Finishing Techniques

Lime Render

• Base coat: 1:3 lime:sand, 15mm thick
• Finish coat: 1:2.5 lime:fine sand, 5mm thick
• Limewash: 3-4 coats for final protection

Why Lime, Not Cement

Lime render is breathable — it allows moisture to pass through the wall rather than trapping it. Cement render on straw-clay walls creates a vapor barrier that leads to rot. Lime also self-heals small cracks through carbonation.

Windows & Doors

Use Chestnut for Precision Joinery

While eucalyptus is ideal for structural framing (posts, wattle poles, rafters, purlins), its tendency to warp and twist as it dries makes it unsuitable for precision millwork. Window frames, door frames, and mullions require dimensional stability for tight weatherseals and smooth operation. For these applications, use chestnut (Castanea sativa) — a native Mediterranean hardwood with excellent stability, natural rot resistance from high tannin content, and a long tradition of use in Portuguese building.

Deep reveals (40cm+) create natural window seats.

Sill Pan (All Windows)

• Slope: Window sills must slope outward at minimum 15° (1:4 ratio)
• Pan liner: Install EPDM or metal pan liner beneath window frame, extending 50mm up frame jambs and 100mm beyond sill edge
• Drip edge: Sill must project 40mm beyond wall face with undercut drip groove
• End dams: Turn up pan liner at both ends to prevent water running along sill into wall

Head Flashing (All Openings)

• Z-flashing: Install galvanized or aluminum Z-flashing above all window and door heads
• Extension: Flashing must extend 50mm beyond frame on each side
• Overlap: Lime render overlaps top leg of flashing; bottom leg overlaps frame head

Door Threshold

• Elevation: Door threshold must be minimum 50mm above exterior grade
• Drainage: Slope exterior surface away from threshold at 2% minimum
• Weather strip: Install adjustable door sweep or threshold seal

Avoid Roundwood Frames for Exterior Openings

Roundwood makes attractive interior trim but performs poorly at weathered exterior openings. The irregular surface creates gaps that are difficult to seal. Use kiln-dried, dimensioned timber (chestnut, oak, or treated softwood) for all window and door frames exposed to weather.

The finished result: lime render, stone base, and climbing plants integrate the dome into its setting

Clean exterior finish with stone surrounds and lime-rendered walls

Floor Options

1. Earthen floor: Clay/sand/linseed finish (beautiful, requires maintenance)
2. Flagstone on sand: Durable, attractive, low maintenance
3. Polished concrete: Practical, can integrate radiant heating