This step by step diy woodworking project is about 12×16 barn shed roof plans. the project features instructions for building a gambrel roof for a 12×16 barn. Lean-to shed is the simplest style, consisting of a single sloping roof is probably lowest in construction cost and easy to frame, ideal for the beginner who wants a. Lean to shed plans. free diy lean to shed blueprints for constructing your own wooden lean to shed. includes step-by-step building instructions and detailed color.