Takekomai (竹小舞) is the intricate split-bamboo structural lattice that serves as the flexible internal reinforcement core for Tsuchikabe earthen walls. Crafted from seasoned Japanese timber bamboo (Madake), the vertical uprights (tate-komai) are sprung into pre-drilled holes in timber posts, while horizontal slats (yoko-komai) are interwoven and tied at every crossing node using continuous black palm fiber twine (shuronawa). This nail-free lattice flexes with seismic ground waves while locking clay mud in place.
At a Glance: Key Takeaways
- Bamboo Species: Japanese Timber Bamboo (Madake, Phyllostachys bambusoides)
- Grid Spacing: 25mm to 35mm square lattice openings
- Slit Dimensions: 10mm to 15mm width × 4mm to 6mm thickness
- Twine Material: Natural Shuronawa (Twisted hemp-palm Trachycarpus fiber)
Madake Bamboo Harvesting, Curing, and Longitudinal Splitting
Not all bamboo is suitable for architectural lathing. Master sakan artisans insist on Madake (Phyllostachys bambusoides) harvested strictly in mid-winter (November to January) when starch levels in the culm are lowest, preventing powder-post beetle infestations.
Mature 3-to-4-year-old culms are split longitudinally using multi-bladed cast-iron bamboo splitters (take-wari). The inner pith is scraped away, leaving flexible, resilient strips (12mm wide by 5mm thick) that retain the dense, silica-rich outer green rind (take-kawa) for maximum tensile resistance.
Shuronawa: The Superiority of Hemp-Palm Fiber Twine
Binding the bamboo lattice requires a cord that will never rot inside wet, alkaline clay mud. The universal Japanese choice is Shuronawa—a two-ply cord hand-twisted from the coarse, dark brown sheath fibers of the windmill palm (Trachycarpus fortunei).
Shuro fibers are naturally impregnated with natural waxes and tannins, making them completely waterproof and biologically rot-resistant in damp subterranean conditions for centuries. Furthermore, Shuronawa has high surface friction, gripping the smooth bamboo stalks tightly without slipping even during severe seismic shaking.
Knotting Choreography: The Continuous Figure-Eight Lashing
Tying a Takekomai grid is an athletic, continuous rhythm. Sakan artisans do not cut individual pieces of twine for every node. Instead, a continuous ball of Shuronawa (often 50 meters long) is worked in diagonal sweeps across the wall.
At each intersection where a horizontal slat crosses a vertical bamboo, the craftsman executes a swift figure-eight loop, tensioning the cord with a wrist snap before advancing to the next node. Because the twine is continuous, tensile stress is distributed dynamically across the entire wall plane rather than concentrating at isolated points.
Anchorage Systems: Pre-Drilled Sockets and Side Grooves
The Takekomai lattice must anchor into the main structural timber frame (cedar or cypress posts) without rigid metal brackets. Carpenters chisel continuous 15mm triangular grooves (nawa-mizo) or drill sequential 12mm holes along the centerlines of the wooden columns.
The vertical bamboo laths (tate-komai) are cut slightly long, bent into an arc, and sprung into the opposing top and bottom sockets. Peripheral bamboo border canes are lashed directly into the wooden post grooves with Shuro twine, ensuring that the finished earthen wall behaves as a unified, monolithic diaphragm with the building's timber frame.
Takekomai Grid Dimension & Material Specifications
Use this reference table to calculate exact physical dimensions, ratios, and specifications before purchasing:
| Lattice Component | Bamboo Material | Nominal Dimensions | Grid Spacing Center | Fastener / Tie Method |
|---|---|---|---|---|
| Vertical Uprights (Tate-Komai) | Split Madake heart-bamboo | 12mm – 15mm width × 5mm thick | 30mm to 35mm centers | Sprung into cedar beam sockets |
| Horizontal Slats (Yoko-Komai) | Outer-rind Madake strips | 10mm – 12mm width × 4mm thick | 25mm to 30mm centers | Woven alternately over uprights |
| Border Support Cane (Mawashi) | Whole round bamboo cane (25mm) | Full length of wall perimeter | Anchored in post lateral groove | Heavy double-wire tie to posts |
| Lashing Twine (Shuronawa) | Pure Trachycarpus palm fiber | 2.5mm two-ply twisted cord | Every bamboo intersection | Continuous figure-eight tension knot |
Practical Constraints
Every successful decoration project must account for physical and environmental constraints:
Physical Blistering and Abrasion from Rough Shuro Twine
Tying thousands of high-tension palm twine knots requires artisans to tape fingertips or wear specialized split-leather knotting gloves.
Time-Consuming Hand Knotting of Large Wall Areas
A standard 8-mat room requires over 4,000 individual hand knots, demanding 2 full working days per room for lathing alone.
Execution Blueprint & Craftsmanship Sequence
Execute this professional sequence to achieve flawless results without backtracking:
Madake Bamboo Splitting and Dressing
Split 3-year-old winter-cut Madake culms into 12mm wide slats using a multi-blade splitter; scrape away internal soft pith.
Timber Post Socket Drilling
Drill 12mm blind holes at 35mm centers into horizontal nageshi beams and sill plates along the wall centerline.
Tate-Komai Vertical Upright Springing
Cut vertical bamboo laths 20mm longer than opening; bow slats into an arc and spring into top and bottom sockets, straightening into alignment.
Yoko-Komai Horizontal Interweaving
Weave horizontal bamboo slats across the uprights, alternating front and back positions across successive columns to create spring tension.
Continuous Shuronawa Figure-Eight Knotting
Lash every intersection node with continuous black Shuro palm twine using a figure-eight tension knot, pulling each node tight with a wrist snap.
Lattice Rigidity Inspection
Press the completed bamboo mesh firmly with both hands; verify zero loose nodes and ensure consistent 30mm apertures for mud keying.
Common Mistakes & Countermeasures
Avoid these costly errors that compromise aesthetics, ergonomics, and budget:
Using Bamboo Harvested During Spring or Summer Months
Tying Grid Openings Too Tightly (<15mm Gaps)
Project Execution Checklist
Track your physical progress. Checkboxes persist automatically on this device:
Frequently Asked Questions
Why is the green outer rind of bamboo preserved in Takekomai?
The outer rind contains high concentrations of natural amorphous silica and lignin, providing immense tensile strength and natural resistance against moisture rot and insect penetration.
Can galvanized wire replace Shuro palm twine for tying bamboo?
Historic restoration strictly rejects metal wire. Steel wire creates rigid, sharp pressure points that cut into bamboo fibers under building vibration, whereas natural palm twine flexes elastically without damaging the wood.
