A Guide to Installing Hardie Board Siding

Hardie board siding, also known as fiber cement siding, is a popular alternative to traditional wood siding for homes. Made from a blend of cement, sand, and cellulose fibers, Hardie board is resistant to rot, fire, moisture damage, and termites. While more expensive upfront than wood siding, it’s long-lasting durability makes it a sound investment. Here’s an overview of how to installing Hardie board siding correctly:

Planning the Installation

Proper planning prevents problems down the road. Evaluate your home to determine the required materials. Calculate the square footage of each wall section to cover with Hardie board. Allow for a 10% overage for scrap pieces. Create diagrams marking stud locations to pre-plan seams and cuts. Determine starter strip placement and corners. Choose planks sizes based on wall height and visibility. Have all supplies and tools on hand before starting.

Preparing the Surface

Install Hardie board over plywood or oriented strand board (OSB) sheathing. The substrate must be at least 7/16” thick and code approved. Sheathing should be in good condition with no dry rot or deterioration. Remove any protruding nails and ensure the surface is flat. Prime the sheathing with latex primer before installing siding.

Cutting the Planks

Use a circular saw with a carbide tipped blade or a jigsaw to cut Hardie board planks to fit. Cut pieces upside down when possible to reduce breakage. For openings, measure and mark planks then cut with a jigsaw. Make all necessary cuts before fastening planks to walls. Wear safety goggles and a respirator when cutting to minimize dust.

Fastening the Boards

Use corrosive resistant siding nails to attach Hardie board planks to the studs. Nails should penetrate 1 1/4” into the studs. Space the nails 8” apart around the perimeter and every 12” in the field. Drive nails flush, not countersunk. Use a chalk line to keep courses straight and level. Maintain a minimum 1/8” gap between planks for expansion. For 16” wide planks, nail on each stud.

Installing Corners

For inside and outside corners, alternate lapping full planks in a staggered pattern. This avoids any vertical seams aligning. Use factory end joints at corners where possible for a tight fit. For boards meeting at corners, leave a 3/16” gap and caulk later during finishing. Flash horizontal seams with 15lb roofing underlayment.

Finishing Touches

Fill any gaps between planks with exterior grade caulk that matches the siding color. Use caulk sparingly for the best visual results. Paint all exposed cut edges with exterior latex paint to seal the cement board. Prime and paint the installed siding for extra weather protection and design.

Hardie board siding installation is straightforward with the right planning and materials. For a long lasting, low maintenance siding solution, choose trusted Hardie brand fiber cement. Follow these best practices for proper Hardie board installation.