Structure II — Natural Materials & Alternative Systems
Test a site's soil for building suitability, choose between the earthen and fibrous systems for a given climate and application, build and finish walls in each, and specify clay, lime and gypsum plaster systems that let a wall dry.
What you'll be able to do
- Test and judge a soil for building use
- Choose deliberately between five wall systems for a given climate
- Specify a plaster system that matches the wall behind it
- Lay an earthen floor and detail a wall base that stays dry
Syllabus
6 parts · 19 lessons · 120 quiz questions · ≈5.1 hours of reading · sign in to open lessons
Part A MATERIAL INTELLIGENCE
- 1 The Natural Building Proposition 18 min · 7 q
- 2 Thermal Mass vs Insulation — the Core Tension 15 min · 6 q
- 3 Soil — Testing What You Have 15 min · 6 q
Part B EARTHEN WALL SYSTEMS
- 4 Adobe 19 min · 7 q
- 5 Cob 16 min · 6 q
- 6 Rammed Earth 17 min · 7 q
- 7 Choosing Between the Three 14 min · 6 q
Part C INSULATIVE WALL SYSTEMS
- 8 Straw Bale — Types, Sourcing and Assembly 17 min · 6 q
- 9 Straw Bale — Moisture Management and Plaster 15 min · 6 q
- 10 Hempcrete 15 min · 6 q
Part D PLASTER SYSTEMS
- 11 Plaster as a System 14 min · 6 q
- 12 Clay Plaster 17 min · 7 q
- 13 Lime Plaster and Limewash 17 min · 7 q
- 14 Gypsum, Colour and Texture 14 min · 6 q
Part E EARTHEN FLOORS
- 15 Earthen Floors — Assembly 17 min · 7 q
- 16 Earthen Floors — Finishing and Maintenance 13 min · 6 q
Part F STRUCTURE, ROOFS AND PERMITTING
- 17 Matching Structure to Material 13 min · 6 q
- 18 Living Roofs and Roof Selection 14 min · 6 q
- 19 Getting Non-Standard Materials Permitted 14 min · 6 q
Ref Appendices
- A1 Material Selection Matrix
- A2 Mix Reference
- A3 New Mexico Code Quick Reference — 14.7.4 NMAC
- A4 The Moisture Rules
Prerequisites
Recommended: Course 3 (Structure I — Biotecture & Tire Wall Construction)
About this course
Course competency
On completing this course you can test a site's soil for building suitability, choose between adobe, cob, rammed earth, straw bale and hempcrete for a given climate and application, build and finish walls in each, specify and apply clay, lime and gypsum plaster systems, lay an earthen floor, match a roof and structural system to the wall material you have chosen, and take a non-standard material through a building department.
Why this course exists
Course 3 taught one wall system in depth. This course teaches you to choose.
A tire wall is extraordinary at what it does and wrong for several things. It is massive and barely insulating, which makes it superb in a bermed, glazed, high-diurnal-swing climate and a poor choice above grade in a cold cloudy one. It needs a backhoe and a large crew. It cannot be built at the top of a mountain with no vehicle access.
Every material in this course exists because somewhere, for someone, it was the right answer when earth-in-tires was not.
The skill this course builds is material literacy — knowing enough about seven or eight systems to put the right one in the right place, and knowing the specific ways each of them fails.
The one idea that organises everything here
Natural materials are not interchangeable, and the thing that differentiates them most is how they handle water.
Every system in this course is structurally adequate when built correctly. Almost none of them fail structurally. They fail by getting wet and not being able to dry. Adobe erodes at the base under an inadequate overhang. Straw bale rots behind acrylic stucco. Cob softens where it meets a foundation with no capillary break. Hempcrete and clay plaster both fail under latex paint.
So the through-line of this course is a single rule, stated in Course 3 and repeated here because it governs everything:
Every wall assembly must be able to dry in at least one direction.
A capillary break at an interface is not a vapour barrier across an assembly. The first is nearly always right. The second is nearly always wrong.
Course structure
| Part | Lessons | Subject |
|---|---|---|
| A | 1–3 | Material intelligence: embodied energy, the mass/insulation tension, and soil |
| B | 4–7 | Earthen walls: adobe, cob, rammed earth, and choosing between them |
| C | 8–10 | Insulative walls: straw bale and hempcrete |
| D | 11–14 | Plaster systems: clay, lime, gypsum, colour and texture |
| E | 15–16 | Earthen floors |
| F | 17–19 | Structure, roofs, and getting it permitted |
| — | A1–A4 | Appendices: selection matrix, mix reference, glossary, moisture rules |
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