Making a composting toilet – Deciding, then doing it.

(In no way is this webpage offering the final and absolute best way to do something.  I’m sure I made some goofs.  I’m sure it could be improved and it’s probably not how you’d do it.  This is good.  This is just my story about what I ended up doing, how I’d do it differently, and why I did it the way I did.  If you decide to use this information to make your own loo, more power to you, but it’s YOUR loo.  I won’t take any responsibility for it or any other activities you do because of something I might have said/implied/laughed about/intimated.  Life isn’t safe.  Don’t pretend it’s safe and don’t expect it to be.  Thanks and enjoy!)

This is a story about a woman on a very remote bit of land who got tired of outhouses and holes in the ground but still didn’t want to deal with septic systems (mostly because the ground’s rock hard and too difficult to dig much) or mess with plugged pipes and sewer snakes…  Never mind there isn’t public water service for a good 15 miles and a plumber charges by the hour to make a house visit – and the trip in takes a good 30 minutes if you don’t know where the bumps are…  So, she did a little web-searching, and found the Clivus Multrum toilets.  They were great, but the one she wanted was $5,000.

For a toilet.

No.

So she went searching again and found:

http://www.compostingtoilet.org

There were lots of different kinds of loos, but she (okay, I) was trying to get away from pooing into something where it would sit for years and maybe disappear someday.  I didn’t want to see it when I (or the rest of my family) went to err, take care of business, and I didn’t want to SMELL it either!  I didn’t want to have to go underneath and rotate heavy drums (or even buckets) full of poo, nor cap them for ‘curing’.  Forget it.  Give me something that sits out of sight and out of smell.  Something that maybe once every few months I go and poke with a stick to level out, but otherwise it handles itself.  Something that won’t stink.  Something that in a year will start to give me back something my ground and garden will love.  Yeah.  That’s my loo.

I decided to build myself a Clivus Minimus.  Well, my version of a Clivus Minimus.  I’m not an engineer, nor a genius.  I’ve got a degree in molecular biology so at least I’m a little educated about microbes and the disasters they can cause, so there are few worries there.  I printed out the relevant pages from the compostingtoilet site, headed off to the local hardware store, gathered my tools and dug in.

It wasn’t as difficult as I thought it would be.

These are the tools and supplies I ended up using:

In no particular order, there’s the:

Onward and Forward!

I’d done a lot of reading before starting to build, but I still didn’t have the actual measurements I‘d need, and some of the layout.  I cut out the sides first so they roughly matched the shape, if not the size of the info I’d seen at ct.org.   That started, I simply doodled on the one side until I got the innards lined up more or less where I thought they should be.  The floor of the poo-catcher is supposedly most effective at a 30 degree slope.  My hill has roughly a 20 degree slope where the loo will end up, so my catcher needed to be 10 degrees steeper than the back section of my floor.  Roughly, anyway.  The bottom three lines you see doodled are my various attempts to see where 30 degrees would end up on the back wall and in the front. I knew I needed enough room to get a small rake in to rake out compost underneath the catcher, but also wanted to leave enough room on top of the catcher for a goodly supply of, well, space for folk’s fresher business.  The box is about 3 feet wide, about 6 and a half feet long and about 4 feet tall from very bottom to very top. 

I assembled the floor, attached the walls and put the roof on.  Simpson angles screwed into the plywood bolster the sides and add holding power.  Greg says he wants a metal band added front to back just for structural security, but he hasn’t added it yet, so you won’t see it in the images.  I assembled it alone and it was tricky.  Things fell over repeatedly, my temper rose and it’s not until I wised up, putting a 2x4 between the walls that I managed to get the reinforcing screws in.  That’s also when I discovered that panel nails (which happened to be on hand from an earlier project) work great to hold plywood together, until those angles and screws could be fastened.  Y’gotta love panel nails.

Thing I would do differently: 

    

Next, I took the Henry’s (see above if you’re a visual learner) and used a pointed trowel to smear the inside of the walls with it.  I ran out before I was done and ended up having to get some more to finish.  I could probably just use bare plywood walls, but I want this baby to last and not rot out… so…

Things I would do differently: 

This is a detail picture of an inside corner.  You can kind of make out where I put the fiberglass tape at the bottom seams and partway up the side.  I put it wherever I thought liquid might be a problem for a little extra mental and liquid security.  Sealing things can be fun.  Use the trowel.  Henry’s dries in a day, less if it’s a thin layer and in direct sun.  You want to do your corners a little goopier than thin though, so it might take longer.

Did I mention I didn’t want the loo to rot out?  I went a little paranoid and decided that the loo should be lined with aluminum.  I couldn’t find big sheets of aluminum (where are they?), so I used rolls of 24 inch and 12 inch flashing.  It worked out pretty well, overall, although big sheets would have been more fun.  In this image I’m showing you how smart I was by putting the ‘upslope’ part of the flashing on top of the ‘downslope’ part.  That way, water can’t run under, or shouldn’t, anyway.

A scrap piece of plywood helped form the corners.  I’d bend them up against the plywood to start the bend, then put the metal and wood over the edge of the deck where I’d use a big honkin’ screwdriver to rub against the corner and help ‘firm up’ the bend.  Pinching with fingers was a very effective last resort if it just didn’t want to bend smoothly.  It’s not a good idea to bend it into an angle further than you ultimately want it to go.  It doesn’t much like unbending.

Here you can see the excellent job I did making a folded seam in the 24 inch flashing to make a wider sheet.  It’s running down the middle of the flat bit, then up the bent bit at the end. The first time I’d used a seamer. The sheet sounds like thunder whenever you move it. …had some fun with that!

