Understanding Thermally Modified Wood for Outdoor Use
Thermally modified wood undergoes a process where wood is heated to high temperatures in an oxygen-deprived environment. This modification changes the wood's cellular structure, resulting in improved stability and reduced moisture absorption compared to untreated wood. These properties make it a suitable material for various exterior applications, including covered patio walls.
For covered patio walls, the 'covered' aspect is important. While thermally modified wood offers enhanced resistance to decay and insects, it is not impervious to all forms of moisture or direct weathering. A covered patio wall benefits from the material's stability, reducing the likelihood of warping or cracking due to humidity shifts, even if not directly exposed to rain and snow.
Selecting the Right Profile and Species
Thermally modified wood is available in various species, often including Spruce, Pine, and Ash, each offering distinct grain patterns and color variations. The thermal modification process typically darkens the wood, providing a rich, consistent tone. For covered patio walls, the choice of profile is primarily aesthetic, but also impacts installation and shadow lines.
Common profiles include tongue-and-groove, shiplap, and square-edge boards. Tongue-and-groove profiles, such as those found in NORX Siding and Cladding, can create a tight, seamless appearance, while shiplap offers a distinct overlap and shadow line. Square-edge boards allow for more visible spacing between planks, which can be a design choice. Consider the overall architectural style of your home and patio when selecting a profile.
You can explore options like our general selection of siding and cladding at /siding-and-cladding or specific brands such as NORX at /brands/norx.
Design Considerations for Covered Patio Walls
When designing covered patio walls with thermally modified wood, consider the orientation of the boards (horizontal or vertical), the desired finish, and how the walls will integrate with other elements of your patio. Horizontal installation can make a space feel wider, while vertical can draw the eye upwards, emphasizing height.
While thermally modified wood can be left unfinished to develop a natural silver-gray patina over time, applying a UV-protective finish or stain can help maintain its original color and offer an additional layer of protection. This is particularly relevant for walls that receive indirect sunlight. Ensure any finish selected is compatible with thermally modified wood and suitable for outdoor use.
Also, plan for proper ventilation behind the wall cladding, even in a covered application. A small air gap, often achieved with furring strips, helps manage any moisture and allows the wood to breathe.
Installation Planning and Substructure
Proper installation is crucial for the longevity of your thermally modified wood patio walls. The substructure, typically consisting of studs or furring strips, must be sound, plumb, and level. For covered patio walls, the substructure should also be designed to allow for an air gap behind the cladding, promoting drainage and air circulation.
Fastening methods should account for the wood's stability. While thermally modified wood is more stable than untreated wood, it still experiences minimal movement. Face fastening with corrosion-resistant screws is a common and secure method. Hidden fastening systems are also available for a cleaner aesthetic, but require careful planning to ensure adequate support.
It is important to follow the manufacturer's specific installation guidelines for your chosen profile and species. These guidelines will detail recommended fastener types, spacing, and any specific requirements for expansion and contraction. Consider consulting a professional installer familiar with thermally modified wood for complex installations.
Hypothetical Project Example: Covered Patio Wall for a Duluth Residence
Imagine a covered patio in Duluth, MN, with an existing concrete slab and a timber frame roof structure. The homeowner wants to clad two adjacent walls, each 10 feet long and 8 feet high, with thermally modified wood to create a warm, inviting outdoor room. They prefer a modern, clean look with subtle shadow lines.
For this project, they might choose NORX Thermally Modified Ash in a shiplap profile, with boards measuring 5.5 inches wide and 16 feet long. The total surface area for cladding is 2 walls x (10 ft x 8 ft) = 160 square feet. To account for cuts, waste, and starting/ending boards, a typical waste factor of 10-15% is advisable, bringing the required material to approximately 176-184 square feet. Since boards are 5.5 inches (0.458 ft) wide, each 16-foot board covers 0.458 ft * 16 ft = 7.328 square feet. Therefore, roughly 24 to 26 boards would be needed (184 sq ft / 7.328 sq ft per board = 25.1 boards, rounded up).
The shiplap boards would then be installed horizontally, starting from the bottom, with each board overlapping the one below. Corrosion-resistant fasteners would be used, concealed where possible or face-fastened according to the manufacturer's recommendations. A UV-protective oil would be applied to maintain the rich color of the Ash wood and provide protection against indirect sunlight.
Before you order
- Confirm the specific thermally modified wood species and profile (e.g., shiplap, tongue-and-groove) suitable for your design.
- Verify the dimensions of your covered patio walls and calculate the required square footage, adding a waste factor (typically 10-15%).
- Determine the desired orientation of the boards (horizontal or vertical) and how this impacts the visual flow of your patio.
- Decide on a finish: natural weathering for a silver-gray patina or a UV-protective oil/stain to maintain the original color.
- Plan the substructure, ensuring it is plumb, level, and allows for an adequate air gap behind the cladding.
- Select appropriate corrosion-resistant fasteners, considering visible versus concealed options.
- Review manufacturer installation guidelines for specific spacing, fastening, and detailing requirements.
- Consider the integration of the wood walls with other patio elements such as lighting, planters, or seating areas.
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 Duluth, MN. 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 used in a climate with harsh winters like Duluth, MN?
Yes, thermally modified wood is well-suited for climates with significant temperature fluctuations, including harsh winters. Its enhanced dimensional stability helps it resist warping, cracking, and checking that can occur with changes in humidity and temperature. For covered patio walls, the protection from direct snow and ice further contributes to its longevity.
Does thermally modified wood require maintenance?
While thermally modified wood is more durable than untreated wood, some maintenance is beneficial. If left unfinished, it will naturally weather to a silver-gray patina, which can be cleaned periodically. If a specific color is desired, applying a UV-protective oil or stain will help preserve the color and provide additional protection, requiring reapplication as recommended by the finish manufacturer.
Is thermally modified wood environmentally friendly?
The thermal modification process is typically chemical-free, relying only on heat and steam. This makes it an environmentally conscious choice compared to some chemically treated woods. The enhanced durability also means a longer lifespan, potentially reducing the need for replacement materials over time.
Request a Material Quote for Your Covered Patio Walls
Ready to enhance your Duluth, MN covered patio with thermally modified wood? Provide your project dimensions, desired profile, and ZIP code to request a material quote. We can help confirm current availability and service options for your project.
Request a material quote →