Understanding Thermally Modified Wood for Wall Applications
Thermally modified wood undergoes a high-temperature treatment process that alters its cellular structure. This process reduces the wood's ability to absorb moisture, which contributes to increased dimensional stability and resistance to decay. For covered patio walls, where full weather exposure is mitigated but environmental shifts still occur, these properties can be beneficial.
The modification process also imparts a rich, darker tone to the wood, often resembling exotic hardwoods. This color is consistent throughout the material, meaning that minor scratches or cuts are less noticeable than with surface-stained wood. While the initial color is appealing, it's important to understand that, like all natural wood, thermally modified wood will gradually weather to a silvery-gray patina if left unfinished and exposed to UV light.
Selecting the Right Profile for Covered Patio Walls
The profile of the thermally modified wood planks significantly influences both the appearance and the installation method of your covered patio walls. Common profiles include tongue-and-groove, shiplap, and square-edge boards.
Tongue-and-groove profiles create a tight, interlocking fit, which can be advantageous for a clean, uniform look and can help conceal fasteners. Shiplap offers a distinctive overlapping joint, creating shadow lines that add visual interest. Square-edge boards, when installed with a consistent gap, can provide a more contemporary, open aesthetic. For covered patio walls, the primary consideration for profile often leans towards visual preference and ease of installation, as the direct weather protection reduces the need for extensive rainscreen detailing.
Consider the overall design of your patio and home when selecting a profile. A rustic aesthetic might benefit from a wider shiplap, while a modern design could use narrower, square-edge boards with minimal gaps.
Finishing Options and Appearance Over Time
While thermally modified wood is naturally resistant to decay, applying a finish is crucial if you wish to maintain its original rich color. UV exposure will cause the wood to gradually lighten and eventually turn a silvery-gray. Clear, UV-inhibiting oils or stains can help preserve the initial color and enhance the wood's natural grain. These finishes typically require periodic reapplication, depending on the product and exposure to indirect sunlight.
If you prefer the weathered look, no finish is required. The wood will naturally age to a soft gray, which can complement many outdoor design schemes. This low-maintenance approach is a common choice for those seeking a natural, rustic appearance. Ensure that your choice aligns with your long-term aesthetic goals and willingness for maintenance.
Attachment Methods and Substructure Considerations
Proper attachment is key to a stable and long-lasting covered patio wall. For thermally modified wood, fasteners should be corrosion-resistant, such as stainless steel screws. Hidden fastening systems are often preferred for a cleaner appearance, especially with tongue-and-groove or shiplap profiles. Face fastening is also an option, but the fastener heads will be visible.
The substructure behind the thermally modified wood needs to be sound and provide adequate support. This typically involves vertical furring strips or a solid sheathing material. Even in a covered application, ensuring proper ventilation behind the wood can help equalize moisture content and further enhance dimensional stability. Maintain a small gap at the bottom of the wall for drainage and airflow, and at the top for ventilation, even if minimal.
Worked Example: Designing a Covered Patio Wall
Consider a hypothetical covered patio in Cheyenne, WY, with one main wall section measuring 12 feet wide by 8 feet high. The homeowner desires a shiplap profile for a contemporary look, with an initial preference for maintaining the natural dark tone. They plan to use 1x6 (nominal) thermally modified wood shiplap boards, which are typically 5.5 inches wide in actual dimension.
To calculate the approximate number of boards needed: The wall height is 8 feet, or 96 inches. Each board covers 5.5 inches. 96 inches / 5.5 inches per board = approximately 17.45 boards. Since boards are typically sold in specific lengths (e.g., 8, 10, 12, 16 feet), we'd need to select lengths that minimize waste for the 12-foot width. If using 12-foot boards, 18 boards (rounded up) would be needed to cover the height. For a 12-foot length, 18 boards x 12 feet/board = 216 linear feet. However, due to cuts and potential waste, it's prudent to add 10-15% for cuts and waste, bringing the estimate to around 238-248 linear feet. This would translate to 20-21 boards of 12-foot length.
For finishing, a UV-inhibiting oil would be recommended to preserve the color. This would need to be applied after installation and periodically thereafter.
Before you order
- Determine desired aesthetic: Natural weathered gray or maintained original color?
- Select preferred profile: Tongue-and-groove, shiplap, or square-edge?
- Verify substructure readiness: Is it stable and prepared for cladding attachment?
- Choose appropriate fasteners: Hidden clips or visible corrosion-resistant screws?
- Plan for ventilation: Ensure minimal airflow behind the planks, even in covered areas.
- Consider maintenance: Are you committed to periodic finishing if color retention is desired?
- Measure accurately: Calculate linear footage and account for waste (10-15% is common).
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 Cheyenne, WY. Ask our team to confirm availability, delivery to your ZIP code and which branch can support your order.
Questions to help you decide
Does thermally modified wood require a finish for covered patio walls?
No, a finish is not strictly required for durability. Thermally modified wood is naturally resistant to decay and stable. However, if you want to maintain its original rich, darker color, you will need to apply a UV-inhibiting oil or stain periodically. Without a finish, the wood will naturally weather to a silvery-gray over time due to UV exposure.
Can thermally modified wood be installed directly onto existing wall framing?
While it can be installed onto framing, it is generally recommended to use furring strips or a solid sheathing with a weather-resistant barrier behind the thermally modified wood, even in covered applications. This provides a level surface, allows for proper fastening, and creates a small air gap for ventilation, which can help with moisture management and stability.
What are the common dimensions available for thermally modified wood siding?
Thermally modified wood for wall applications is commonly available in various nominal widths, such as 1x4, 1x6, and 1x8, with actual dimensions being slightly smaller. Lengths typically range from 8 feet to 16 feet. Specific profiles like tongue-and-groove or shiplap will have a defined coverage width that is less than their overall actual width. Always confirm actual dimensions and available lengths when planning your project.
Ready to Plan Your Covered Patio Walls?
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