Larch

Species and Origin

• Siberian Larch (Larix sibirica), also known as Russian Larch, is a slow-growing softwood originating from Siberia. It is native to a very cold climate and can grow up to 50 metres when mature.

Appearance

• Siberian Larch has a natural yellow-golden brown color. Over time, it weathers to a silvery-grey color due to moisture and UV rays. This weathering process can be slowed down or controlled with the use of woodcare finishes.
• The wood has a distinctive grain and texture, making it aesthetically appealing for cladding.

Durability and Dimensional Stability

• Siberian Larch is highly durable and dimensionally stable due to its natural substances and cellular structure. It has excellent resistance to moisture and wood-decaying fungi, which helps avoid warping, cracking, and splitting.
• On the Janka hardness scale, Siberian Larch scores 1,100 lbf, making it denser and harder than Western Red Cedar (350 lbf), and even many hardwoods.

Maintenance and Treatment

• Untreated Option: Siberian Larch can be left untreated, allowing it to age naturally. However, applying a clear waterproofing oil can protect the wood from damage while maintaining its natural look.
• Clear and Semi-Transparent Oils: Products like Owatrol H4 Wood and Owatrol Seasonite provide good protection against water and fungal attacks without significantly altering the color. These finishes typically need a top-up every one-to-two years.
• Restoration: If the larch cladding has weathered or has older finishes, products like Owatrol Net-Trol and Owatrol Prepdeck can be used to restore the original color and prepare the surface for new treatments.
• Regular Inspection: Regularly inspect the cladding for any signs of damage or wear and address these issues promptly to maintain its condition.

Cost

• Siberian Larch cladding is generally cheaper than Western Red Cedar. For example, Grade A Siberian Larch can cost around £70 per m², while Western Red Cedar costs around £80 per m². B Grade Siberian Larch can offer an even more cost-effective solution.

Installation

• Ensure breathable sacking is installed against the frame and a minimum 20mm batten gap to create an air gap, which helps minimize wastage and prevent moisture issues.
• Install trims first, including internal and external corners, edge flashings, and starter bars. Ensure proper flashing above windows and doors to keep moisture out.
• Cladding boards should be installed starting from the bottom, working upwards. For horizontal installations, ensure the tongue faces upwards and fix the boards at a 45-degree angle to cover the fastener heads.
• Apply a full coat of penetrating oil to all four sides of the boards before and after installation to protect the wood and cover any marks or hand prints.

Additional Considerations

• Safety and Handling: If considering a charred finish like shou sugi ban, ensure all safety precautions are taken, including using heatproof gloves and working in a safe, well-ventilated area away from flammable materials.
• Design Flexibility: Siberian Larch can be used in various creative projects, including vertical and horizontal cladding, and can be combined with other materials like Douglas fir for structural elements.

By considering these aspects, you can ensure that your Siberian Larch cladding project is both aesthetically pleasing and durable, with proper maintenance and cost-effectiveness in mind.