Installing Fiber-cement Lap Siding

Installing fiber-cement lap siding.


This product comes in 12-foot lengths. These steps show 8-1/4-inch-wide boards installed with 7-inch exposures; you can choose narrower or wider boards and exposures. Layout and installation are generally the same as for wood lap siding. Here are the differences:

-- At the bottom of the wall, there is a starter strip rather than a water table board.
-- Because the material is very rigid, you can blind-nail the boards near the top, where the nailheads will be covered by the next course.
-- Because fiber-cement expands with rises in humidity, the boards should be cut 1/4 inch short so there is a 1/8-inch gap at each joint.

Like wood siding, the ends should be coated with primer before you install them. Cutting calls for different techniques and tools but is not difficult.


Working with a helper, about a day to install 600 square feet

Hammer or nail gun; miter saw; hand shears, grinder, or circular saw; speed square; tape measure; chalkline; drill; flat pry bar; level; caulking gun; utility knife; T-bevel; tin snips; staple gun; ladders and/or scaffolding

Measuring, laying out a job, cutting, driving nails

Cover the sheathing with building wrap and install trim boards and flashings as needed.

Fiber-cement siding, starter strip for the bottom, board to make story pole, strips of metal flashing or felt, staples, stainless-steel or galvanized siding nails, primer and paint

Step 1

Apply building paper, self-stick flashings at corners and around windows, and metal flashings as needed. Snap vertical chalklines indicating the centers of studs. Use a story pole to lay out the courses. Because there is no water table, you can probably raise or lower the bottom piece a couple of inches to achieve the course layout you desire. Make sure the bottom course will be at least 6 inches above grade and at least 2 inches above a driveway or sidewalk.

Step 2

To get the bottom board to flare out slightly, install a ripped piece of siding (shown) or a metal starter strip.

Step 3

Lay out the courses by marking the trim or snap chalklines indicating the tops of the boards (lines indicating the bottoms will be covered by the underlying pieces). To speed up installation, tack nails at these lines and butt the boards up to the nails when installing.

Step 4

Cut boards 1/4 inch short so that there will be a 1/8-inch gap at each end. Apply a generous coat of primer to all cut edges prior to installation. Apply a bead of caulk on the trim or abutting board before installing. Drive nails about 1-1/2 inches from the top of the boards where they will be hidden by the next course.

Step 5

At butt joints, slip a strip of felt or a short piece of 3-inch-wide metal flashing behind the boards. Alternatively apply strips of felt over all the studs.

Step 6

Fiber-cement is prone to cracking, so drill pilot holes first wherever you will drive a nail less than 2 inches from the end.

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