That bent bit is angled to fit in the back of the loo as that corner is not 90 degrees.  I eyeballed it and didn’t get anal with actually measuring the angle.  Worked out great.

Things I would do differently:

Look Ma!  It fits!  Again, I’ve got the uphill flashing on top of the downhill.  I sure hope that liquid believes in gravity!

This is the front corner.  Look how nicely I measured!  It fit exactly.  Every now and then I really get it right.

…and sometimes I’m just plain bone-headed.  Wear gloves.  Aluminum will cut your hands before you even realize it.  I’ve got two or three really nice cuts here (one is fresh) all from aluminum.  Did I put my gloves on after this?  No.  Bonehead.  That’s me.  Yes.  I got more cuts.  No.  I haven’t learned.  Also, remember to wash your hands when you’re done for the day.  Ingestion of aluminum has been shown to decrease memory…  now what was I doing?

Things I would do differently:

Here she is fully lined and screwed down… but you’ll notice in the very back corner, about a third of the way up, the metal doesn’t fold sharply into the corner.  That’s because I started on the side nearest us in the image (thinking I was level) and when I got over to the other corner, discovered I wasn’t.  I’ll end up caulking it for a little extra security although it’s uphill of the deposit area, so I’m not real concerned about it.

Things I would do differently:

End by snipping and folding the edges of the sheeting over the sides for now.  The edge of the wood is good to be covered, but it can wait to trim out until later.  In the middle are two of my best friends.  Screw setter one and Screw setter two.

The middle folded seam was caulked next (peace of mind) then most of the back before I ran out of caulk.  I should have bought more and would list that as a ‘do better next time’ item, but I’ve already listed it above.  Just read it twice.  Get more than you think you’ll need. 

Greg gets me some white caulk later that night so I can finish up.  He buys more than he thinks I’ll need.  I end up using almost all of it.

Now we repair to the deck to make the poo-catcher.  I actually call it something else, but if I call it that here, Net Nanny might not let you visit.  It’s made out of æ” PVC pipe, primed and glued.  The plastic chicken wire is held on with plastic cable straps (nothing to rust out and be replaced here!)  I’m expecting the biggest load will be slightly off center and to the right, towards the back.  I’ve placed the bracing tighter in that quadrant.  I’d have done another round of bracing, but I ran out of T’s.  Get more than you think you’ll need.

Here’s the poo-catcher attached inside the loo, angled at roughly 30 degrees front to back.  I used 1 inch copper pipe straps to support it from the sides.  You can see some caulking.  The caulking smeared on the bottom is where I discovered that caulking takes longer to dry than Henry’s.  I ended up having to go over the caulking to some degree and it got messy.  There goes my ‘elegant’ caulking job.  Thankfully, I have learned to wear my ‘messy’ clothing when I do stuff like this.

Things I would do differently:

After the re-caulking job, you can see most of where the flashing overlapped itself.  Nothing’s getting behind this flashing!

These are my aerators.  They’re 2 inch PVC pipe, in which I’ve drilled a whole mess of holes.  They rest on the catcher at the bottom, and rise up above the catcher near where the loads will arrive, then through a 45 degree connector and up above where the pile will ever reach.  Their job is to keep the pile aerobic.  There will be a vent-with-fan pulling air through a screen at the front of the loo, through the pipes and out the aeration holes and up the vent.  Smell-combat 101.  It should also help keep the composting going strong and aerobic.

Here I’ve fully lined plywood with flashing to create a baffle.  The baffle’s job is to encourage air to go through the pipes whenever possible.  Yes, air could go underneath the baffle and up through the catcher, but how could I stop that?  I’m not sure I’d want to, would I?  The baffle is connected with simpson angles to the rest of the box.

I henry’d another piece of plywood of the right size and slipped it on top to make a support for the bottom access door.  For peace of mind (I’m getting a lot of that lately) I caulked the heck out of the connections.  (I also caulked the inside connection where the baffle meets the box.  I had the caulk after all and it sure couldn’t hurt.)

Then, I henry’d the doors.

and put them on, using old door hinges.  The screen is just placed for this picture.  Next trip up, I’ll trace that, cut it out and install it, maybe with a little raincover for the opening.  I’ll also put a bit of flexible vinyl flap over the hinged seam to help keep rainwater out (the front of the loo will probably be open to the outside for easy access, so a little extra protection is a good thing.) Foam weatherstripping on the underside of the door edge will keep flies and bugs out. I’ll probably also spiff it up with some paint for weather protection and snip, fold and screw down the metal edges so it looks attractive.

We’ll wait until the foundation’s done to pull it forward into its final place. Then the strawbale raising to install the floor above (but I might do up to the floor by myself just to get the loo up and running before the raising.  Wouldn’t that be nice?)  Get the vent pipe with little bitty solar-powered fan, deposit shaft, loo bowl and seat in place, spread a thick layer of pine shavings on the catcher, and we’re in business.  Extra-ready for the bale raising!

When all is said and done, I figure all the plywood, vents, parts and new tools (I had most of the tools already) cost about $250.  (not including solar panel as we’ll be plugging the vent fan into the yurt’s 12 volt when that gets up and running, so that’s not really a loo expense.)

I just ‘made’ $4750 with a few days work.

Somehow, that’s not what gives me the best feeling.  What I like most is figuring out and creating something that takes care of one of my family’s most primary needs – and building it all by myself!

Hooray!

 

Putting it all together

 

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