Cedar 1x10 Lumber

Cedar 1x10 is a wide board cut from Western Red Cedar, and contractors reach for it when they want a material that fights rot on its own. Western Red Cedar is renowned for its naturally occurring resistance to moisture, decay and insect damage. Its natural durability, dimensional stability and exceptional beauty make it ideal for a wide variety of exterior and interior uses. That matters in a climate that cycles wet and dry, freezes and thaws, all season long.

Here’s the thing most buyers get wrong: they order “cedar 1x10” and assume the grade, surface, and profile sort themselves out. They don’t. Grade decides whether the finished wall reads upscale or rustic. Surface texture decides how it takes a stain. And the profile — square edge, bevel, shiplap, T&G — has to match the application or the order’s a waste. Get those three right and cedar earns its keep.

What It Is and Where It Goes

Western Red Cedar is the workhorse here, not the aromatic closet-lining stuff. Western Red Cedar (Thuja Plicata in Latin) combines form and function like no other wood species or man-made material. It’s also easy to handle on the jobsite. It is lightweight and easy to handle and install for both the professional and do-it-yourselfer.

The other reason crews like it: cedar takes finish without a fight. Western red cedar is pitch and resin-free. Which means it’s ideal for accepting and holding a wide range of beautiful finishes including elegant dark stains, shabby chic bleaches, traditional solid colors and naturally beautiful semi-transparents.

Where does a 1x10 end up? Plenty of places. Typical uses include interior and exterior window trim, interior and exterior door trim, baseboards, soffit and fascia, frieze boards, and closet shelving. Outdoors, it’s a go-to for the visible work. Western Red Cedar is a top choice for outdoor projects like siding, decking, and ceilings. This durable wood is naturally resistant to rot, decay, and insect attacks, ensuring anything you build with it will stand the test of time.

Nominal vs. Actual Size, and What S1S2E Means

A 1x10 isn’t ten inches of anything. The “1x10” is a nominal label. The nominal size is 1x10. The actual finished size is 1” x 9 1/4”, with a tolerance of ±1/16”. Lengths are typically available in 4’, 8’, 10’, 12’, 16’, or 20’. Some boards run a hair thicker — actual size 9 1/4” wide by 7/8” thick shows up depending on the mill.

The surface code tells you how the board’s been dressed. An S1S2E (Surfaced One Side, Two Edges) finish offers a dimensional solution for trim, fascia, and cladding applications. The face side is smoothly planed, while the reverse side retains a natural texture. Both edges are square and surfaced for clean, uniform installation. That one-smooth, one-rough setup is a feature, not a flaw — a reversible board, one side smooth, one side rough lets you pick your texture at install.

Profile changes the face width you actually see once it’s on the wall. Here’s how the common 1x10 profiles compare:

Profile	1x10 Face Width	Notes
Square edge (standard)	9 1/4”	Trim, fascia, beam wrapping, shelving
Tongue & Groove	8 5/8”	Requires a 3/8” tongue on 1x10
Shiplap	8 1/2”	Accent walls, ceilings, cladding

That T&G detail trips people up. 1x8, 1x10, and 1x12 T&G profiles require a 3/8” tongue, instead of a 1/4” tongue. Order accordingly.

Grades, Profiles, and Picking the Right One

Grade is the single biggest decision you’ll make, and it’s purely about appearance and how the wood holds a line.

The premium end is clear stock. Clear Vertical Grain Heart is the highest bevel siding grade. It is sawn vertical grain (edge grain) and is kiln-dried. Pieces have a smooth face of decay resistant heartwood and are free from growth characteristics that affect appearance or performance. Pieces have excellent dimensional stability and hold finishes exceptionally well. That’s the choice for refined, upmarket work where knots don’t belong.

Most jobs, though, run knotty — and for good reason. WRC is sold in different grades, with “appearance” or “appearance knotty” being the most popular. Select Tight Knot brings the character without falling apart. Knotty siding has warmth and casual charm and is ideal for homes, cottages, club-houses and applications where a rustic appearance is desired. The way grades stack up:

• Clear Grade — premium quality with minimal knots, perfect for high-end projects where a flawless appearance is essential.
• Select (STK) — high-quality boards with small, tight knots that add natural character without compromising strength.
• Knotty Grade — more economical with larger, more prominent knots, ideal for rustic or casual designs.

