A Brief on Better Backhouse Building
from "Cottage Water Systems" by Max Burns (a Cottage Life book)
The following is a short guide to construction techniques for a traditional shed-roofed, one-hole pit privy with wood floor, 4 ft. wide x 4 ft. deep x 7 ft. tall (at the front). All dimensions - and the hole count - can be expanded to suit cottage requirements and the stylistic inclinations of the builder. Use 2 x 6s on edge for floor framing, and a 4 x 4 for the Lem Putt corner post; standard construction-grade 2 x 4s serve well for the remainder of the framing.
A distance of 7 ft. between the floor frame and the roof frame at the front and 6 ft. at the rear (making for a gentle slope of 3-in. rise in 12-in. run) provides adequate headroom for most cottagers, the lowest part of the roof being directly above the sitting area. However, professional basketball players may want to increase these dimensions.
Seat height (from the floor to the top of the lowered seat) should be between 12 in. and 16 in. (depending on family ergonomic preferences), the frame of the bench consisting of 2 x 4s on 16-in. centres front, top, and back. Keep the space directly above the hole wide open and clear of obstructions. I install the galvanized metal liner before nailing the top framing members in place; if you try to install it after the seat frame is built, you'll have to tip the outhouse on its side. Set the hole about 2 1/2 - 3 in. back from the front seat riser.
The 2x4 wall studs can be placed on 24 inch centres, tying in with the seat front. Headers are required at the top and bottom of the walls (such headers are called top and bottom plates) and above and below a window. A door needs a header only above it. Wall sheathing can be applied horizontally directly over the framing, but if vertical siding is to be used, the framing will need to be strapped (24 in. on centre) to provide sufficient nailing spots.
The roof should be approximately 68 in. square, leaving a 10-in. overhang at the sides, 9 in. at the rear, and 9 1/2 in. at the front. The roof frame is made from 2x4 rafters running front to back on edge, with single 1 x 6s at the front and back of the roof to act as headers. Sheathing can be plywood or 1 x whatever boards. If you want a skylight, use a sheet of Plexiglas 16 in. wide by whatever length seems reasonable (like 16 in. for a square skylight). This allows the skylight to sit over a 14 1/2-in. opening cut between the centre rafters with no addition- al framing needed. Install the Plexiglas (or similar plastic) as you would a shingle - that is, the bottom overlapping the shingles below, the upper edge be- ing overlapped by the shingles above, and screw it in place (pre-drilling the holes). Use silicone caulking to seal it to the shingles and to seal out the weather. Use rubber vent gaskets where the vent stacks penetrate the roof, incorporating them into the shingle pattern as well.
The easiest door to make is 1 x 4 or 1 x 6 ship-lap or tongue-and-groove boards butted together, with a Z-shaped support glued and screwed to the back, using 1 x 6 wood. A space of 1/8 to 1/4 in. between the door and its frame, and also between the two halves of the Dutch door (if used), allows the door to function without binding. Overlapping the frame of the lower section of a Dutch door with the lower bracing of the upper section by an inch or more will help keep the weather out.