Planning Thermally Modified Ash with Your Contractor: A Pre-Order Checklist

Confirming the Project Scope and Application

Thermally modified ash is a versatile material, suitable for a range of applications including cladding, ceilings, feature walls, and selected decking details. Before finalizing an order, confirm with your contractor the exact intended use for the material. This includes identifying whether it will be used vertically as siding, horizontally for a ceiling, or as a walking surface in specific decking applications.

Each application may have different requirements for profiles, fasteners, and substructure. For example, a rainscreen cladding system will have distinct needs compared to an interior feature wall. Clarifying the application ensures that the correct material profile and associated installation components are ordered.

Thermally modified ash offers a denser hardwood feel and a pronounced grain, making it suitable for high-visibility areas where aesthetic impact is important. Its improved stability in response to humidity changes makes it a candidate for both interior and exterior use. Ensure your contractor understands these characteristics and how they apply to the project's specific environmental conditions.

Verifying Profiles and Dimensions

Thermally modified ash is available in several profiles and nominal sizes, each suited for different applications. It is crucial to verify the specific profile and dimensions your contractor plans to use. Common profiles include S4S E4E End Match in nominal 1 × 6 Plus and 5/4 × 6, often used for siding, ceilings, and decking. Larger dimensions like S4S E4E in 2 × 4 and 2 × 6 are typically for decking and structural details. Trim and molding applications may use 1 × 10, 2 × 2, 2 × 4, or 2 × 6.

Work with your contractor to review the architectural drawings or project sketches, cross-referencing them with the available profiles. Confirm the chosen profile provides the desired aesthetic and functional properties, such as shadow lines for cladding or structural integrity for decking. Any discrepancies between design intent and available profiles should be resolved before ordering.

For example, if the design calls for a smooth, consistent surface, the S4S E4E profile may be appropriate. If a more traditional, interlocking appearance is desired for vertical applications, an end-matched profile could be considered, provided it aligns with the installation method.

Calculating Material Quantities: A Worked Example

Accurate material quantity calculation is critical to avoid delays and waste. This involves not only the total area but also accounting for cuts, waste, and specific installation patterns. Here’s a hypothetical example:

Imagine a wall cladding project requiring thermally modified ash with a nominal face width of 5.5 inches (for a 1x6 profile). The wall measures 12 feet high by 20 feet wide. The total area is 12 ft * 20 ft = 240 square feet.

First, convert the width of the material to feet: 5.5 inches / 12 inches/foot = 0.4583 feet. To cover 12 feet of height, you would need 12 ft / 0.4583 ft/board = 26.18 boards. Since boards must be full lengths, you'd round up to 27 boards for the height.

For the 20-foot width, if you are using standard 8-foot lengths, you would need 20 ft / 8 ft = 2.5 boards per horizontal row. This means each row would require three 8-foot boards, with a 4-foot offcut. If you plan to stagger joints, these offcuts might be reusable for subsequent rows, but careful planning is needed. For simplicity, if we assume non-reusable offcuts for this calculation, each 8-foot board covers 8 ft * 0.4583 ft = 3.66 square feet.

To cover 240 square feet, you would need 240 sq ft / 3.66 sq ft/board = 65.57 boards. Rounding up, you would need 66 boards. However, this is just area coverage. Because of cuts and the need for full lengths, the actual purchase quantity will be higher. Always add a waste factor, typically 10-15%, especially for projects with complex cuts or specific grain matching requirements. So, 66 boards * 1.15 (15% waste) = 75.9 boards. You would order 76 boards of the specified length.

Your contractor should provide a detailed material take-off, considering board lengths, waste factors, and specific cutting plans. Review this with them to understand assumptions about cuts and reusable offcuts.

Installation Details and Substructure

The performance and longevity of thermally modified ash depend significantly on correct installation. Discuss the proposed installation method with your contractor, including the type of fasteners, spacing, and the substructure. Thermally modified ash's improved moisture response contributes to its stability, but proper ventilation and drainage are still important for exterior applications.

For exterior cladding, a rainscreen assembly is often recommended to manage moisture effectively. This involves creating a cavity behind the cladding to allow for airflow and drainage. Ensure your contractor has a clear plan for this system, including furring strips or battens, insect screens, and flashing details.

If the material is for decking, confirm the joist spacing and any requirements for ventilation beneath the deck surface. For interior applications, ensure the substrate is suitable and any fire-rating requirements are addressed. Confirming these details upfront helps ensure the material is installed correctly and performs as expected.

Consider also the finish, if any, and how it will be applied and maintained. While thermally modified ash has a natural deep brown hue, it can be finished or allowed to weather naturally. Discuss this with your contractor and consider how this choice might affect the installation process and long-term care.

Delivery, Storage, and Jobsite Access

Logistics play a significant role in project success. Coordinate with your contractor regarding the delivery schedule, site access, and material storage. Thermally modified ash should be stored in a dry, protected area, away from direct sunlight and moisture, to maintain its stability before installation. Ensure there is adequate space on the job site for safe and proper storage.

Discuss who will be responsible for receiving the delivery, inspecting the material upon arrival, and moving it to the storage location. Any damages or discrepancies should be noted immediately. Clear communication on these points can prevent material handling issues and keep the project on schedule.

Consider the weight and length of the material. Longer lengths may require specific handling equipment or more personnel. Confirm with your contractor that they have the necessary resources to manage the delivery and on-site movement of the thermally modified ash.

Before you order

• Confirm the exact application (cladding, ceiling, decking, trim) for thermally modified ash.
• Verify the specific profile (e.g., S4S E4E End Match, S4S E4E) and nominal dimensions (e.g., 1 × 6 Plus, 2 × 4).
• Review the contractor's material take-off for accuracy, including waste factors and cut plans.
• Discuss the proposed installation method, including fasteners, spacing, and substructure (e.g., rainscreen, joist spacing).
• Clarify plans for any finishes or natural weathering, and associated maintenance.
• Coordinate delivery schedule, jobsite access, and on-site material storage with your contractor.
• Confirm responsibilities for material inspection upon delivery.
• Review any specific project documentation or manufacturer guidelines with your contractor.

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.

Questions to help you decide

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