Cob House Building: Complete Beginner's Guide
Step-by-step, practical guide to planning and building a cob house for DIY eco-home builders. Materials, mixes, costs, moisture control, and next steps.
Cob House Building: Complete Beginner's Guide A cob house is a hand-built earthen structure formed from clay, sand and straw that can produce sculptural, low-cost walls with strong thermal mass. This guide explains what a cob house is, how to test soils and mix cob, a practical step-by-step build sequence from foundations to roof, moisture and insulation strategies for energy-efficient homes, realistic costs and timelines, and how cob compares with other natural building methods. Readers will learn specific cob mix recipes, foundation options, common failure modes to avoid, and next steps for a DIY cob build. TL;DR: - Cob walls: 350–600 mm (14–24 in) thick, low-material cost but high labor; expect 60–80% of onsite material needs from local soil. - Test and adjust: Use a jar-sediment and ribbon test, then make trial cob patches; common structural mix is roughly 1 part clay : 2–3 parts coarse sand with straw. - Protect from moisture: deep eaves (600–900 mm), raised foundations (rubble tr...