Thermowood Redwood Cladding

Thermowood Redwood Cladding

This product is a special order item. Please speak to us concerning your needs.

Overview

Thermowood Redwood is a high-performance external cladding timber manufactured from sustainably sourced Scandinavian Redwood that has been thermally modified using only heat and steam. This specialist process significantly improves the timber's durability, dimensional stability and resistance to moisture without the use of chemical preservatives.

Retaining the natural character of softwood whilst offering enhanced performance, Thermowood Redwood is an excellent choice for both contemporary and traditional buildings. Its attractive grain, warm brown colour and improved stability make it one of the most popular timber cladding options available.

Appearance

Thermowood Redwood has a rich golden brown to chocolate brown colour when new, depending on the intensity of the thermal modification.

Unlike Ayous, Redwood displays a more pronounced grain pattern together with natural knots and character, giving each board a unique appearance. This makes it particularly suitable for projects where a more traditional or rustic timber aesthetic is desired.

What to Expect if Left Untreated

Thermowood Redwood does not require preservative treatment for durability.

If left untreated, UV exposure will gradually change the timber's colour from its warm brown tones to an attractive silver-grey patina. This weathering process is entirely natural and only affects the appearance of the timber, not its structural performance.

The speed and uniformity of the greying process will vary depending on the building's orientation, local climate and exposure to sunlight.

Recommended Treatments

Treatment is optional and depends on the desired appearance.

To retain the original brown colour

We recommend using a high-quality UV-protective exterior timber coating such as:

• Osmo UV Protection Oil
• Sansin SDF
• Teknos Exterior Wood Coatings
• Remmers Exterior Wood Finishes

These coatings help preserve the timber's natural colour, reduce UV degradation and minimise uneven weathering.

To achieve a natural silver-grey finish

No treatment is necessary.

Alternatively, pre-weathering coatings can be used where a consistent silver appearance is required immediately.

Durability

The thermal modification process substantially improves the natural durability of Scandinavian Redwood.

Durability Class: Class 2 – Durable

Suitable for long-term external cladding applications, Thermowood Redwood offers excellent resistance to fungal decay and moisture-related movement when correctly installed and ventilated.

With good design, installation and routine maintenance, an above-ground service life of 30 years or more can be expected.

Density & Weight

Approximate Density:

370–420kg/m³

Thermowood Redwood remains relatively lightweight despite the thermal modification process.

Benefits include:

• Easier handling on site.
• Faster installation.
• Reduced structural loading.
• Suitable for both domestic and commercial cladding projects.

Stability

One of the biggest advantages of Thermowood Redwood over untreated softwood is its significantly improved dimensional stability.

Thermal modification greatly reduces moisture absorption, resulting in:

• Reduced expansion and contraction.
• Lower risk of twisting.
• Reduced cupping.
• Improved long-term stability.
• Excellent suitability for rainscreen cladding systems.

Recommended Fixings

For external installations, corrosion-resistant fixings should always be used.

Recommended

? A2 Stainless Steel fixings for most inland applications.

? A4 Stainless Steel fixings for coastal and marine environments.

? Stainless steel cladding screws or ring shank nails.

Pre-drilling is recommended, particularly near board ends, to achieve the best finish and minimise the risk of splitting.

Typical Applications

Thermowood Redwood is ideal for:

• Residential cladding
• Garden rooms
• Garden offices
• Extensions
• Commercial developments
• Agricultural buildings
• Holiday lodges
• Soffits
• Fascias
• Contemporary and traditional façades

Advantages

• Thermally modified without chemical preservatives.
• Excellent dimensional stability.
• Naturally durable.
• Lightweight and easy to install.
• Attractive natural grain and character.
• Warm contemporary appearance.
• Can be left untreated to weather naturally.
• Easy to machine and work with.
• Excellent value for money.

Things to Consider

As with all natural timber products, Thermowood Redwood will gradually weather to a silver-grey colour if left untreated. This natural ageing process is often desired within modern architectural designs but can be slowed by applying a UV-resistant coating.

Due to the thermal modification process, the timber becomes slightly more brittle than untreated Redwood. Care should therefore be taken during machining and installation, with pre-drilling recommended when fixing close to board ends.

Good to Know

Thermowood Redwood is an excellent alternative to untreated Siberian Larch and standard pressure-treated softwood where improved stability and durability are required.

Compared with untreated Scandinavian Redwood, Thermowood Redwood offers:

• Significantly greater dimensional stability.
• Improved durability.
• Lower moisture movement.
• Reduced maintenance requirements.
• A rich, premium appearance without the need for preservative treatment.

It provides many of the performance benefits associated with premium timber cladding while remaining a cost-effective option for a wide range of projects.

Lanlee Performance Guide

Frequently Asked Questions

Does Thermowood Redwood need treating?

No. The thermal modification process provides the timber with enhanced durability without the need for preservative treatment. Coatings are only recommended if you wish to maintain the original brown colour.

Will Thermowood Redwood turn grey?

Yes. Like all natural timber exposed to UV light, it will gradually weather to an attractive silver-grey finish if left untreated.

Is Thermowood Redwood suitable for coastal areas?

Yes. When installed using A4 stainless steel fixings, Thermowood Redwood performs well in coastal and exposed environments.

Is Thermowood Redwood environmentally friendly?

Yes. Thermal modification uses only heat and steam, eliminating the need for chemical preservatives. Combined with responsibly sourced Scandinavian timber, it provides a sustainable solution for external cladding.

Lanlee Recommendation

Thermowood Redwood is an excellent all-round choice for customers looking for a durable, stable and attractive timber cladding at a competitive price. Its combination of natural character, improved performance and ease of installation makes it suitable for everything from contemporary garden rooms and extensions to large-scale commercial developments.

Compared to Thermowood Ayous, Redwood offers a more traditional appearance with visible grain and knots, making it ideal for customers who prefer a natural timber aesthetic while still benefiting from the enhanced durability and stability provided by the thermal modification process.