Every scene turns one piece of concrete arithmetic into something you can turn in your hand, with the master's secret and the mistake that costs money.
Illustration only: figures change with your mix, soil, local code and inspector. Strength, cover and joint rules come from ACI, PCA, ASTM and the California Building Code as tagged in each lesson. Structural work needs an engineer and a permit. Built 27 Oct 2026 for the Keep It In-House series.