A Modern Outhouse Among the Joshua Trees: Scott’s Off-Grid CF 4 Build

When Scott set out to build a bathroom for his off-grid tiny house in the Joshua Tree area of California, there was no sewer to connect to and no reason to dig a septic system among the trees. So the bathroom became its own small building a short walk from the house — and it turned out to be one of the most striking outhouses we have seen.

What he was after was simple enough: a toilet that looks and feels like an ordinary one, without the water — and no smell, ever. That is a tall order for an outdoor building in the desert, and it is the reason the system under the floor is a CF 4 composting toilet.

Scott documented the build from the first floor joists to the finished outhouse. Here is how it came together.

The setting: a tiny house in a Joshua tree forest

The property is about as far from a municipal sewer line as you can get: a small charred-wood tiny house surrounded by Joshua trees, with desert mountains on the horizon. Hot summers, cold nights, and the occasional winter snow.

Why a separate bathroom building works so well

A tiny house has no square footage to spare. Moving the toilet into its own building keeps the living space free, and it let the bathroom become a design piece in its own right — with wide openings looking straight out at the trees.

The reason it can look this good is the kind of toilet underneath it. The CF 4 is a split system: the only thing inside the room is an ordinary-looking porcelain pedestal. The composting unit sits below the floor, and waste drops straight down a short chute into it. No plastic cabinet, no bucket, no visible hardware.

Step one: put the composting unit in before the floor

With a below-floor system, the order of work matters. Scott set the floor frame on concrete pier blocks and placed the CF 4 container before a single floorboard went down, so the pedestal above could line up for a straight vertical drop into the unit.

How much space the CF 4 needs under the floor

The CF 4 container is 45″ long, 30″ wide and 29″ tall. That height is the number that decides most outhouse designs, and the CF 4 has a way around it: the unit can be partly buried. Half-buried, it needs only 13 inches of clearance below the floor. Sitting fully on the ground, it needs 29 inches.

Scott set the container about 15 inches into the ground, which kept the outhouse low and the deck steps short.

Venting and drainage: the two things that keep it odorless

Walk around the back of the outhouse and you can see the whole system working.

The vent stack. A vent pipe runs from the top of the composting unit up the back wall to above the roofline. Air is drawn down through the toilet and out of the stack, so any odor leaves the building instead of entering it. The CF 4 kit includes a 12V fan with a mains plug — and here, with no grid to plug into, the fan runs on solar. Our Solar Power Bank Kit has a built-in battery, so the fan keeps running through the night and through a cloudy day. A wind-driven Whirlybird on top of the stack is the other option for off-grid sites.

The drain. Inside the CF 4, waste lands on a false floor. Much of the liquid is absorbed by the compost and evaporates through the ventilation; any excess passes through the false floor and drains out of the bottom of the unit. From there it can go to a separate tank or, where local rules allow, to a dispersal trench — which is what the white pipe in the gravel-lined trench is for.

Inside: a porcelain toilet with a view

Inside, there is a white porcelain pedestal on a composite deck floor and two wide openings looking out over the Joshua trees and the mountains. That is all. You use it like any other toilet — toilet paper goes straight in — and add about a cup of dry covering material, such as hemp, after each bowel movement.

The finishing touches

Reclaimed boards on the walls, a charred-wood ceiling, a sliding black barn door and wide stepped decking. Outside the door, an outdoor vanity with a copper basin and an ornate mirror that reflects the Joshua trees back at you. It is a bathroom people will want to photograph — which, in this case, is exactly what happened.

What living with a CF 4 involves

The CF 4 is a single-chamber system. Fresh material lands at one end of the unit and older, composted material is gradually moved toward the hatch at the other end. Depending on use, you service it one to three times a year: rake the pile forward a little and shovel some finished compost out from the front. Because the liquids are separated from the solids, the compost does not smell.

Composting time depends heavily on climate. As a rule, allow at least six months before using the finished compost around trees or shrubs, and up to twelve months in cold-winter climates — and always follow your county and state rules for disposal.

If shoveling compost does not appeal, a swappable-container system such as the GL 90 fits the same kind of outhouse with a different routine. For bigger groups or public use, the CF 8 is the same design at about 250 gallons.

Planning an outhouse of your own?

Every site is different: how many people, how often, whether there is space below the floor, whether there is power. Answer a few quick questions and we will point you to the systems that fit — or read our full guide to composting toilets for outhouses.

All photos by Scott, used with permission. Our thanks to Scott for sharing the build.