Cemplank lap siding, a fiber cement product manufactured by James Hardie, is a durable, cost-effective alternative to traditional wood siding. It is pre-primed, easy to install, and designed to withstand the rigors of the U.S. climate, including heavy rain, high humidity, and seasonal temperature variations. For homeowners and contractors seeking a long-term, low-maintenance exterior solution, Cemplank offers a compelling combination of strength, flexibility, and aesthetic appeal.
This article provides a detailed overview of Cemplank lap siding, including its composition, features, installation best practices, and key differences from other fiber cement products in the James Hardie lineup. By following the guidance provided, users can ensure a successful and code-compliant installation.
Overview of Cemplank Lap Siding
Cemplank lap siding is part of the broader fiber cement siding family, a category of building materials that combines cement, sand, and cellulose fibers to create a durable and weather-resistant cladding option. Unlike traditional wood siding, fiber cement products like Cemplank are resistant to rot, insect infestation, and fire, making them particularly well-suited for regions with challenging weather conditions.
Cemplank is marketed as a budget-friendly alternative to James Hardie’s premium HardiePlank line. While it shares the same core material composition, it is pre-primed rather than pre-painted, allowing for greater flexibility in color and finish choices after installation. This characteristic makes it an ideal choice for projects where customization is a priority.
The typical dimensions of Cemplank planks are approximately 5/16 inches thick, 8 to 8¼ inches wide, and available in 12-foot lengths. It offers a wood-grain (cedarmill) or smooth finish that mimics the appearance of traditional wood siding while providing the durability of fiber cement.
Key Features and Benefits of Cemplank Lap Siding
Cemplank lap siding is engineered to deliver long-term performance with minimal maintenance. Below are some of its key features and benefits, as outlined in the provided documentation:
- Rot and Moisture Resistance: Fiber cement is inherently resistant to moisture absorption, making it an excellent choice for humid or rainy climates such as those found in the Pacific Northwest.
- Fire Resistance: Cemplank is non-combustible, which helps reduce the risk of fire damage to buildings.
- Insect Resistance: Unlike natural wood, Cemplank is not vulnerable to termite infestations or wood-boring insects.
- Affordability and Long-Term Value: While Cemplank is a more economical option compared to premium fiber cement products, it still offers a long lifespan and strong performance, making it a cost-effective investment.
- Paint-Ready Surface: The pre-primed surface allows for easy and durable paint application, giving homeowners the ability to customize the color and finish to suit their preferences.
These attributes make Cemplank a popular choice for both new construction and remodeling projects, especially in regions where weather conditions can be harsh.
Differences Between Cemplank and HardiePlank
While both Cemplank and HardiePlank are fiber cement products manufactured by James Hardie, they differ in several key aspects:
- Finish and Warranty: Cemplank is pre-primed and requires painting after installation, whereas HardiePlank is available with a baked-on ColorPlus® Technology finish that offers enhanced fade resistance and paint adhesion. HardiePlank also comes with a 30-year limited warranty, while Cemplank typically offers a 10-year warranty with an additional 15-year pro-rated coverage.
- Aesthetic Options: HardiePlank provides a wider range of textures and styles, making it a more premium option in terms of appearance. Cemplank, on the other hand, is positioned as a more budget-friendly alternative with fewer styling options.
- Performance and Durability: Both products offer the core benefits of fiber cement, including resistance to rot, insects, and fire. However, due to its premium finish and extended warranty, HardiePlank is often considered to have slightly better long-term performance in challenging weather conditions.
Despite these differences, both products are built on the same durable fiber cement base, and both are designed to provide a strong, long-lasting exterior cladding solution.
Cemplank Lap Siding Installation Best Practices
Proper installation is essential for ensuring the performance and longevity of Cemplank lap siding. Below are key installation best practices drawn from the manufacturer's documentation and industry recommendations.
1. Preparation and Material Handling
Before beginning the installation, it is important to ensure that the building envelope is properly prepared. This includes installing a water-resistive barrier (WRB) such as Hardie® Wrap, which acts as a secondary defense against water intrusion. Flashing should also be installed behind butt joints to meet local building codes and provide additional protection. The flashing should be made from durable, waterproof material and overlap the course below by at least one inch.
When handling Cemplank planks, it is recommended to avoid repeating the texture pattern by working across the pallet rather than down. This helps ensure a more natural and visually appealing appearance. Two to four planks can be removed at a time, and material should be taken from adjacent stacks to maintain texture variety.
2. Layout and Alignment
To ensure accurate fastening and alignment, vertical chalk lines should be snapped on the water-resistive barrier at the center of every stud location. This helps guide the placement of the planks and ensures even spacing and alignment.
When installing the first course of siding, it is important to use a starter strip to maintain a consistent starting point. Starter strips can be made from fiber cement planks cut to size or manufactured specifically for this purpose. When cutting a starter strip, care should be taken to avoid marring or scratching the surface, especially if the siding has a protective laminate slip sheet.
3. Staggering and Fastening
Staggering the joints between planks is a key step in achieving a visually appealing and structurally sound installation. This helps distribute the load evenly and prevents water from pooling at the joints. A recommended method for staggering is to offset the joints by at least one-third of the plank width.
Fastening should be done with care to avoid over-tightening, which can cause warping or splitting. Fasteners should be spaced evenly along the length of the planks, following the manufacturer’s recommended spacing guidelines. It is also important to use fasteners that are compatible with fiber cement, as some types of screws or nails may react with the material over time.
4. Painting and Finishing
Since Cemplank is pre-primed, it must be painted after installation. The choice of paint should be based on the desired color and finish, as well as the climate conditions of the installation site. High-quality exterior paint with good adhesion properties is recommended to ensure long-term durability.
When painting, it is important to apply an even coat and allow sufficient drying time between coats. The paint should be applied in a way that covers all surfaces, including the edges and corners of the planks. It is also important to match the color of the joint flashing with the siding to maintain a cohesive appearance. Light-colored joint flashing should be used with light-colored siding, and dark-colored flashing should be used with dark-colored siding.
5. Maintenance and Long-Term Care
While Cemplank is designed to be low-maintenance, it still requires periodic inspection and cleaning to ensure optimal performance. Over time, dirt, mold, or mildew may accumulate on the surface, especially in high-humidity areas. A gentle cleaning with a mild detergent and water can help remove these buildups and restore the appearance of the siding.
It is also important to inspect the fasteners and flashing for signs of wear or damage. If any issues are found, they should be addressed promptly to prevent water intrusion or structural problems.
Code Compliance and Local Regulations
Local building codes may vary depending on the region, and it is important to consult with a local authority or building inspector to ensure compliance. In some areas, specific requirements may apply to flashing size, material, or installation methods. These requirements are often designed to address local weather patterns and structural needs.
James Hardie provides detailed installation instructions and best practices that are generally applicable across the U.S., but contractors should always verify that these recommendations align with local code requirements. In some cases, local codes may require additional measures, such as the use of specific fasteners or the inclusion of additional weather barriers.
Conclusion
Cemplank lap siding is a reliable and cost-effective fiber cement cladding option that offers the durability and performance of traditional wood siding without the associated maintenance and vulnerabilities. Its pre-primed surface allows for customization through painting, making it a versatile choice for a wide range of residential and commercial projects.
When installed according to manufacturer guidelines and local building codes, Cemplank provides a long-lasting, low-maintenance exterior solution that can withstand the challenges of the U.S. climate. By following best practices for preparation, layout, fastening, and finishing, contractors and homeowners can ensure a successful installation that meets both aesthetic and functional expectations.