Using Thermally Modified Ash in a Wall Retrofit

Initial Wall Assessment: Inspecting for Water Damage

The first step in any wall retrofit is a comprehensive assessment of the existing structure. Water damage is a primary concern, as it can compromise the structural integrity of the wall and lead to issues like mold and rot. Look for visible signs of water intrusion such as staining, discoloration, peeling paint, or warped materials. Pay close attention to areas around windows, doors, and rooflines, as these are common points of water entry.

Beyond visual inspection, consider using a moisture meter to detect hidden moisture within the wall cavities. Elevated moisture readings can indicate active leaks or areas where water has accumulated. Document all findings, including photographs and measurements, to inform the scope of necessary repairs before any new material is installed.

Evaluating Substrate Integrity and Repair Needs

Once water damage is identified, the next step is to evaluate the integrity of the substrate. This includes the sheathing, framing, and any existing insulation. Soft spots, crumbling material, or pest damage all indicate a compromised substrate that requires repair or replacement. For wood-framed walls, check for rot in studs, plates, and headers. For masonry walls, inspect for spalling, cracks, or mortar deterioration.

Any damaged sections of the substrate must be repaired or replaced to provide a sound base for the new Thermally Modified Ash siding. This might involve removing sections of existing sheathing, reinforcing framing, or performing masonry repairs. Addressing these issues proactively prevents future problems and ensures the longevity of your retrofit.

Choosing Thermally Modified Ash Profiles for Wall Applications

Thermally Modified Ash offers a hardwood presence with a pronounced grain, making it a suitable choice for high-visibility applications like exterior cladding. It is available in various profiles, including S4S E4E End Match in nominal sizes such as 1 × 6 Plus and 5/4 × 6, which are specified for siding and ceiling applications. The S4S E4E profile in sizes like 1 × 10, 2 × 2, 2 × 4, and 2 × 6 can also be used for trim and molding.

When selecting a profile, consider the desired aesthetic and the architectural style of your property. For a sleek, modern look, a narrower board might be preferred, while wider boards can create a more traditional or rustic feel. The end-matched profiles can simplify installation by allowing boards to be joined between studs, potentially reducing waste. Always confirm the specific profile and installation system for your chosen application.

Lumber Plus offers Thermally Modified Ash. You can explore available profiles at: /thermally-modified-wood/ash

Planning for Ventilation and Rainscreen Systems

For exterior wall retrofits, incorporating a rainscreen assembly is often recommended. A rainscreen system creates a drained and vented air gap between the exterior cladding (Thermally Modified Ash) and the weather-resistive barrier. This gap allows moisture that penetrates the cladding to drain away and promotes drying of the wall assembly, significantly improving durability and preventing moisture-related issues.

Designing an effective rainscreen involves selecting appropriate furring strips or a proprietary rainscreen mat. Ensure that continuous ventilation is provided at the top and bottom of the cladding system to allow for airflow.

Hypothetical Retrofit Example: A 12-foot by 20-foot Wall

Consider retrofitting a single exterior wall measuring 12 feet high by 20 feet wide. The total wall area is 240 square feet. After inspection, you determine that the existing sheathing is sound, but a new weather-resistive barrier and furring strips for a rainscreen system are needed. You select Thermally Modified Ash in an S4S E4E End Match profile, nominal 1 × 6 Plus.

The nominal 1 × 6 Plus profile typically has a face width of approximately 5.5 inches. To calculate the number of linear feet needed, divide the total area by the face width (in feet): 240 sq ft / (5.5 inches / 12 inches/foot) = 523.6 linear feet. Accounting for cuts, waste, and a 10% contingency, you would need approximately 576 linear feet of material.

If the boards are available in 8-foot lengths, you would need 576 linear feet / 8 linear feet/board = 72 boards. If they are available in 16-foot lengths, you would need 576 linear feet / 16 linear feet/board = 36 boards. Always confirm actual board lengths and adjust calculations accordingly. Remember to factor in trim pieces for corners and openings, which might require additional material from the 1 × 10 or 2 × 2 profiles.

Before you order

• Thoroughly inspect existing wall for water damage, rot, and pest issues.
• Evaluate the integrity of the substrate (sheathing, framing) and plan necessary repairs.
• Determine if a rainscreen system is required or beneficial for your climate and wall assembly.
• Select the appropriate Thermally Modified Ash profile (e.g., S4S E4E End Match 1 × 6 Plus) for your aesthetic and application.
• Calculate linear footage of cladding, accounting for waste, cuts, and trim pieces.
• Plan for proper fastening methods suitable for thermally modified wood.
• Consider the desired finish: allow to weather naturally or apply a protective coating.
• Review local building codes and ensure your retrofit plan complies.

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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