Proof challenge

Calculate Your Roof Runoff

Estimate your roof's footprint area and work out how much water one inch (or 25 mm) of rain sheds from it. Post your working.

How it works

1. Join the challenge.
2. Do the work, then post a public https link or a short write-up as proof.
3. An entry completes when it's approved or reaches 5 votes from other players. You earn +250 XP and the Finisher badge.

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Entries