I found these instructions on how to build a garden bench on this garden furniture Leeds company’s website. The mourner’s bench is an inexpensive and durable bench to build for indoor or outdoor use. The origin of the mourner’s bench dates back to early 19th century evangelical camp meetings in Kentucky, according to “The Invitation: A Historical Survey” by Thomas H. Olbricht. The bench’s versatile style allows you to build a rustic piece made from rough-hewn lumber or create a polished finish from planed lumber. This 4-foot by 16-inch bench is portable and fits into most garden or deck schemes.
Decide whether to use rough-cut lumber or planed lumber from the store. Rough-cut lumber from a lumber mill accurately measures the lumber size. Lumber bought from the lumber company goes through a drying and plane process, shrinking the wood as much as 1/2 inch. For example, a 2-inch by 12-inch board shrinks to about 1 1/2-inches by 11 1/2 inches, and the surface is smoother.
Measure and cut one 4-foot board and two pieces 14 inches long. The 4-foot board makes the bench seat and the 14-inch pieces are the legs.
Follow the length of the 4-foot board from the end, and measure down the length 4 inches. At the 4-inch mark, draw a line horizontally from one side of the board to the other. Repeat this process at the other end of the board. The line marks where to align the legs later on.
Align one 14-inch leg horizontally along the line marked in Step 3. Nail into place (three nails across) and repeat the process at the other end of the board. The bench seat edges extend beyond the legs about 3 1/2 to 4 inches on both ends.
Rip the remaining board in half down the length of the board, creating a 2-inch by 6-inch board. This board goes under the bench seat between both legs as a brace for added support. It is not necessary to rip the board in two if you prefer the wider width.
Measure the length between the legs from the inside of one leg to the inside of the opposite leg. This measurement tells you how long to cut the support brace. Cut the board to the length obtained.
Turn the bench over on its seat and turn the support brace with one long side up. Insert the board between the legs to meet and butt the long side against the bottom of the seat, and the ends butted against the inside legs. Tap the board into place until centered with the center of the legs and bottom of the seat. Nail the board in place from outside the leg.