Synthetic Sidewall Shingles: A Builder’s Guide to Polymer Siding Materials and Installation

Homeowners and builders today have more exterior cladding options than ever before. While natural wood siding remains a classic choice, modern polymer materials have matured into a compelling alternative that combines the look of traditional cedar shingles with significantly less maintenance. For those weighing material options for a new build or re-siding project, understanding what synthetic sidewall shingles offer is essential to making an informed decision. Products like CertainTeed’s Sawmill Shingles illustrate how far polymer siding technology has come, offering realistic wood texture without the ongoing upkeep that cedar demands. Before committing to a material, it helps to compare synthetic options against other modern siding materials to see where polymer shingles fit into the broader landscape.

What Are Synthetic Sidewall Shingles

Synthetic sidewall shingles are injection-molded polymer panels designed to replicate the appearance of natural cedar shingles. Unlike vinyl siding, which typically comes in long horizontal panels, synthetic shingles are individual units that mimic the staggered, textured look of hand-laid wood. CertainTeed’s Sawmill Shingles, one of the leading products in this category, are produced from a durable polymer compound and measure 12 inches in length. They come in seven widths ranging from 4 inches to 8 inches, which allows for the randomized exposure pattern that makes the installation read as authentic shingle work.

Material Composition and Manufacturing

The polymer compound used in synthetic shingles is formulated for impact resistance, UV stability, and dimensional consistency. Injection molding allows manufacturers to embed surface details that would be difficult to achieve with wood – including replicated saw marks, subtle grain textures, and precise bevels on the butt ends. This level of detail is what sets premium synthetic shingles apart from basic vinyl alternatives.

Available Colors and Finishes

Synthetic shingles are available in a broad palette of colors. The Sawmill Shingles line alone offers 24 color options, spanning both wood tones and solid colors. The solid colors tend to look most convincing up close, as they avoid the repeating grain patterns that can give away a printed finish. The wood-tone options, while still attractive, benefit from being viewed at typical sight distances on an exterior wall.

Comparing Synthetic Shingles to Natural Alternatives

Choosing between synthetic and natural wood shingles involves trade-offs across several dimensions. The table below summarizes the key differences to help builders and homeowners evaluate which option best suits their project.

The cost premium for synthetic shingles is offset by the near-elimination of long-term maintenance. Builders working with clients who prioritize low upkeep often find that the upfront investment pays for itself within the first decade when factoring in avoided staining labor and material costs. Those considering natural wood should review best practices for installing cedar shingles on exterior walls to understand the maintenance commitment involved.

Installation Methods and Techniques

Installing synthetic sidewall shingles follows many of the same principles as working with cedar, with a few important distinctions that stem from the hollow-backed design of the polymer units. Understanding these differences up front prevents costly rework and ensures a clean, weathertight result.

Cutting and Fastening

Synthetic shingles can be cut with either a utility knife or a circular saw. For straight cuts across the exposure face, a sharp utility knife scored and snapped produces a clean edge with no dust. For angled cuts at corners or around penetrations, a carbide-tipped blade in a miter saw or circular saw delivers precision without melting or chattering the polymer. Fastening is straightforward: standard roofing nails or staples driven through the face at the proper nailing zone hold each shingle in place. The nailing pattern mirrors cedar installation, with two fasteners per shingle placed just above the exposure line.

Corner Details

Because synthetic shingles are hollow-backed, they must butt against corner boards rather than being woven at inside or outside corners. This is a meaningful departure from cedar shingle installation, where skilled installers can weave courses to create seamless corners. CertainTeed addresses this limitation by offering preformed corner shingles that create a clean mitered appearance at outside corners. Inside corners are handled with standard corner boards, against which the shingle ends are trimmed flush.

The standard exposure for synthetic sidewall shingles is 5 inches, which means each 12-inch shingle reveals 5 inches of face while the remaining 7 inches is covered by the course above. Planning the layout requires determining the wall height and calculating course spacing so that full courses land at the top of the wall without a narrow cut course. A clapboard gauge or story pole is invaluable for marking exposure lines across the wall surface before installation begins. Builders who work regularly with siding will find useful techniques in the guide on using a clapboard gauge for accurate siding exposure.