Wood Shake and Shingle Roofing

Wood shake and shingle roofing represents one of the oldest and most visually distinct categories of residential roofing material used across the United States. This page covers the structural and material differences between shakes and shingles, how each type performs over its service life, the scenarios where wood roofing is most commonly specified or replaced, and the regulatory and decision factors that govern material selection. Understanding these distinctions is essential for property owners, inspectors, and contractors navigating fire ratings, permitting requirements, and climate considerations.

Definition and scope

Wood shake and shingle roofing encompasses roof coverings cut or split from natural wood — most commonly western red cedar, though eastern white cedar, pine, and redwood are also used in regional markets. The two products are structurally distinct:

• Wood shingles are sawn on both faces, producing a smooth, uniform taper from thick butt to thin tip. Thickness at the butt typically runs 0.40 inches for a No. 1 grade shingle.
• Wood shakes are split on at least one face, producing a rougher, more textured surface with greater thickness variation. Hand-split and resawn shakes carry a butt thickness of 0.75 inches minimum under grading standards published by the Cedar Shake and Shingle Bureau (CSSB).

The CSSB publishes grading rules recognized by the International Building Code (IBC) and International Residential Code (IRC). Under these rules, No. 1 ("Blue Label") shingles and No. 1 ("Certi-Split") shakes are composed of 100% clear, edge-grain heartwood — the grade required for most exposed roofing applications. No. 2 and No. 3 grades permit flat grain and limited sapwood, reducing both cost and weather resistance.

From a broader roofing materials comparison standpoint, wood products occupy a distinct niche: higher aesthetic value than asphalt shingles, lower weight than concrete tile, but greater maintenance demand than metal or synthetic alternatives.

How it works

Wood shake and shingle roofing functions through a drainage-and-drying cycle rather than a waterproof membrane. Each course overlaps the course below by a specific exposure distance — typically 5 inches for 16-inch shingles and up to 10 inches for 24-inch shakes on slopes of 4:12 or greater. Water sheds from course to course before reaching the deck. This system depends on three conditions:

1. Adequate roof slope — The IRC (Section R905.7) requires a minimum 3:12 pitch for wood shingles and 4:12 for wood shakes. Below these thresholds, the drainage cycle fails and moisture infiltration accelerates.
2. Air circulation beneath the material — Shakes and shingles require a ventilated airspace above the deck or a skip-sheathing substrate (spaced boards rather than solid OSB or plywood) to allow drying from below. Without this, fungal decay begins within the wood cells.
3. Appropriate underlayment — The IRC specifies No. 30 asphalt-saturated felt as interlayment between shake courses. Roof underlayment selection affects both moisture management and fire classification.

The natural tannins in western red cedar provide inherent resistance to insects and fungal decay, but this resistance diminishes as the heartwood weathers. Untreated cedar shingles typically exhibit a service life of 20 to 30 years under routine maintenance; pressure-impregnated fire-retardant treated (FRTW) products carry shorter manufacturer-certified life spans, often 15 to 25 years, because the treatment chemistry can accelerate some forms of surface degradation.

Common scenarios

Wood shake and shingle roofing appears most frequently in four distinct scenarios:

New construction in low-fire-risk zones. Architects specify No. 1 cedar shakes for aesthetic continuity with craftsman, Tudor revival, and Pacific Northwest vernacular styles. Jurisdictions outside California's designated Wildland-Urban Interface (WUI) zones retain broader latitude for untreated wood roofing.

Re-roofing in historic districts. Preservation standards under the Secretary of the Interior's Standards for Rehabilitation — administered by the National Park Service — often require material-in-kind replacement. A property listed on the National Register of Historic Places may face restrictions that prohibit substituting synthetic shake or asphalt shingles.

Replacement driven by moss and decay. Moss, algae, and biological staining accelerate moisture retention in wood roofing faster than in most competing materials. Moss root systems physically displace shingle courses, causing lifting and cracking. Remediation typically requires chemical treatment with zinc or copper strips, but heavily colonized roofs exceeding 40% surface coverage are generally candidates for full replacement.

Fire-retardant upgrade projects. Property owners in California, Oregon, and Washington face increasing pressure from state fire codes and insurance carriers to upgrade wood roofing to Class A fire-rated assemblies. California Building Code Section 1505 prohibits new installation of unrated wood roofing in High and Very High Fire Hazard Severity Zones (FHSZ) designated by the California Department of Forestry and Fire Protection (CAL FIRE).

Decision boundaries

Selecting, retaining, or replacing wood shake and shingle roofing involves several hard constraints and comparison thresholds:

Fire rating requirements are the primary hard constraint. The IBC classifies roof assemblies as Class A, B, or C under ASTM E108 and UL 790 test standards. Untreated wood shingles and shakes achieve only Class C ratings as individual materials. Achieving Class A requires a listed assembly that incorporates fire-retardant treatment, specific underlayment layers, or a combination with a non-combustible substrate. For properties where Class A is mandatory by local code or insurer requirement, untreated wood roofing is not a viable option regardless of aesthetic preference — see the fire ratings for roofing materials reference for full classification detail.

Slope boundaries create a second hard limit. Below 3:12 pitch, wood shingles are code-prohibited; below 4:12, wood shakes are prohibited under the IRC. Neither material is appropriate for flat or low-slope roofing systems.

Maintenance capacity functions as a practical decision boundary. Wood roofing requires inspection every 3 to 5 years, periodic cleaning, and individual shingle or shake replacement as units crack or cup. Properties without regular maintenance programs — common in rental housing or estates with absentee ownership — accumulate decay faster than the material's rated service life suggests.

Cost comparison with alternatives affects long-term value calculations. No. 1 cedar shake installation typically costs 40% to 80% more per square (100 sq ft) than standard 3-tab asphalt shingles, according to cost data published by RSMeans, while offering a comparable or shorter service life depending on climate. Synthetic roofing materials engineered to replicate shake appearance have closed much of this performance gap at lower maintenance cost, making them a frequent substitute in jurisdictions where fire ratings or HOA aesthetics standards constrain material choice.

The broader roofing resource index provides context for how wood shake and shingle systems fit within the full spectrum of residential and light commercial roof types, including comparisons with slate roofing and tile roofing for property owners evaluating premium natural materials.