Fiber Cement Siding Installation Tips

Close up of a condo with fiber cement siding

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Fiber cement siding is not that difficult to install if you have some basic information. One of the most essential facts and obvious is to follow your fiber cement manufacturer’s instructions that have been formulated based on their product and specifications.

Tools and Materials

Fiber cement siding must be cut face down with a diamond tip blade. When an irregular cut is needed, a jigsaw equipped with a medium or coarse-grit carbide blade can be used. A diamond jigsaw blade will be useful too.

Prep the Surface

Make sure the wall or surface is prepared to receive the cement siding. Make sure that the windows, doors, and openings have been flashed all around their perimeter. Also, check if your manufacturer requires a weather-resistive barrier.

Hanging Fiber Cement Siding

Nails used to hang fiber cement siding shall penetrate at least 1 ¼” into the studs or the structural framing. Remember that the siding is hard so be sure the nails are located at the right place before driving them. If the cement siding is to be installed over wood sheathing (7/16’ OSB or ½” plywood at a minimum), it is recommended to use a 6d nail. Sometimes, if you are trying to drive the nails and you are having problems, you can pre-drill the holes to facilitate the job.

Siding can be installed over wood and metal studs. These studs shall be a minimum 20 gauge, 3-5/8" C-studs. Fasteners shall be flush to the surface material. Do not countersink or angle fasteners. When blind nailing, place nail 1" down from the top of the board, and when face nailing, place nail 3/4" up from the bottom.

Insulation Used With Fiber Cement Siding

It is important that the insulation product used when installing fiber cement siding will be able to level the wall and align each siding panel properly. When you add insulation to the siding, the customer’s energy bill will be reduced too, so you might want to highlight this as an additional benefit for your client. Fiber cement siding should be installed over plywood, OSB, or sheathing.

Be sure that the siding installed is dry. Otherwise, it might shrink at butt joints. When sheathing is the preferred surface that will receive the fiber cement siding or any other fragile substrate, be sure to pre-drill the holes at corners to prevent accidental damages. Building codes will usually require installing siding over water-resistant barriers and nailed into the studs every 16 or 24 inches.

Fiber Cement Siding Tolerances and Gaps

When installing fiber cement siding be sure to leave at least ¼” clear space between the siding and the flashing vertical siding should be installed and attached to the structural framing when a non-structural sheathing, gypsum board or foam-type sheathing are used.

When you are getting close to the final grade, leave at least 6" between the bottom of the siding and finish grade, and a minimum of 1 ½” above rooflines and decks. Fiber cement siding shall have a 1/8" gap between trims of windows and doors. If you need to cut cement siding a 100% acrylic latex primer must be used to reseal the surface. Install all butt ends and joints in contact with one another.

Finishing Fiber Cement Siding

Be sure to caulk, paint, or finish fiber cement siding following manufacturer's recommendation. By doing this, you will be making sure that the siding is ready to withstand changing weather conditions. Caulk around windows, doors, trims, and self-flashing penetrations.

Storage and Care for Cement Siding

Fiber cement siding should be kept covered while not been installed on a clean, flat and leveled surface. The siding must be protected from direct exposure to weather that could damage the cement siding before it is installed. If you need to move siding pieces, be sure to carry them by their narrow edge and support it when you cut larger pieces.