PDC Natural Building & Shelter Design 2

Question 1

Adobe construction is distinguished from cob primarily by which characteristic?

Accepted Answer

Using pre-formed, sun-dried earthen bricks laid in courses

Answer

Using synthetic polymer binders instead of clay

Answer

Being poured in place like conventional concrete

Answer

Requiring kiln firing for adequate structural strength

Question 2

What is the primary structural advantage of rammed earth construction over other earthen building techniques?

Accepted Answer

It creates dense, load-bearing walls with high compressive strength

Answer

It has very high insulation values comparable to rigid foam board

Answer

It requires no formwork or specialized equipment to construct

Answer

It is the lightest of all natural building materials per square foot

Question 3

How do Compressed Earth Blocks (CEB) primarily differ from traditional sun-dried adobe bricks?

Accepted Answer

They are mechanically pressed to achieve higher density and uniformity

Answer

They use fired clay rather than sun-dried materials

Answer

They incorporate Portland cement as a stabilizer in all formulations

Answer

They are only suitable for below-grade foundation construction

Question 4

A thermal chimney (solar chimney) in a natural building functions by using which physical principle?

Accepted Answer

Using heated air's natural tendency to rise, drawing cooler replacement air in at lower openings

Answer

Burning biomass fuel to heat air and distribute it through the building via ducts

Answer

Using solar panels to power a fan that circulates cool air from underground

Answer

Reflecting sunlight off mirrored surfaces onto water to generate cooling steam

Question 5

In natural building, a 'rain screen' wall assembly primarily protects against what problem?

Accepted Answer

Water infiltration by creating a drainage and drying cavity behind the outer cladding

Answer

Ultraviolet radiation degrading natural clay plasters over time

Answer

Wind loads exceeding the structural capacity of earthen wall systems

Answer

Insect infiltration through hairline cracks in natural plaster finishes

Question 6

Cordwood (stackwall or log-end) construction primarily uses which building technique?

Accepted Answer

Short, debarked log sections stacked perpendicular to the wall face within a mortar matrix

Answer

Whole timber logs notched and stacked horizontally in a log cabin style

Answer

Split firewood bundled and tied with wire to serve as insulation panels

Answer

Milled dimensional lumber alternated with earthen mortar in horizontal courses

Question 7

What is the primary moisture-related challenge builders must address in straw bale construction?

Accepted Answer

Straw bales must be kept dry before and during construction to prevent mold and rot

Answer

Straw shrinks excessively when dry, leaving structural gaps throughout the wall

Answer

Finished straw bale walls cannot accept any type of plaster or render coating

Answer

Straw loses all insulative value when exposed to cold winter temperatures