Simply assemble a three-sided wall of logs on each creek side -with the open end stuck in the bank -sort of as if you were making a little log cabin (Fig. If your banks taper too gradually down to the stream for that “best case” solution -or if your span’s a bit longer than you’d like -you can build out or up from the sides of the stream bed using crib construction. That way, you’ll have to “ramp” up slightly to the bridge itself, which will help the structure shed rainwater. And try to design all this in such a way that the logs end up a little bit above ground height. Or, if you don’t have the rocks, you can pour cement for these “footings”. Then lay some good-sized -say, 6″-thick -flat rocks in the troughs and set your stringers on those (Fig. In such a case, dig ditches about four feet long into both sides of the bank to receive your logs. ![]() Ideally, you’ll have steep banks that rise well above the stream you’re crossing and are close enough to each other to give you an acceptably short span. The design of the foundation on which you put your main bridge logs, or stringers, will depend on where you’re building. (If you bevel the underside of each log a bit first, though, the log will have less tendency to jam in the ground when you’re pulling it.) Then you’ll be ready to prepare a resting place for those timbers. Once you’ve cut the best and straightest logs you can find -they should also be at least a foot in diameter (not counting the bark) and have no knots in their middle halves -you can haul them to your bridge site. However, if you’re stuck using alder, ash, aspen, beech, birch, buckeye, butternut, cottonwood, elm, hemlock, hickory, magnolia, maple, red or black oak, most pines, poplars, spruces, sweet gum, or true firs, you’d best inspect your bridge logs often! You say you don’t have any of those? Well, bald cypress (young growth), Douglas fir, honey locust, western larch, swamp chestnut oak, eastern white, longleaf and slash pines, and tamarack are all moderately durable. Bald cypress (old growth), Arizona cypress, catalpa, cedar, chestnut, juniper, mesquite, several of the oaks (bur, chestnut, gambel, Oregon white, post, and white), redwood, Osage orange, and Pacific yew are all quite decay-resistant (especially the last two). But plenty of other woods -assuming they’ve got more heartwood then sapwood -can do the job. Around these parts, folks generally use the amazingly durable black locust. ![]() Of course, you’ll need some logs, as well. You’ll also need a helper with a stout back (bridge building is definitely a two-person job). ![]() (Mind you, there are a few extra touches and tricks of the trade we’ll be telling you about.) The main tools you’ll need are equally basic: a tractor or pickup truck with a chain for pulling logs… a chain saw… an ax… a bark peeler and adz (if you don’t have these, you can use your ax instead)… a chalk line… a level… a couple of scrap 1 X 8’s or similar boards… some roofing cement… a shovel… a couple of peaveys… and a heavy hammer (see Fig. Step two: Lay some stringer logs across the span. Step one: Build a good base on each side of your waterway. So if you start to drive the front wheels of an extremely heavy vehicle over your stream-spanner and you hear something begin to crack… BACK UP QUICK! Main Tools and StepsĪn untrussed bridge is simplicity itself. But let’s get one thing clear right now: We don’t guarantee that any bridge you build will bear up to a load like a concrete truck. In doing so, we’ll call upon wisdom gleaned from Rick’s considerable experience, and all the relevant research and calculations we could muster. ![]() A simple,”no suspension or trusses just lay down some logs and flooring” bridge… the kind of farmstead structure that’s intended for getting you over drainage ditches or small streams. We’re going to tell you everything we can about how to build a log bridge. Pretty impressive, huh? Well, don’t let Compton’s success go to your head. And if you’re curious to see what took place when we did drive one of those massive vehicles over Rick’s completed structure, see the Image Gallery. That was Rick Compton’s wager about the 14-foot log bridge he and Hoy Gross were finishing out at the MOTHER EARTH NEWS Ecovillage. I’d just about bet my little pickup against a pocketknife that this thing’ll hold up a cement truck.”
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |