How to Install Fiber-cement Panels
On most walls, we attached the siding to furring strips, which also served to hold in place the 4 inches of rigid foam we added to the outside of the walls. Because foam compresses, before installing the siding, we used a string line to ensure the furring strips were in plane [2]. This was especially important with the large fiber-cement panels, which are less flexible than lap siding.
The 4-foot-wide panels are factory-painted and mounted to a system of aluminum tracks fastened to the wall. The track, which is also factory-painted, is a geometric part of the panel design. Components include outside corners [3], inside corners, vertical butt joints, J-channel, and a Z-channel that allows for drainage at horizontal joints.
On the retrofitted sections of the house, we mounted the track to furring strips [4] but the more typical installation is directly over sheathing. That was the case on this house at the bump-out, which was new construction built using ZIP System sheathing instead of rigid foam and furring strips.
Step by Step
• We began with a single piece of outside corner track fastened vertically to the wall sheathing. The track spaces the siding panels off the wall sheathing about 1/8 inch, which creates a capillary break behind the siding. (In other parts of the building, we used J-channel where the fiber-cement was butted against a trim board.) We slid the long edge of the first panel into the track [5], made sure it was properly positioned up off the roof, and screwed it in place through pre-drilled holes [6].
• To prepare for the next panel, we slid a piece of track over the other vertical edge and fastened it to the sheathing. To get the long-point dimension, we measured the in-place panel [7], then added ½ inch because the tops of the panels
tuck under a fascia that rims the top of the bump-out. We got the short-point dimension by measuring to a vertical line snapped 4 feet away.
• At the cut station on the ground, we cut the panel to size and pre-drilled for fasteners. Because the roundhead stainless steel fasteners were designed to be visible, we laid
out the fasteners on a grid to ensure they would be regularly spaced and visually aligned.
• Back at the wall, the crew tucked the top of the panel under the fascia, then slid the long edge into the track against the in-place panel. The final step before fastening was to lift the panel until the bottom edge was flush with the in-place panel [8].
where the fiber-cement panels terminated at trim boards.
Although panels can be installed on a 4-foot module, on this project we located horizontal and vertical joints to create a geometric pattern oriented around the position of the windows [9].