LumberTherm Kuro Cladding Systems by Lumberbank

LumberTherm Kuro Cladding Systems

Lumberbank

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Description

The LumberTherm Kuro Cladding Systems comprise vertically and horizontally fixed exterior timber weatherboards manufactured from thermally modified Merbau (Heimu) hardwood. The chemical-free thermal modification process uses only heat and steam to alter the timber at a molecular level, while significantly improving its dimensional stability and natural decay resistance. The name Kuro translates to black in Japanese reflecting its rich pigment and deep, luxurious hue, Kuro naturally weathers to a silvered patina over time if allowed to do so.

The system is available in four primary profile groups:

Bevelback profile weatherboard (for horizontal fixing)
Rusticated profile weatherboard (for horizontal fixing)
Shiplap profile Weatherboard (for vertical fixing)
Board and Batten (for vertical fixing)

The weatherboards are installed over H3.2 treated timber castellated cavity battens (20mm non-structural or 45mm/70mm structural) to form a drained and ventilated wall cladding system designed to manage moisture.

Boards come in nominal thicknesses of 20mm, widths up to 230mm, and length spreads between 1.5m and 3.6m in Clear grade, along with complementary solid timber exterior mouldings and fascia boards. Available in two surface finishes; Smooth, for a refined aesthetic and a clean look; and Bandsawn, for natural, rustic character.

Key Features

CodeMark Certified: Certified pathway proving compliance with the New Zealand Building Code.
100% Chemical-Free Thermal Modification: Treated purely with heat and steam to enhance durability, decay resistance, and thermal insulation without toxic additives, plastics, or resins.
Enhanced Dimensional Stability: Thermal modification locks the wood cell walls, significantly restricting water absorption and movement compared to unmodified wood.
Hardwood: Kuro is Merbau hardwood providing a durable and hardwearing exterior envelope.
Diverse Architectural Profiles: Offered in Vertical Shiplap, Bevelback, Horizontal Rusticated, and Vertical Board & Batten profiles.
Surface Finishes: Available in Smooth — for a refined aesthetic and a clean look; and Bandsawn — for a natural, rustic character.
Integrated Cavity System: Utilises MicroPro H3.2 treated Radiata Pine castellated cavity battens to maintain effective drainage and ventilation.

Scope of Use

LumberTherm Kuro Cladding Systems are suitable for use as an external wall cladding on residential, civic, and commercial timber-framed buildings under the following conditions:

Building Height: Up to 10m in height.
Wind Zones: Suitable for wind zones up to and including Extra High (as defined in NZS 3604) or a maximum design differential ULS wind pressure of 2.5 kPa (in accordance with B1/VM1).
E2 Risk Score: Suitable for buildings with an E2/AS1 risk score of 0–20 when installed over a cavity. (Note: Direct-fixed applications are permitted only where the risk score is ≤12 for Bevelback/Board & Batten, or ≤6 for Rusticated/Vertical Shiplap).
Exposure Zones: Suitable for all exposure zones as defined in NZS 3604 (excluding microclimates).
Boundary Location: Suitable for installation on walls located more than 1m from a relevant boundary.
Framing Substrates: Fixed over flexible building underlays or rigid air barriers supported by timber framing complying with NZS 3604 or NZS 3603.
Joinery Integration: Compatible with aluminium-framed window and door joinery complying with NZS 4211.

See CodeMark for full information.

Limitations on Use

Must be designed and installed in accordance with LumberTherm's technical documentation.
Not certified for installation within 1m of a relevant boundary.
Must be fixed using 316 Stainless Steel annular grooved nails; fixings must achieve a minimum 30mm embedment into framing or structural cavity battens.
Direct fixing is restricted to E2 risk scores ≤12 (Bevelback and Board & Batten) or ≤6 (Rusticated and Vertical Shiplap) in accordance with E2/AS1.
Coating is required to maintain long-term aesthetic appeal — follow Coating and Maintenance Guide for information.

Statement of Building Code Compliance

LumberTherm Kuro Cladding Systems, if designed, installed, and maintained in accordance with the manufacturer's technical literature and CodeMark CMNZ70165, comply with or contribute to compliance with the following performance provisions of the NZ Building Code:

Clause B2 DURABILITY: Performance B2.3.1 (b) [15 years] and B2.3.2 (b)
Clause E2 EXTERNAL MOISTURE: Performance E2.3.2 (contributes to), E2.3.5 (contributes to), E2.3.6 (contributes to), and E2.3.7
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1

Other Performance Attributes

Sustainably harvested hardwood processed without toxic chemicals, heavy metals, or resins.
Thermal modification improves the wood's natural thermal insulation properties over standard softwoods/hardwoods.

Coating & Maintenance

A suitable coating is recommended to ensure the long-term visual appeal LumberTherm Kuro cladding, it is recommended to apply a suitable coating.
Leaving the cladding uncoated or using clear coatings will not achieve the desired level of aesthetics over time, although it will still meet durability and weather tightness standards as per E2/AS1.
Dark colours (coatings with an LRV of below 45%) will exceed the 15-year durability, however will require an increased level of re-coat and general product maintenance compared to where light coating colours are used.

See Guiding & Maintenance Guide for full information.