The Outside Bathroom

Summer.  

Hot days, pool parties, and kids stomping through the house.

Ah, about that last thing... first there was the guest's seven year old who was left to use the bathroom unsupervised.  He peed all over the floor and Mama Monkey had to clean it up.  Then there were the trio of girls that decided to give themselves a house tour.  We found them poking at our parakeets through the bars of their cage.  And of course there were the occasions of sunscreen smeared on the cabinets, sticky thighs taking a break on our suede sectional, and numerous instances of dripping pool water on the carpets on the way to the facilities.

For the last few years, Mama Monkey and I have shared a running joke:

The Outside Bathroom.

How splendid, we imagined, would it be if we could conjure up a bathroom for the exclusive use of our backyard guests?  Then we could host gatherings as often as we pleased, but keep the back doors locked up--as tight as the overstretched skin on the cheeks of an aging Hollywood actress--keeping the party outside!

This year, we really gave it some serious thought, and realized... well..  why not?

We being us, this couldn't be just a hole in the ground or a composting toilet or anything else gross like that.  While I jokingly referred to the project as the Outhouse, it always had to be the real deal--full flushing toilet, porcelain sink, and running water.  Time was short, however, as I only had one month of weekends to build it.


The plan was to build a small standalone building from the ground up, and tuck it beside the side entrance to our garage.  I wanted to use the same stucco-textured Hardie Panel concrete siding boards that I used for the barbecue islands last summer.  Since they come in 4x8 sheets, a 4x4 building would be ideal, and just large enough to comfortably fit a toilet and small sink.

Conveniently, the drainage could run to a nearby sewer cleanout at the side of the house, so I started by building an elevated platform built with pressure treated lumber.  The raised floor height would allow space for piping below the toilet and provide the proper 1/4"-per-ft. down slope to the cleanout.

Above the platform, I framed the structure with 2x4 and 2x2 lumber, keeping the side walls half normal thickness to maximize the inside space.  The front would need to be full depth, however, as I would have to frame and hang a door inside of it.




With the walls open, I roughed in the plumbing and electrical.  I used armored cable to wire up a combination light and vent fan, connecting them and a switch to an AC power inlet jack so the bathroom could be powered by an extension cord.

I connected water supply lines to an RV-style garden hose water inlet connector.  For waste venting, I ran a pipe up and out the back wall, topping it with a custom vent cap I designed and printed on my 3D printer.

With those two items complete, I insulated the walls with rigid foam to keep out some of the summer heat.


The stucco-textured Hardie Panel made easy work of the exterior.  They screwed right on with self-tapping screws.  Then, add a little paint applied by some industrious volunteers and presto! a perfect match for the house.

The only puzzling dilemma was how to finish the exposed panel edges at the corners.  In the end, I ripped PVC rain gutters to make inexpensive waterproof L-channel trim: functional, yet a fraction of the cost of raw PVC angle material.

For the roof, I chose a simple slanted shed roof with Ondura Fiber/Asphalt Roofing Panels mounted to a 1x6 frame.  To avoid penetrations in the surface, I routed the output of the exhaust fan to vent holes under the eaves,

One of the benefits of having only sixteen square feet is that one can afford to splurge a bit on finishes.

We chose materials to keep the bathroom water resistant, including FRP (fiberglass reinforced plastic) walls, and PVC wainscoting, baseboards, crown molding, and trim.

For flooring, we chose a nice porcelain floor tile, and set a single box with crack-resistant thinset and waterproof flexible urethane grout.

Finding a proper sink proved to be a challenge, but a tiny pedestal sink from Signature Hardware fit perfectly.  To hold the sink, I fabricated an aluminum bracket with threaded posts and imbedded it in the wall before skinning it.  The finished floor height ended up being about 3/4" lower than estimated, but I was able to compensate for the difference using my 3D printer to fabricate an extra spacer ring to fit between the sink and pedestal.

After five weekends of planning and construction, finally, here is the completed bathroom.  During construction, the floor platform rested on temporary casters so the bathroom could be pulled out to access all sides.  After completion, it was simply rolled back into place.

The unit it technically portable, since the sewage line connects with hose clamps, power is plugged in, and water comes from a garden hose.  The floor platform is even purposefully open in front and sized to fit a forklift or manual forklift cart. 

However, it currently works splendidly well where it is.  It has proven to be super convenient and a big hit with both guests and family.

Next, up, the pizza oven!