NewTechWood Outdoor Surfaces and Rainscreen Assemblies: Specify the Whole Wall

Understanding the Rainscreen Principle

A rainscreen cladding system works on the principle of separating the outer cladding layer from the primary weather barrier of the building. This separation creates a drainage cavity, allowing any water that penetrates the cladding to drain away freely before reaching the structural wall. The cavity also promotes ventilation, helping to dry out any moisture that might accumulate.

This approach differs from barrier walls, where the cladding itself is the primary defense against water. While NewTechWood Outdoor Surfaces offer low-maintenance and wood-look aesthetics, incorporating them into a rainscreen assembly provides an additional layer of moisture management, contributing to the overall resilience of the building envelope.

Key Components of a NewTechWood Rainscreen Assembly

A complete rainscreen assembly with NewTechWood Outdoor Surfaces involves several integrated components:

1. **Exterior Cladding (NewTechWood Outdoor Surfaces):** This is the outermost layer, providing aesthetic appeal and initial protection against weather. NewTechWood offers various wood-look composite profiles for this purpose. (S1)

2. **Drainage Cavity:** This is the air space behind the cladding, typically 3/8 inch to 1 inch deep, created by furring strips or a drainage mat. This cavity allows water to drain and air to circulate.

3. **Furring Strips:** These vertical or horizontal strips are typically wood or metal, installed over the weather barrier to create the drainage cavity and provide a fastening surface for the NewTechWood cladding.

4. **Weather Barrier (WRB):** This is the primary moisture control layer, applied directly to the sheathing. It prevents water that has passed through the cladding and drainage cavity from entering the wall assembly. Common types include house wraps or fluid-applied membranes.

5. **Sheathing:** The structural substrate, typically plywood or OSB, to which the weather barrier is applied.

Designing the Drainage and Ventilation

Effective drainage and ventilation are crucial for a rainscreen system. The drainage cavity must have unobstructed pathways for water to exit at the base of the wall and for air to circulate. This typically involves insect screens or specialized vents at the bottom and top of the cladding system.

Consider the orientation of your NewTechWood profiles. While NewTechWood can be installed horizontally or vertically, the furring strip layout will vary. Vertical cladding often requires horizontal furring strips to create the cavity, while horizontal cladding typically uses vertical furring strips. Ensure that the cavity remains continuous and clear of obstructions.

Worked Example: Designing a Rainscreen Wall Section

Let's consider a hypothetical 10-foot by 10-foot wall section on a residential project, aiming for a rainscreen assembly with horizontally installed NewTechWood Outdoor Surfaces. We'll assume a standard 16-inch on-center stud framing.

1. **Sheathing:** The wall will have 1/2-inch OSB sheathing.

2. **Weather Barrier:** A continuous, self-adhered weather barrier membrane will be applied over the sheathing.

3. **Furring Strips:** To create a 3/4-inch drainage cavity and support the horizontal cladding, we'll use 3/4-inch by 1 1/2-inch vertical pressure-treated wood furring strips. These will be spaced at 16 inches on center, directly over the wall studs. For a 10-foot wide wall, this means approximately 8 vertical furring strips (10 ft / 1.33 ft/strip = 7.5 strips, round up to 8). Each strip is 10 feet long, so 8 x 10 = 80 linear feet of furring.

4. **NewTechWood Cladding:** The NewTechWood cladding will be installed horizontally, fastened to the furring strips according to manufacturer guidelines. Assuming a nominal 6-inch wide NewTechWood profile, a 10-foot high wall would require approximately 20 courses (10 ft / 0.5 ft/course = 20 courses). Each course is 10 feet long, so 20 x 10 = 200 linear feet of cladding.

5. **Ventilation:** A continuous insect screen will be installed at the bottom of the wall, behind the lowest course of cladding, and a similar screened vent strip at the top to allow for air intake and exhaust.

This example illustrates the layers and the need to calculate material quantities for each component, not just the visible cladding.

Product Selection and Compatibility

When specifying NewTechWood Outdoor Surfaces for a rainscreen, confirm the specific profile and its fastening requirements. (S1) Some profiles may be designed for specific clip systems, while others are face-fastened. The chosen fastening method will influence the furring strip material and dimensions.

Also, consider complementary products. The effectiveness of a rainscreen relies on the integrity of all its components. Ensure that your weather barrier, flashing, and furring materials are compatible and designed to work together in a complete system. Consult the NewTechWood product documentation for recommended installation practices and any specific requirements for rainscreen applications. (S1)

Before you order

• Is a rainscreen assembly required or desired for moisture management and durability?
• What depth will the drainage cavity be (typically 3/8 inch to 1 inch)?
• What type of weather barrier will be used (e.g., house wrap, self-adhered membrane)?
• What material and dimensions will the furring strips be (e.g., treated wood, metal)?
• How will the NewTechWood cladding be fastened to the furring strips?
• What are the ventilation requirements at the top and bottom of the wall (e.g., insect screens, vent strips)?
• Are all flashing details around windows, doors, and penetrations integrated into the rainscreen design?
• Have material quantities been calculated for all layers: sheathing, weather barrier, furring, and NewTechWood cladding?
• Have any local building codes or specific climate considerations been addressed?

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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