Architects are fortunate to have a wide variety of exterior wall finish (a.k.a. cladding) materials available to them, and our selection of which to use is informed by myriad factors including project budget, the material’s durability, the climate zone we are working in, and the aesthetic effect we wish to achieve. Among the wide variety of materials available to us are cement plaster, fiber cement board, vinyl, and aluminum siding, and last but not least, wood siding.
Wood siding offers the authenticity inherent in a natural product and the opportunity to express that authenticity in the expression of the wood’s grain when revealed in the sun. In our northern California coastal environment, redwood and cedar siding are the two de rigueur choices for exterior wood cladding. This article will discuss the qualities and specifications involved to make informed decisions as to species, grade, style and finish options available when exterior cedar siding is the material of choice.
Use Only Certified Cedar
Certified wood products come from responsibly managed forests. With third-party certification, an independent organization develops standards of good forest management, and independent auditors issue certificates to forest operations that comply with those standards. Basic requirements or characteristics of forest certification programs include protection of biodiversity, species at risk and wildlife habitat; sustainable harvest levels, and third-party certification audits performed by accredited certification bodies. In the U.S., the Forest Stewardship Council (FSC) is the generally recognized forest certification program for cedar building materials.
Both red and white cedar are used for siding materials, but there are differences between the two species. Red cedar siding is usually more durable and comes in a variety of styles, lending itself to more design options. White cedar siding only comes in one style, so its design possibilities are limited. White cedar weathers to an attractive silver-gray shade, and because of its light color and weathered look, white cedar is quite often specified in coastal areas. White cedar siding can also be bleached, thus immediately taking on the silvery color that normally develops over years of weathering in the sun. When a saturated color is preferred, both red and white cedar siding can be stained in a variety of shades.
Red and white cedar siding are available in different grades, the choice of which has a strong impact on the exterior aesthetic. Clear grades – usually designated as A or B – have a fine, smooth appearance that shows very few imperfections and growth characteristics. These grades tend to hold finishes better and give the exterior a more modern look. Knotty grades demonstrate knots and other growth characteristics that give the siding a rough, textured surface. This type of siding is ideal when a more rustic appearance is preferred.
There is only one style available when working with white cedar siding – shingles. Shingles are small, individual pieces of siding that are hung on the exterior in an overlapping fashion to cover the entire surface. They offer a more tailored look and work well on cottage-style homes. Red cedar siding is not only available as shingles and shakes, but in a variety of clapboard options as well including bevel, tongue-and-groove, and board-and-batten siding. Bevel siding is hung horizontally and is cut so it’s thicker at one end to give it an attractive rustic look. Tongue-and-groove cedar siding is one of the more versatile styles because it can be installed horizontally, vertically and diagonally. Board-and-batten siding is installed vertically, and the boards are available in a wide variety of widths the choice of which sets the “cadence” in the spacing of the battens.
Cedar siding typically has two finishing options, semi-transparent or solid finish. A semi-transparent finish is applied in a single coat and protects the siding from the elements. However, because the finish is semi-transparent, it allows the natural color and texture of the cedar to show through. Similarly, a solid finishes also protects the siding from the elements, but stains the cedar to alter its natural color. Even though it alters the cedar’s color, a solid finish does exhibit the wood’s original texture. Because it is a two-coat application, solid-finish siding doesn’t have to be refinished as often as siding with a semi-transparent finish. The finish should ideally be matched to the grade of cedar siding selected, with semi-transparent finish working best with a clear-grade siding, and a solid finish the better choice for knotty-grade cedar.