Cut a Drainage Trench Before You Need It
A shelter that's dry at dusk can be sitting in standing water by the middle of the night.
The uphill side and any low point around your shelter's footprint where runoff would naturally collect.
Even a well-sited shelter can pool water at its own footprint once a roof starts diverting rainfall onto the ground beside it.
Dig a shallow trench on the uphill side, angled to carry water around and away from the shelter, not just off the roof and onto the ground next to you.
Pour a small amount of water at the uphill edge and watch where it actually travels — redirect the trench if it doesn't clear the footprint.
Trenching only the direction you expect rain from. Wind-driven rain and roof runoff itself can approach from any side.
Shingle the Roof, Don't Just Pile It
Water runs off overlapping layers. It finds its way straight through a single flat pile.
Roofing material — bark, boughs, or debris — laid in overlapping rows from the bottom up, the way shingles are laid on a house.
A single thick layer laid flat still has gaps and seams that water finds. Overlapping rows shed water the way each layer sheds onto the one below it.
Start at the bottom edge of the roof and work upward, so each new row overlaps the row below it rather than butting against it.
Trickle water at the peak and watch whether it runs off the shingled surface or pools and seeps through a seam.
Building the roof from the top down, which leaves upslope-facing seams that catch and funnel water inside instead of shedding it.
Re-Run the Site Checks as Light Fades
Wind, drainage, and hazard signs you read earlier can change by the time you actually need the shelter.
The same wind, drainage, and overhead hazard signs from earlier in the path, checked again in the last light before dark.
Conditions — wind direction, a cracking limb, a cloud bank — can shift over hours. The read you did when you chose the site isn't guaranteed to still hold.
Walk the same hazard and wind scan from earlier steps once more before full dark, while you can still see and still fix a problem.
Compare the current wind direction against the leeward siting you chose earlier — if it's shifted significantly, adjust your entrance or wall orientation now.
Treating the site read as a one-time task completed hours earlier instead of a check worth repeating right before you commit for the night.
If the wind, drainage, or hazard signs have changed since you sited the shelter, adjust the shelter now, in the last light, not after dark.
Treating the site read from earlier in the day as permanent. Conditions shift, and the only safe window to fix it is before dark.
Trench it, shingle it, then re-check it before the light goes.