Our photographer, Tom Fenenga (he’s the one with the striped shirt and big grin), is very involved with his son Adam’s Boy Scout troop. Tom wanted to teach the scouts about construction, and they needed benches around the fire pit at the scout camp they visit each year. So we came up with this design. They’re simple enough for teenage boys to build, tough enough to handle their roughhousing and economical enough at less than $100 each. You could build one in a Saturday.
We decided treated wood was a must—along with exterior 3-in. deck screws rated for treated wood. And the benches had to be embedded in concrete in the ground to keep them from being “relocated.”
Screw the parts together with two 3-in. deck screws at each joint. Draw guidelines alongside the 4x4s to use for the other set of legs. Center the base piece and make the seat support flush with the top of the front 4x4 and square to the back one. Flip the assembly over and screw the second base piece and seat support onto the other side of the legs.
Start by cutting all the parts to length, following Figure A and Photos 1 and 2. Then pre-assemble the legs with screws. You can do this in your shop or garage where you have a flat surface.
Place a plywood scrap under the first set of legs and position the 4x4s following the measurements in Photo 1. Outline those positions so you can use them as a pattern for the other set of legs to be sure they match perfectly. Keep the screws away from the center of the 4x4 so you don’t hit them when you drill holes for the carriage bolts.
Drill and bolt together the seat supports and 4x4s. You can buy a special 1/2-in.-dia. x 12-in.-long spade bit or extend a standard-length spade bit with a magnetic bit holder (Photo 2).
Set the legs on a level surface, spacing them 4 ft. apart, and temporarily brace both ends of the base pieces and the front of the seat supports with 2x4s (Photo 3). That'll hold everything together with the proper spacing while you attach the seat and back boards. Once they're screwed on, remove the braces.
Evenly space the seat boards from the edges of the seat supports and screw them to both seat supports with 3-in. deck screws: two screws into each support for the 2x4s and three for the 2x10s. Place a carpenter’s pencil between the boards to space them (Photo 4). Flip the bench upside down, center the back supports and attach them with 3-in. screws (Photo 5). Run those in at an angle so the tips won’t penetrate the seat and back (or your seat or back).
Position and mark the trenches and dig them about 8 in. deep. Rest the bench in the trenches. Check the bench for level and height, then remove it and adjust the soil levels as necessary. Pour 1-1/2 bags of concrete mix beside, between and over each base and cover with soil. Pour a couple of gallons of water over the dry mix and backfill the trenches.
Set the bench exactly where you want it and outline the trenches around each base. Then set the bench aside and start digging (Photo 6). Your goal is to have a level bench with the seat about 15 in. above the ground at the front—the typical height for benches. But once you achieve that, just sit on the bench. You might want it lower, higher or reclined a bit more. Get it just the way you like it.
Then mix up three bags of concrete mix and pour half over each base, filling the space between and alongside. Throw any extra over the top. Then backfill the holes, wait a few hours, start the campfire and roast some hot dogs and marshmallows.