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BioDome

Living Roof

The living roof is what makes the BioDome truly fire-resistant and thermally regulated. A layer of growing plants and soil on top of the roof structure absorbs heat, holds moisture, and blends the structure into the landscape.

  1. Sheathing

    Cork board or dense wood fiber board over purlins.

  2. Waterproofing

    EPDM pond liner (1mm minimum) fully lapped and sealed.

  3. Root Barrier

    Drainage mat + filter fabric to prevent roots from penetrating the waterproof membrane.

  4. Growing Medium

    10-15cm lightweight substrate (pumice/perlite/compost mix).

  5. Planting

    Sedums, native succulents, drought-tolerant groundcovers.

BioDome with mature living roof blending into hillside landscape
The living roof matures over time, blending the structure into the landscape
Cross-section of living roof layers: sheathing, EPDM, drainage mat, filter fabric, growing medium, plants
Living roof layer sequence: from structural sheathing to growing plants
Reciprocal roof frame structure with interlocking rafters
Reciprocal roof: interlocking rafters that support each other without a central post
Reciprocal roof spiral pattern viewed from below
The reciprocal spiral — each rafter rests on the next, creating a self-supporting ring

Central Opening Waterproofing

Section titled “Central Opening Waterproofing”

The ~1m diameter central opening is the lowest point of the dome apex. Without proper detailing, water from the living roof drains toward this opening.

  • Raised curb: Install a 150mm high curb around the opening using cork or treated timber. EPDM membrane wraps up and over this curb.
  • Metal flashing collar: A pre-formed aluminum or stainless steel collar (1.2m outer diameter) sits atop the curb with a 45° drip lip directing water outward.
  • Drainage relief: Cut 4 small notches (25mm wide × 10mm deep) in the curb at cardinal points to allow trapped water to escape to the main roof drainage layer.
  • Skylight or cap: The opening should be sealed with a glazed dome, operable hatch, or removable weatherproof cap. Do not leave open to weather.

Roof Overflow Protection

Section titled “Roof Overflow Protection”

Living roofs can retain significant water during intense winter storms. If the drainage mat capacity is exceeded, water must have an escape path.

  • Overflow scuppers: Install 2-4 overflow outlets (75mm diameter PVC pipe through EPDM, sealed with rubber boot) at the low points of the roof perimeter.
  • Outlet height: Set scupper inlet 50mm above normal drainage layer level — water only exits when drainage is overwhelmed.
  • Discharge: Direct overflow away from foundation via splash blocks or gravel drainage strip.