What Are Wood Shakes?

What wood shakes are

Wood shakes are one of the oldest ways to roof a house in North America. A block of log is split along its grain into thick, rough pieces.

Today most are cut from western red cedar, and the Cedar Shake and Shingle Bureau, a trade group, sets the grading rules the code points to ^{3 1}.

The names have shifted over time. The National Park Service notes that for most of American history, every wood roof piece was called a shingle, split or sawn. The word shake is newer, and the industry now uses it to separate split products from sawn ones ⁵.

Today the difference is fairly clear. Shakes are split by hand and then resawn, or sawn on both sides with a thick, tapered profile. They have strong grain and a rough look.

Shingles are sawn on one or both faces for a uniform, tailored look ⁴. Because the code redirects both to the same family of rules, this one page covers both.

How a wood roof keeps water out

Like slate, a wood roof works by overlap. Each piece is held by two nails, and the rows above cover those nails ¹.

The part of each piece left showing to the weather is called the exposure.

The code limits exposure by the length and grade of the piece and by the roof slope ¹.

Shakes have rough faces, so they do not lie tight on each other. Wind can push rain and snow through the gaps.

That is why the code asks for an interlayment on shake roofs: a strip of felt meeting ASTM D226 Type I laid between each course ¹.

The bureau's manual says the bottom edge of the felt should sit above the butt of the shake at twice the weather exposure ³.

Shingles are smooth and lie close together, so they get no felt between courses. The bureau is blunt about it: never interlay shingles with felt ³.

Wood also needs air. Pieces are spaced apart, 3/8 to 5/8 inch for shakes and 1/4 to 3/8 inch for shingles in the bureau's manual, so the wood can swell when wet and dry out after rain ³. Learn more about airflow on our roof ventilation page.

Read the stack from the top: water that gets past a shake lands on the felt, and the felt sends it out onto the face of the course below.

Shakes vs shingles: split vs sawn

The bureau names four shake styles and one shingle family. Shapes and terms below come from its manual ³.

The NPS notes that modern shakes are generally thicker than old handsplit shingles and are usually left rough rather than smoothed ⁵.

Sources: [3] [5]

Grades and treatments

The bureau grades its products and offers two pressure treatments ³. The code names the grades it accepts in Tables R905.7.4 and R905.8.5 ¹.

The code accepts Grade 1, 2 or 3 shingles of naturally durable wood. For shakes, it asks for Grade 1 naturally durable, preservative-treated or fire-retardant-treated, and Grade 1 or 2 for tapersawn shakes ¹.

Worked example: how much of each piece may show?

Exposure limits from the 2021 IRC tables for Grade 1 shingles and shakes ¹. The bureau's manual gives the same shingle figures ³.

Less exposure means more pieces per roofing square. So a 3:12 shingle roof uses more wood than the same roof at 6:12. Lower grades get shorter exposures still.

Where wood shakes are used

Wood roofs are common in the Pacific Northwest, where western red cedar grows, and on Cape Cod, cottage, craftsman and lodge-style homes across the country. Shingles are also used on walls, gables and dormers.

The NPS notes that sawn shingles were cheap and easy to get by the late 1800s and went onto roofs, gables and walls alike ⁵.

Wood is used less in wildfire country unless it is fire-retardant treated, and some local codes there limit untreated wood roofs. It is also a careful choice in very wet, shaded places, where moss and rot can take hold. Within 15 miles of salt water, the bureau calls for Type 316 stainless nails ³.

Benefits of wood shakes and shingles

• Natural look. Split grain and color that weathers to silver-grey.
• Light weight. The NPS notes wood was much lighter than tile and needed lighter, cheaper framing ⁶.
• Spaced decks. The code allows solid or spaced sheathing, which lets air reach the back of the wood ¹.
• Repairable. The bureau says single pieces can be repaired, and prompt repairs help the roof last ³.
• Fire-treated options. Certi-Guard products can be used in Class A, B and C roof systems ³.
• Historic match. Custom handsplit shingles are still made the old way with a froe and mallet ⁵.

Limitations of wood shakes

• Fire. Untreated wood carries no fire class on its own. Only treated wood in a tested assembly earns one ².
• Moisture. Wet, shaded roofs grow moss and rot faster.
• Upkeep. Gutters, valleys and the roof surface need regular clearing ³.
• Wide life range. The NPS gives wood roofs anywhere from 15 to over 60 years ⁵.
• Skilled crews. Felt interlay, spacing and exposure all need to be right ³.
• Insurance. Some insurers ask more questions about wood roofs; check before you choose.

What drives the cost of a wood roof

We do not quote prices here. These are the things that move a wood roof quote up or down. Get a rough figure with the roof cost calculator.

• Shake or shingle. Thick shakes use more wood per piece.
• Grade. Premium and Number 1 cost more than Number 2 or 3.
• Treatment. Fire-retardant or preservative pressure treatment adds cost.
• Slope. Low slopes need shorter exposure, so more pieces ¹.
• Deck. Spaced boards, solid sheathing, or a vented system with spacers ³.
• Fasteners. Stainless steel near the coast and with treated wood ³.
• Felt interlay. Labor for laying felt between shake courses.
• Roof shape. Hips, valleys and dormers need cut pieces and flashing.

How a wood shake roof is installed

This is what you should see happen. It is not a do-it-yourself guide. Roof work is a fall risk, and a licensed roofer who installs wood should do it.

