Sample wall section of fiber cement panel solution with expressed trim and fasteners.

Used as a siding or sheathing, this gridded surface becomes part of the envelope design. Building scientist, Joseph Lstiburek, states, "Where cladding systems such as fiber-cement siding shine is that they allow air circulation and don't inhibit drainage. That's very different from a stucco assembly or a brick veneer." As seen in a typical wall section, the fiber cement panel is placed along with the exposed seams and is adhered to the weather barrier. These panels should be applied to a flat wall surface and unless otherwise instructed must be installed in a manner such that the panel joints are vertical and horizontal and not installed at an angle. All panels are open at the bottom edge to allow for proper flashing and drainage.

Manufacturers provide technical data for installation of their particular product, however, some standard guidelines for fiber cement panels installed in a grid system include:

• Panels can be installed over braced wood, steel studs or furring spaced a maximum of 16" on center. Irregularities in framing and sheathing can mirror through the finished application. They should be installed over the weather barrier and detailed as part of an integrated weather resistant wall system.

• Panels can also be installed over foam insulation/sheathing up to 1" thick. When using foam insulation/sheathing avoid over-driving fasteners. Over-driving fasteners can result in dimpling of the siding due to the compressible nature of the foam insulation/sheathing.

• Panels should be part of a well detailed wall system with flashing and require a water-resistive barrier in accordance with local building code requirements.

• Panel installation should maintain a minimum of 1/4" clearance between the bottom of any horizontal trim in order to provide proper drainage and provide gaps as required at end caps.

• Window installations should follow window manufacturers' installation instructions to ensure that the window is properly flashed and sealed to prevent any water penetration. Panels are recommended to have a minimum of ¼" to ½" clearance to provide enough room for window flashing at the head of the installed window.

• It is important to separate panels from any standing water, for example, where a sloped roof intersects with a vertical wall, kick out flashing of sufficient length and angle to direct the water running down the roof away from the siding should be used.

• Panels should be installed with a minimum 6" clearance to the finished grade on the exterior of the building or in accordance with local building codes.

• Installers should maintain a 2" clearance between fiber cement products and roofs, decks, paths, steps and driveways and adjacent finished grades must slope away from the building to prevent panel contacts with standing water.

When used as part of a poured insulated block wall, the professional needs to review the "pull" strength of the block nailing surfaces. Poured insulated block manufacturers have tests verifying pull strength values of nailing for wood, when installing fiber cement on these systems, the pull strenght should be equal or better to the pull strength listed for wood siding.

Fiber cement panels are impact resistant, and should be detailed to fasten flat on sheathing. New panels are a heavier, 7/16" thick surface instead of the thinner 5/16" panel. A thicker panel is more durable, and was engineered to increase impact resistance and provide an even longer lasting sustainable surface. Some panels can be installed to achieve the MIAMI − DADE rating for large and small missile impact and can be used in hurricane prone climates. Fiber cement panels are non-combustible in accordance with ASTM 136.

Design to climate - an engineered sustainable solution

Building materials interact with their climate zone. Leading manufacturers allow design professionals to specify panels to respond to a variety of weather conditions providing engineered products for as many as eight individual climatic variables. The professional can provide the zip code for their project in order to specify the correct weather resistant material. For example, by choosing a fiber cement product engineered for the freeze/thaw cycle, the professional can resist damage from snow, ice and moisture so as to maintain dimensional stability in the product. In the south, fiber cement can be engineered to resist hurricane-force winds as well the cracking, splitting rotting and swelling that can occur in very humid climates. In particular, finishes for both the aluminum grid as well as the panel surface, should be specified to assure that there is no particular damages due to climate, in particular, coastal areas with high salt concentrations in the air.

Field installation and sustainable construction management

Fiber cement panels with expressed joints are ordered by the professional and installed in the field by builders. Other than a special carbide tipped blade or fiber cement shears, tools are affordable and easy to use. Sustainability includes the awareness of construction management and with fiber cement panels the rules are clearly listed on product installation sheets. The primary issue is the control of construction dust.

Preferably, panels should be cut outdoors and the cutting station positioned that wind will blow dust away from the user and others in the working area. Installers can use either fiber cement shears or special carbide - tipped blades in a circular saw with a HEPA vacuum. Manufacturers also suggest that NIOSH-approved respirators are approved to reduce dust particals from causing lung damage during construction as part of a sustainable construction management procedure.

Since panels are manufactured off site, they arrive onsite and can be postioned and cut with very little construction waste. The panels are often pre-drilled which has the benefits of saving construction labor and materials as well as an opportunity for the control of the aesthetic pattern of the connectors.

Panels can also be specified to be pre-finished to reduce site painting and these finishes are low in toxicity and VOCs. Cut edges that need to be treated with an exterior grade primer should also be specified to be a low-VOC finish.