HardiePlank Siding Installation

June 26th, 2020 / Premier Building

HardiePlank Siding – Everything You Need to Know

HardiePlank lap siding is a pre-primed, cement-fiber siding that provides high performance and an attractive appearance. It is resistant to water absorption, which helps prevent damage from swelling, cracking or mold. HardiePlank lap siding is also hail-damage resistant and non-combustible. This siding is offered with an exclusive finish, better known as ColorPlus Technology, which uses a multi-coating procedure to oven-bake color onto the siding. This process helps to prevent color fading from high UV levels. HardiePlank lap siding was engineered with a focus on providing an extra level of defense against various climatic issues. The HZ5 product line is the result of multiple generations of testing and designing. Its substrate composition is ideal for structures located in climates with snow, ice, freezing temperatures and variations in seasonal temperature. HardiePlank HZ5 lap siding also features a drip edge to assist with water control in conditions related to these climates.

HardiePlank Siding Installation

HardiePlank siding. A 1-1/4” piece of siding can be ripped off of full or partial planks and used to make these strips. A starter strip underneath the initial course is required in order to set the siding at the correct angle. This will also form a drip edge at the siding’s bottom. The starter strip should be installed over the weather-resistant barrier, and flush with the sheathing’s bottom edge. Leave intermittent gaps in the starter strip to help drain any moisture that may have accumulated behind the siding.

Ensuring the initial starter course is set up properly is vital to the installation process. The starter course should begin at the lowest point of the building, within the bounds of required clearances. It should be properly aligned using a level, and the course’s straightness should be checked periodically as installation continues along the wall. Drywall shims can help correct flatness over insulation, or other exterior factors. Place the lower edge of the course at a minimum of ¼” underneath the starter strip’s edge and secure it. Next, run siding over to the HardieTrim board while making sure to leave a 1/8” gap in-between the trim and the siding. The bottom of the trim should generally be flush with the bottom of the siding, but if preferred, the trim may hang below the siding. However, the siding should never extend below the trim. A level, speed square or framing square may be used to match up the plank course heights on each side of a corner.

Blind nailing is the generally recommended technique for installing HardiePlank lap siding. This results in every course covering the fasteners on the course underneath it to give the installation a superior look. It is recommended to install fasteners 1” from the plank’s top edge. Fasteners should not be placed any closer than 3/8” from the plank’s ends. The HZ5 product line was designed with a nail line etched into it that can help guide nail placement.

Additional lengths of HardiePlank lap siding need to be butt jointed for any walls exceeding 12 feet in length. Between consecutive courses, butt joints should be spaced apart by one stud bay for 24” o.c. framing, or a minimum of two stud bays for 16” o.c. framing. The joints should ideally be staggered to prevent noticeable patterns. Using this technique, one course’s cut-off piece becomes the starter piece of the course above. This in turn makes the process faster and easier, while making more effective use of materials. Butt joints should land on studs. It is not recommended to land them in-between studs. Both sides of a joint should lie in the center of a stud, with 3/4” landing space on each side. Butt joints should also avoid being placed directly below or above doors or windows. Ideally, finished ends should be placed at butt joints where siding encounters trim, corner, door or anywhere else the joint would be caulked. For products using the patented ColorPlus Technology finish, a color-coded edge coater will help seal any cut ends.

Joint flashing is recommended over other joint treatment options. Flashing behind joints gives an added level of defense against water entry. Flashing material must not react to cement products and must be waterproof, such as water resistant barriers or coil stock. A 6” wide flashing material that overlaps the course underneath by 1” is recommended, although building codes may require alternative sizes.

When the first course of HardiePlank siding is set on the wall, proceed with fitting additional courses using full 12 foot pieces, or until an external opening (such as a door or a window) disturbs the course’s path. Ensure that all cut edges are sealed, and notch planks to fit around any doors or windows as needed.