A lean-to is an easy overnight shelter to build in a wooded area. All you need to carry are 25 feet of light line and an 8- x 10-foot plastic tarp or drop cloth, equipped with tie lines or grommets.
Look for two trees 3 to 4 feet apart to serve as upright supports. Then find three straight poles for the frame
work-two 7 or 8 feet long, and the other about 1 foot longer than the distance between the two trees. If you must cut saplings for these poles, choose young birches, poplars, or aspens that grow close to larger trees; they will soon be shaded out anyway.
Lash the short pole to the windward side of the two trees 2 feet from the ground if the shelter is just for sleeping; 3 or 4 feet if you plan to sit up and cook. Rest the ends of the long poles on this crossbar so that the lean-to’s open side will face leeward (downwind), and lash them in place. Stretch the tarp over this framework and lash it to the crossbar. Fashion pegs from sticks to hold down the edges; then pile dirt to seal out the wind.
In an emergency, you can make a lean-to that is almost as weatherproof by covering the framework with slender branches and evergreen boughs. Or find an evergreen tree with a low branch, and lean evergreen boughs against it. In winter, pack snow over the boughs for insulation.