closer to completing another project today. It is really hard for me because I want to start on the machine shed / pump house so I can get that buttoned up before the rain really starts.

Today we got the roof done and I caulked the heck out of it and any little cracks. Finished odds and end flashing, weather-stripping, and made and installed a vent stack. Basically worked at getting the outside of the building all completed. And we did.

We did have to head into town to the hardware store to pick up some caulk, a piece of flashing for the roof ridges, a toilet paper holder, a top for the vent stack, and an ABS "L" fitting.

We now have about $50.00 into it! Recycle and reuse has been the key. Tomorrow I will focus on the interior.


Looking down on the bench.

Looking up towards the perimeter shelf.
Window trimmed including shelf.

9/16/06 - Most every day this week, except for Thursday (I think as it was rainy), we got a couple of hours on the project. Today we came very close to finishing.

At about 4:00 p.m., John and I both got to work on the toilet. Finished the wall boards. Trimmed out the door and the window. Build a shelf for a window sill. Built a shelf all around the inside perimeter at the top of the wall. Washed the window and door. Finished framing the bench and just before dark, got the plywood cut. Famous last words, but I think we can finish tomorrow.

Painting Floor


Bench and floor painted.

9/17/06 - About 4:00, I started working on the toilet.

I got the hole cut in the bench and the the next problem that needed to be solved was how to get the seat is sit tight against the bench and the lid tight on the seat. I took the seat apart and mounted the hinges on the top of the lid. Then I used some 3/8″ flooring to create a shim of sorts that will allow the hinges to work but keep the seat lying flush on the bench. The goal was to create a seal so that odors do not vent into the room and can head on up the stack in the solar chamber.

I then used the floor paint that was left over from the cabin to seal up the underside of the bench, the front of the bench, and then I mounted the top to the bench and painted it.

After supper, I got the floor screwed down and painted. Then we cleaned up and it was about dark.

Photovoltaic panel and integrated charger. It contains and maintains four AA-sized batteries.

The system had an on/off switch on the body of the lamp but since it is ceiling mounted, that was not practical. I tore the lamp apart (a 6W florescent) and wired up a "remote" switch. I made a mounting bracket for the switch and mounted it in a standard location.

Here is a shot of the complete interior portion of the system. I had Dad pick this up at a local tool liquidator a few months ago. Regular price is $39.99 but I got in on sale for about $30.00.

9/18/06 - Today the forecast was rain, and in the morning it looked like ark sailing weather. But it the afternoon it dried up, got warm, and actually got sunny. So out to the toilet to work I went.

It was a puttering day. Had a cold beverage, gained some patience, and started dismantling the brand new solar lighting system I got. Rewired it per my needs (see below) drilled the necessary hole in the building, and got it operational.

Click Here for the Solar Light Manual (PDF)

That done, I set to finishing up little loose ends. Hung a couple of things on the wall. The Picture frame of rock slabs (looks like a butterfly, it one my Great-grandpa Schoenborn made me in 1979.

The geodesic patterned hooked rug handing on the wall behind the toilet was made for me in the mid-70s by my Uncle John L. Dunton, Jr. It is an original design and he told me that out of the dozens he made back then, he thinks that I might be the only one to have hung onto it. Anyway, its colors look great in this room.

Additionally, I used a chunk of roofing paper to make a pee splash guard at the front of the toilet, installed some toilet paper in the holder, threw down a rug, installed the toilet seat, and broke it in. It is now officially open for business.

Interior shot. Seat up for illustration purposes. It is intended to remain down when not in use.

Inside view of the composting toilet

Click the picture to see inside . . . if you dare!

Project Summary:

This composting toilet was completed with a minimum amount of cost (less than $100 including the solar lighting system) and about 60 hours of time. It turned out to be an attractive and welcoming structure that is completely self-contained. This includes passive solar lighting from the skylight and the screened window during the daylight hours and photovoltaic derived electric lighting at night.

Its key design features include:

  • Portability - Although our design is heavier than Mr. Warnberg's, we could easily use the forks on our IH-606D tractor to pickup and relocate the building.

  • No Electric Hook-up Required - As mentioned, passive solar is used and optionally the photovoltaic system is used. Passive solar heat is used to heat the composting chamber and create convection currents for ventilation.

  • No Foul Odors - Unlike the pit toilets people think about when they hear the word "outhouse", this composting design is an aerobic process in which microorganisms and earthworms convert the organic material into a safe and valuable soil amendment. The by-products of the process are heat, water vapor, and carbon dioxide.

  • Environmentally Safe - Again, this is a completely self contained facility like a "porta-poti" but differing in that it actively and efficiently processes the organic material. There is no leachate to contaminate waters. Pathogens are destroyed by the heat generated by the thermophilic composting and aging.

  • Low Maintenance - The interior in no more difficult to clean and maintain than a standard bathroom in your house. Cleaning the composting chamber will depend on the amount of use it receives. We will report our results on the operating information page.

Again, if you are interested in learning more and purchasing plans and an informational kit (very worthwhile and reasonably priced), contact Larry Warnberg through his web site at:


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