1. The crew checks the slope is at least 3:12 ¹.
2. The deck goes on: solid sheathing, or 1×4 boards spaced at the weather exposure ¹. For wood shingles, where January averages 25°F or colder, the ice-barrier area must be solid ¹.
3. Underlayment and an ice barrier go on at the eaves where required.
4. A doubled or tripled starter course is set at the eave ³.
5. Shakes go on with two nails each and a felt strip between courses; shingles go on with two nails and no felt ^{1 3}.
6. Joints in rows next to each other are offset at least 1½ inches, and pieces are spaced for swelling ³.
7. Valley flashing of at least 26-gauge metal goes in, then hip and ridge pieces ¹. See our valley flashing page.

Caring for a wood roof

• Clean gutters and downspouts, usually in spring and fall, as the bureau suggests ³.
• Clear leaves and twigs that keep the roof wet; the bureau says garden-hose pressure can move some debris ³.
• Do not power wash; the bureau says it can be extremely damaging ³.
• Zinc or copper strips at the ridge can help control moss, per the bureau ³.
• Avoid topical sprays that claim fire resistance or promise ten years of protection; the bureau warns against both ³.
• With pressure-treated wood, ask the treatment company before using any stain or cleaner ³.

Warning signs and problems to watch

• Moss, lichen or dark, soft patches that stay wet
• Split, cupped or curled pieces
• Missing pieces after wind
• Rust streaks from the wrong nails
• Leaks at valleys and chimneys
• Rot in the deck boards, seen from the attic

A sign points to a possible cause, not a confirmed one; a roofer on site makes the call.

What the building code says about wood shakes and shingles

These rules come from the 2021 International Residential Code, read as adopted in Maryland. Most states adopt the IRC, sometimes with changes, so your building department's edition is the one that applies.

Sources: [1] [2]

Wood shakes vs other roof coverings

From the same chapter of the 2021 IRC and R902.1 ^{1 2}. Compare looks, upkeep and weight on the roofing materials guide.

Common misconceptions

Myth Shakes and shingles are the same thing.

Reality Shakes are split or thick-sawn and get felt between courses; shingles are sawn smooth and never get felt ³.

Myth A spray-on coating makes wood fire-safe.

Reality Code fire-retardant wood is pressure-impregnated per AWPA C1 ², and the bureau warns against topical sprays that make fire claims ³.

Myth Power washing cleans a cedar roof best.

Reality The bureau says power washing can be extremely damaging ³.

Myth Spaced boards are a sign of a cheap deck.

Reality The code allows spaced sheathing for wood, and it lets air reach the back of the wood ¹.

Myth Any galvanized nail is fine.

Reality The bureau calls for stainless Type 304 or 316 or heavily hot-dipped galvanized nails, and Type 316 near salt water and with treated wood ³.

Local codes and climate

The rules on this page come from the 2021 International Residential Code. States, counties and cities adopt the code on their own schedule and can change it. Wood roofs are where local rules differ most.

Wildfire areas may require a Class A or Class B roof assembly, which untreated wood cannot meet; treated wood can be part of such systems ^{2 3}. Ask your building department which class your address needs.

Climate shapes the details. For wood shingles, where the average January temperature is 25°F or colder, the code requires solid sheathing in the ice-barrier area ¹.

Near the coast, the bureau calls for Type 316 stainless nails within 15 miles of salt water ³.

In humid areas, the bureau prefers a vented system with spacers or nailing strips under the wood ³.

Are wood shakes right for you?

• Wood makes sense if your slope is at least 3:12, your area allows it, and you will keep up with cleaning.
• Pick shakes for a rough, rustic look; pick shingles for a neat, tailored one.
• In wildfire areas, ask for fire-retardant-treated wood with labelled bundles and confirm the assembly's class ².
• Ask for the grade, treatment, nail type, exposure and deck type in writing.
• Compare wood with other coverings using the roof material selector.

Keep going

• Roof replacementWhat a full reroof involves
• Roof repairFixing split, missing and rotted pieces
• Roof inspectionWhat a full roof check covers
• Choosing a rooferQuestions to ask before you hire

Related terms

Roof Ventilation

Roof ventilation is the system of vents that lets outside air enter an attic low, near the eaves, and leave high, near the ridge, so heat and moisture do not build up under the roof deck.

Roof Sheathing

Roof sheathing is the layer of plywood, OSB or wood boards nailed across the rafters or trusses.

Roof Underlayment

Roof underlayment is a sheet laid over the whole roof deck before the shingles or other roof covering go on.

Slate Roofing

Slate roofing is a roof covering made of thin pieces of natural stone, split from quarried slate rock and nailed to a solid roof deck in overlapping rows.

Clay Tile Roofing

Clay tile roofing is a roof covering made of tiles shaped from natural clay and fired in a kiln, laid in overlapping rows over a solid deck and a waterproof underlayment.

Roof Pitch

Roof pitch is the steepness of a roof, written as the inches it rises for every 12 inches it runs horizontally, so a 6/12 roof climbs 6 inches per foot.

Valley Flashing

Valley flashing is the lining installed in a roof valley, the inside corner where two roof slopes meet, so the water both slopes send into that one line runs down to the eave instead of into the deck.

Asphalt Shingles

Asphalt shingles are roofing pieces made from a fiberglass mat coated with asphalt and topped with mineral granules, laid in overlapping rows so water runs off the roof.

Also referenced from: Composite Roofing