In our continuing series on exterior siding, today we’ll be digging into another option that has grown in popularity due its durability and ability to mimic the “real thing”(in this case, wood) without taking a hammer to your bank account. Since the early 2000s, fiber cement planks have become an increasingly frequent choice among builders searching for a solid alternative when deciding on the ideal siding for their residential projects. Here are a few reasons why:
- As mentioned above, it’s less expensive than real wood siding, though more costly than vinyl.
- It’s available in a variety of colors, widths, and authentic textures, making it hard to distinguish between natural lap siding. Additionally, it can be painted over if you can’t find a color to suit your tastes.
- With proper care, it is known to last up to 50 years.
- It’s made from Portland cement coupled with silica and a small amount of wood fiber that acts as a bonding agent. Unlike genuine wood or compressed wood fiber, this combination of materials makes fiber cement siding more resistant to wear (e.g., cupping, splitting, cracking, and rotting).
- It won’t burn, and wood-destroying insects aren’t particularly fond of it either.
Sounds like the perfect solution, right? Not exactly. Fiber cement siding still requires maintenance and homeowner vigilance to make sure it stands up to the weather and performs as it should. Similar to common defects that tend to plague brick and artificial stone veneer, faulty installation is most often at the root of problems that your home inspector may find during the exterior portion of a complete inspection. Some problems are considered relatively simple fixes while others require intrusive and costly repairs.
Here is a brief checklist of issues the certified home inspectors at A-Pro have found with fiber cement siding:
Incorrect Nailing: Ambitious do-it-yourselfers or even professional contractors who don’t follow specific manufacturer recommendations for fastening fiber cement boards are asking for trouble. Nails should only be driven at the board’s top edge, with exceptions made when installing in high-wind areas. This helps prevent cracking that can result from locating fasteners where they’re not supposed to be. Further, the nails should be hidden, of a proper length to penetrate wood at a recommended depth, driven straight rather than at an angle, the correct type, and driven flush against the surface. In addition to cracks, your inspector may discover loose boards that were the result of nails that did not hit studs, over-driven nails, or too few nails used to fasten the board. Nails driven too close to the top edge are another possible cause of looseness. Another common cause of failure is installing fiber siding when it is too wet, which may lead to shrinkage gaps that will be pointed out by the inspector.
Flashing: We don’t mean to sound like a broken record, but we can’t stress this enough: proper flashing is essential when installing all kinds of siding. In this case, water can get behind the fiber cement siding and rot the wood structures below or become trapped and accelerate damage to the siding itself. Examples include missing kick-out flashing at roof/wall junctures, siding that runs directly into metal flashing (a recommended gap is required), flashing that isn’t sloped to effectively drain water, and absence of head flashing at windows and doors.
Your inspector will also look for signs of water penetration, such as blistering paint and fungal growth appearing through gaps (an indicator that the house wrap is retaining moisture, making it susceptible to such growth).
Gaps: Unsightly gaps at the butt joints provide an unpleasant invitation for wind-driven rain to penetrate the surface and cause exterior damage. Further, these openings may reveal another common installation defect—lack of back flashing (either house wrap or metal flashing) at butt joints. Un-caulked openings at vertical trim joints can also lead to similar water damage. Other problems include unsealed openings at wall penetrations.
Your inspector may also observe buckling, curling at butt joints, and what appears to be impact damage to fiber cement siding, which is more vulnerable than vinyl siding to suffering breakage after being struck by a fallen limb or other object. While more resistant to weathering than real wood, fiber cement siding may decay over time due to water exposure. This deterioration will end up in the home inspection report. As we’ve discussed in previous siding posts, insufficient clearances (between siding and the ground, trim, horizontal flashing, roofing, etc.) will also be noted.