Design & DIY

What materials should I use when building the pit walls of my outhouse?

What materials should I use when building the pit walls of my outhouse?

I am building an outhouse and do not have a clear understanding of how to support the walls of the pit. Should I use 4″ block on a concrete footing or something else?
–Cliff Elliot, Parry Sound, Ont.

According to the Ontario Building Code (OBC), when building what’s technically called an earth pit privy, “The sides of the pit shall be reinforced so as to prevent collapse thereof.” Obviously you don’t want your outhouse, occupied or otherwise, to fall into a crumbling pit. However, the code doesn’t set out any specific materials you can or can’t use on the job. According to Alex Campbell, an on-site waste management specialist with R.J. Burnside and associates in Orangeville, Ont., “anything goes, just use whatever’s available.”

Campbell has supported outhouse pits with everything from pressure-treated fence boards to pieces of sheet metal. These can be driven down the sides during excavation. Loosely stacked concrete blocks will also do the trick. Sheet metal is particularly useful for holding back sandy soil.

Whatever you use, the area around the top of the pit should slope away from the opening to keep rain and snowmelt from flowing in. And although the bottom of the pit should remain open to allow liquid to seep out, it must also be at least 90 cm above the high groundwater table, as required by the OBC.