There’s a fourth option worth knowing if you’re chasing long, dead-straight runs of fascia or trim: engineered cedar. Manufactured using finger-jointed and laminated Western Red Cedar, this engineered board provides enhanced stability, reduced warping, and long lengths that maintain consistent appearance and performance. It’s ideal for vertical or horizontal applications where natural beauty and straight lines are essential — fascia, frieze boards, rake trim, wrapped columns.

Match the profile to the job. Square-edge boards handle trim, fascia, and shelving. For siding, bevel is the standard. Western Red Cedar bevel siding is the most widely used cedar siding type. Bevel siding is installed horizontally and gives an attractive shadow line which varies with the thickness of siding selected. The designer may choose from plain bevel, rabbetted bevel, or wavy edge bevel. Shiplap and T&G are your accent-wall and ceiling profiles. Western Building Center carries the standard S1S2E square-edge cedar 1x10 in 8, 10, 12, and 16-foot lengths.

Installation: Stability Starts Before the First Nail

Cedar moves with moisture. Always has, always will. The work you do before installation decides how much it moves after.

Start with the right material. Kiln dried for stability beats green cedar every time when dimensional stability matters. Then let it adjust to your site. For proper installation of decking, allow lumber to acclimate on site 1-2 weeks prior to installation.

The real key is moisture content matched to the local climate — which, in Montana’s dry interior, is a different target than a coastal install. Wood will shrink and swell with any changes in moisture content and weather. According to WRCLA, to minimize dimensional change after installation, install bevel siding at a moisture content that matches with local climate as closely as possible. If climate in a particular region causes wood to maintain 8% to 13% moisture content annually, then the most ideal siding would be installed at a moisture content within that range, and the material would be stored, stickered and protected for a week to ten days prior to application.

How you store it before install matters just as much, especially through a Montana winter. It is best to store the siding flat and off the ground with a vapor barrier so that moisture is not absorbed through the bottom boards of the stack. If stored outside, the siding should be protected with a waterproof covering elevated in the center so that water does not pool on the cover. Do not completely seal the bundle, as good air circulation is required to prevent any blue stain or molding.

Finishing isn’t optional on exterior cedar, and the ends count too. As with every unfinished exterior wood, applying a quality finish to all surfaces (including the ends) is recommended. An exterior finish protects the wood from moisture absorption and UV degradation, and helps prevent staining caused by mold and mildew. Plan to keep at it: most exterior finishes do have to be re-coated or reapplied every 3-5 years depending on the UV exposure to your home. One more field note — watch for mill glaze. On occasion, the siding may have a mill glaze that is produced when the material is manufactured through the planer. When mill glaze occurs, it is recommended to remove it by pressure washing the wood or sanding prior to staining.

Frequently Asked Questions

What are the actual dimensions of a cedar 1x10? Despite the name, it’s not a full inch by ten inches. The nominal size is 1x10. The actual finished size is 1” x 9 1/4”, with a tolerance of ±1/16”. Some mills run the thickness slightly heavier at 7/8”.

What does S1S2E mean? It’s a surfacing code. S1S2E means Surfaced One Side, Two Edges. The face side is smoothly planed, while the reverse side retains a natural texture, and both edges are square and surfaced for clean, uniform installation. In practice the board is reversible — smooth on one side, rough-sawn on the other.

Clear or knotty cedar — which should I buy? Depends on the look. Clear siding gives premium quality appearance and is ideal for prestigious, upmarket applications. Knotty siding has warmth and casual charm and is ideal for homes, cottages, club-houses and applications where a rustic appearance is desired. Select Tight Knot is the most popular middle ground.

Why does cedar resist rot when other softwoods don’t? It’s built into the wood. Western Red Cedar overcomes the negative aspects of most wood products due to its weather-resistant qualities and naturally occurring preservatives that resist insects and decay.

Do I need to acclimate cedar before installing it? Yes. Allow lumber to acclimate on site 1-2 weeks prior to installation. The goal is to get the board’s moisture content in line with your local climate before it goes up, so it doesn’t shrink or swell on the wall later.

How often does exterior cedar need refinishing? Most exterior finishes have to be re-coated or reapplied every 3-5 years depending on the UV exposure to your home. Finish all surfaces, ends included, the first time around.

Can I get cedar 1x10 in a tongue-and-groove or shiplap edge? Yes — the same nominal board mills into different profiles. Note the face width changes: square edge 1x10 runs a 9 1/4” face, T&G runs an 8 5/8” face, and shiplap runs an 8 1/2” face. And the 1x10 T&G profile requires a 3/8” tongue.