Concrete arches
Concrete arches for
earth-sheltered homes
Arches carry soil and roof loads predominantly in compression, enabling slim shells, generous spans and resilient low-profile forms. Below we outline ten strategies we use to make arch-based homes comfortable, durable and buildable.
Typical shell thickness (design-dependent)
Column-free rooms under planted roofs
Reduced wind/storm exposure
Mass + planting buffer noise
Why arches work for earth-sheltering
An arch carries loads primarily in compression. For earth-sheltered roofs, this is ideal: the overburden of soil and water acts downward, and the arch thrusts are resolved by foundations and returns at each side. Compared with flat systems, arches can achieve slender build-ups, longer spans and fewer internal supports.
When combined with correct detailing—continuous insulation, layered waterproofing, robust drainage and careful daylighting—the result is a quiet, durable envelope with stable internal temperatures and low energy use.
Every site is different. Soil profile, groundwater, exposure, BAL context and the desired program all influence the final geometry and details.
Typical components at a glance
- Reinforced concrete arch shell with consistent radius or tangent segments
- External waterproofing layers with protection board and drainage mats
- Gravel backfill and perimeter drains relieving hydrostatic pressure
- Continuous insulation to control heat flow and avoid condensation
- Recessed openings with shading and ember-resistant screens where relevant
- Planted roof build-up (soil depth and species per climate/ecology)
Approach
10 smart concrete-arch strategies we use
Strength with less material
Shells as slender as ~120 mm (design-dependent) can outperform flat roofs of 300–380 mm for similar spans—saving material and head height.
Long, column-free rooms
Arches carry vertical loads and soil surcharge efficiently, unlocking generous spaces and flexible planning under planted roofs.
Keep water out—let vapour dry
Drainage mats, positive falls, inspection details and redundant membranes relieve pressure and simplify maintenance.
Comfort without overheating
Clerestories between bays, recessed glazing and shaded courtyards pull light and air deep into plans while managing summer gain.
Stable, quiet interiors
Concrete and earth moderate temperature swings; combined with insulation continuity and airtightness they reduce peak loads.
Repeatable bay modules
Formwork and reinforcement are rationalised into repeatable bays; services run between arches for simple coordination.
Wind, storm & ember resistance
Low-profile forms with protected openings perform well in severe weather and bushfire contexts when detailed correctly.
Robust edges & penetrations
At eaves, parapets and service penetrations we add protection boards and compression seals to safeguard membranes.
Easy inspection & maintenance
Dedicated inspection points and accessible drainage runs support long-term performance with minimal disruption.
Planted roofs that give back
Planting restores ecology, cools the microclimate and buffers sound. Soil depth and species are tuned to rainfall and exposure.
Arches vs flat roofs—at a glance
| Aspect | Concrete arches | Flat roof build-up |
|---|---|---|
| Span & structure | Efficient in compression, long spans | Beams/slabs; heavier for same span |
| Roof thickness | Slim shells (design-dependent) | Typically thicker to control deflection |
| Waterproofing | Continuous over simple geometry | Multiple planes & more junctions |
| Wind/storm exposure | Reduced profile | Higher profile; more exposed |
| Complexity | Specialist design/formwork | Widely standardised |
How we deliver arch-based projects
- Site & goals. Orientation, slope, access, vegetation, view corridors and BAL context.
- Options & feasibility. Radius and bay studies, soil/rock considerations, daylight and drainage paths.
- Design development. Structure, membranes, insulation, openings, services and planted roof build-ups.
- Approvals & documentation. Drawings, specs and coordination with consultants.
- Tender & construction support. Clarifications, shop-drawing review and quality checkpoints.
Good to know
- Arch geometry may be a constant radius, parabolic, or segmented to suit spans, head heights and views.
- We design for inspection access to membranes and drains, with redundant paths at critical points.
- Openings are recessed for shade and protection; bushfire screens and non-combustible claddings are specified where applicable.
- Mechanical ventilation can be balanced with heat recovery in tight envelopes or smoky environments.
Want the detailed step-by-step? See our 6-step process.
Frequently asked questions
Will a concrete arch cost more than a flat roof?
It depends on span, access and formwork method. Material savings from slimmer build-ups can offset formwork cost, particularly where long spans or planted roofs are desired.
How do you waterproof an earth-covered arch?
We use layered membranes over a smoothed substrate, protection boards, drainage mats and positive falls to perimeter drains. Critical edges and penetrations receive reinforced terminations and compression seals.
Can arches meet bushfire requirements?
Yes—siting, recessed openings, non-combustible finishes and ember-resistant screens are combined with BAL-appropriate detailing. See our bushfire-responsive design.
What about interior planning under arches?
Bays provide a natural rhythm for rooms; clerestories between bays bring daylight and assist ventilation. Services can run in inter-bay zones for simple coordination.
Considering concrete arches?
Book an initial chat and we’ll map options for your site, structure and budget.