Understanding Thermally Modified Wood for Wall Applications
Thermally modified wood undergoes a high-heat treatment process that alters its cellular structure. This process aims to reduce the wood's tendency to absorb moisture, which can contribute to greater dimensional stability compared to untreated wood. For covered patio walls, where exposure to direct weather is reduced but humidity fluctuations can still occur, this stability is a key advantage.
The thermal modification process also imparts a consistent, darker tone throughout the wood, typically a rich brown. This color can deepen or lighten over time depending on UV exposure and chosen finishes. While the wood's natural properties are enhanced, it remains a wood product and will interact with its environment.
When considering thermally modified wood for walls, it's important to differentiate between general-purpose lumber and profiles specifically designed for cladding or siding. Wall applications typically require profiles that allow for proper fastening and create a visually appealing surface, often with specific shadow lines or joint details.
Selecting the Right Profile and Species
For covered patio walls, several profiles of thermally modified wood are suitable. Tongue and groove (T&G) profiles are a common choice, offering a clean, interlocking appearance and simplifying installation. Shiplap profiles provide a distinctive overlap and a strong shadow line, which can add architectural interest.
The choice of species is also important. NORX thermally modified wood, for instance, is available in profiles such as 1x6 and 1x4 tongue and groove, which are well-suited for vertical or horizontal wall applications. These dimensions refer to the nominal size; the actual dimensions will be slightly smaller due to milling.
When planning, consider the desired aesthetic: a wider board like a 1x6 can create a more expansive look, while a narrower 1x4 might offer a finer texture. The orientation (horizontal or vertical) will also influence the visual impact and how light interacts with the wall surface.
Installation Considerations for Covered Patio Walls
Even in a covered setting, proper installation techniques are crucial. While a full rainscreen assembly might not be strictly necessary for a completely enclosed patio wall, ensuring adequate ventilation behind the wood is still beneficial. This helps manage any moisture that might accumulate and promotes air circulation, contributing to the wood's long-term stability.
Fastening methods should align with manufacturer recommendations for the specific profile. Face fastening with appropriate exterior-grade screws or nails is common for many profiles. For a cleaner look, some tongue and groove profiles can be blind-fastened through the tongue, concealing the fasteners.
Leave appropriate expansion gaps where the wood meets other materials or at corners. Although thermally modified wood exhibits increased stability, it still experiences some movement with changes in humidity and temperature. Consulting the specific product's installation guide for exact gap recommendations is advised.
Finishing and Maintenance for Lasting Beauty
Thermally modified wood can be left unfinished to weather naturally, developing a silver-gray patina over time. For covered patio walls, where direct UV exposure is reduced, this weathering process may be slower and less uniform than on fully exposed surfaces.
Alternatively, a finish can be applied to maintain or enhance the wood's initial rich brown color. Exterior-grade oils or stains formulated for wood siding are typically used. These finishes require periodic reapplication, the frequency of which will depend on the product type, exposure to indirect light, and local environmental factors.
Regardless of whether a finish is applied, routine cleaning to remove dust, cobwebs, and any mildew growth is beneficial. A mild soap and water solution, followed by a rinse, is usually sufficient. Avoid harsh chemicals or high-pressure washing, which can damage the wood fibers or strip finishes.
Project Example: Covered Patio Wall with NORX 1x6 T&G
Consider a covered patio with an interior wall section measuring 10 feet wide by 8 feet high. The goal is to clad this wall with NORX 1x6 thermally modified tongue and groove boards, installed horizontally. The nominal board width is 6 inches, with an actual coverage width of approximately 5.5 inches (accounting for the tongue and groove overlap).
To calculate the number of boards needed: First, determine the total linear feet required. For an 8-foot high wall, and boards installed horizontally, each course will be 10 feet long. If the coverage per board is 5.5 inches (or 5.5/12 feet), the number of courses needed is 8 feet / (5.5/12 feet per course) 17.45 courses. Round up to 18 courses to ensure full coverage.
With 18 courses, each 10 feet long, the total linear footage is 18 courses * 10 feet/course = 180 linear feet. If NORX 1x6 T&G boards are typically supplied in 10-foot lengths, you would need 18 boards. Always add a waste factor, typically 10-15%, for cuts, mistakes, and potential future repairs. For this project, adding 15% waste means 180 linear feet * 1.15 = 207 linear feet, or approximately 21 boards of 10-foot length.
This calculation assumes no significant openings (like windows or doors) within the wall section. For walls with openings, calculate the total area, subtract the opening area, and then divide by the coverage area of a single board, always rounding up to the nearest full board and adding waste.
Before you order
- Confirm the specific thermally modified wood species and profile are approved for wall applications.
- Verify the actual coverage width of the chosen profile for accurate material takeoff.
- Determine the desired aesthetic: natural weathering or a finished look (oil/stain).
- Plan for ventilation behind the wall cladding, even in covered areas.
- Select appropriate exterior-grade fasteners compatible with thermally modified wood.
- Account for expansion gaps at edges and corners.
- Consider the orientation of the boards (horizontal or vertical) and its visual impact.
- Obtain manufacturer installation guidelines for your specific product.
Confirm installation details, approved uses and warranty terms in the current instructions for the exact product and profile. Your installer should verify the substrate, structure and applicable project requirements.
This is a planning guide for projects in Pierre, SD. Ask our team to confirm availability, delivery to your ZIP code and which branch can support your order.
Questions to help you decide
Can thermally modified wood be painted for covered patio walls?
While thermally modified wood can accept paint, it is often chosen for its natural wood appearance. If painting is desired, use a high-quality exterior primer and paint system specifically formulated for wood. Ensure the wood is clean and dry before application, and follow the paint manufacturer's instructions for best results and longevity.
Is thermally modified wood heavy for wall applications?
The thermal modification process generally reduces the density of the wood slightly, making it comparable to or slightly lighter than its untreated counterpart. This makes it manageable for wall applications, similar to other wood siding products. Standard wall framing and fastening techniques are typically sufficient to support it.
How does thermally modified wood perform in humid environments, even if covered?
Thermally modified wood exhibits improved dimensional stability and reduced moisture absorption compared to untreated wood, making it a good choice for areas with fluctuating humidity. While covered patio walls offer protection, the wood's enhanced resistance to moisture-related movement helps mitigate potential issues like warping or cupping that can occur from ambient humidity.
Ready to Plan Your Covered Patio Wall Project?
Request a material quote with your project dimensions, exact profile, and ZIP code. We can help confirm current availability and service options for thermally modified wood, including NORX 1x6 Tongue and Groove or other suitable profiles. Explore our range of siding and cladding options, including MAXIMO Accoya, for your next outdoor project.
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