Square lashing

The wrapping turns run alternately over the crossbar and around behind the upright. This presses the two poles against each other at the crossing. On their own, though, these wraps would still have some play. So the frapping turns run between the poles, around all the wraps, and pull them together – making them tighter than you could pull them by hand.

What stops the poles twisting is mainly friction: between the two pieces of wood, and between cord and wood. The tighter everything sits, the greater the friction. The two clove hitches at the start and end only hold the cord ends; the real work is done by the wrapping and frapping turns.

A tidy square lashing looks neat: the wrapping turns lie close beside each other without crossing – outside on the crossbar, inside on the upright. The frapping turns lie tight between the poles and visibly squeeze the wraps together. When you shake the poles, nothing should twist or shift at the crossing.

You get the cord tight by pulling it up after each round before laying the next. A toggle with a marlinspike hitch helps you pull thin cord hard. Secure the cord end at the finish so it cannot come undone by itself, and do not leave it dangling loose.

The most common mistakes: wrapped too loosely, frapping turns forgotten, turns crossed instead of laid side by side, or thick, stiff cord that cannot be pulled tight. A loose lashing lets the poles tilt and twist – the whole frame becomes wobbly.

A lashing can also fail over time. Freshly cut wood shrinks as it dries, and the wraps loosen. Natural-fibre cord can get wet and stretch, or shrink later; cord can chafe on edges. So check lashings regularly and tighten them again. Load capacity depends on wood, cord and workmanship and cannot be stated in general terms.

The square lashing is the basic lashing for anything at right angles: frames, racks, tables, shelves and tarp frameworks. If you master it, you can build a great deal at camp with simple poles.

If the poles do not touch or spring away from each other, the diagonal lashing is the better choice. For anything that carries people or hangs over people: not without expert assessment. Life-safety use only after proper training with certified equipment.

Test every frame carefully and in stages before trusting it with anything valuable or heavy. Do not stand under loads hanging from it, and do not let anyone climb on untested structures – not even children, however tempting a home-built tower may be.

For the poles: check local rules before you cut wood. Dead, fallen wood can be rotten and break suddenly; tap it and test-bend it. Sisal, hemp or synthetic cord are suitable – what matters is that it pulls tight easily and is not too thick.