Earth-Sheltered • Efficient Spans • Resilient
Concrete Arches
Concrete arches let us carry heavy soil loads in compression, enabling generous spans with slim structure and low maintenance for earth-sheltered homes.
Why Concrete Arches for Earth-Sheltered Houses
An arch carries load primarily in **compression**; horizontal **thrust** at the springings is resisted by abutments or tie systems. This makes arches ideal where roof soil adds significant permanent load—fewer tensile demands, fewer joints, and excellent durability.¹²
Performance
- Handles heavy soil & live loads efficiently (compression-dominant)
- Reduces vulnerable edges, eaves and junctions
- Slim structure enables lower profile in the landscape
Economy
- Less external cladding & finishes
- Simple repeatable forms; efficient shuttering
- Adaptable to mezzanines, courtyards & cluster layouts
Typical Spans & Dimensions
Our concrete arch roofs are often about 120 mm thick—versus ~380 mm for equivalent flat systems at similar spans—because the arch works in compression. Common planning modules include widths around 7,200 mm and crown heights near 4,350 mm, adaptable to different programs.
Plans & Concepts
Waterproofing & Green Roof Build-Up
Earth cover requires a robust roof build-up: **waterproofing membrane + root barrier → protection board → drainage layer → filter fabric → growing medium/soil**. Correct falls and edge detailing move water to drains without ponding; the drainage layer protects the membrane and reduces hydrostatic pressure.³⁴⁵
Bushfire Detailing (BAL)
For bushfire-prone sites, construction follows **AS 3959** requirements by BAL level. Typical measures include ember-proof screening (≤2 mm aperture) to vents and weepholes, non-combustible claddings and compliant shutters at higher BALs (BAL-40/BAL-FZ).⁶⁷⁸
Our arch forms naturally reduce eaves and roof cavities—common ember entry points—and allow protected **airlock entries** and **sealed junctions** that integrate with the earth berms.
Thermal Performance & Comfort
Earth-sheltered envelopes leverage the **thermal inertia of soil** to buffer outdoor extremes, stabilising indoor temperatures and reducing peak loads. With correct insulation/waterproofing, these homes can achieve excellent year-round comfort and low operational energy.⁹¹⁰¹¹
Typical Construction Sequence
- Excavate benches/footings; place subsoil drains to daylight/sumps.
- Form and pour arch shells (or place precast); integrate thrust blocks/abutments or ties.
- Apply roof **waterproofing** and **root barrier**; add protection board.
- Install **drainage mat**, **filter fabric**, and growing media; set overflows.
- Backfill berms in compacted lifts; finalize surface drainage & erosion control.
- Fit openings with compliant **screens/shutters** per BAL; commission ventilation.
Maintenance & Cost Drivers
Maintenance
- Annual inspection of drains, overflows and membrane terminations
- Vegetation management on berms (roots, irrigation, erosion)
- Check ember screens/shutters and seals prior to bushfire season
Cost Levers
- Module efficiency (repeat arch bays, standard radii)
- Soil availability/haul distances for berms
- Waterproofing system selection & access complexity
- Extent of glazing/roller shutters for BAL compliance
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