Cedar 1x6 Lumber

A 1x6 cedar board isn’t an inch by six inches. It measures 3/4 inch thick by 5-1/2 inches wide — not 1 inch by 6 inches. That gap isn’t a defect or a scam. It’s the result of drying and planing at the mill, and it’s been standard in the lumber industry for decades. Design to the label instead of the real number and your spacing math comes up short — fast.

Here’s the short version. Cedar is the outdoor wood. Natural oils in the wood resist rot, insects, and moisture. That’s why it shows up on fences, siding, fascia, and deck trim across western Montana — places where freeze-thaw and weather chew up lesser boards. The premium over pine is real, so the trick is matching grade, profile, and finish to the job.

Sizes, Species, and Grades

Thickness stays put across the whole 1x family. Thickness is always 3/4 inch for standard 1x boards. Width loses 1/2 inch on boards up to 6 inches, and 3/4 inch on wider boards. So a nominal 1x6 lands at 3/4” x 5-1/2” every time.

Need true 1-inch stock? Don’t fight the 1x. If you genuinely need 1-inch-thick stock, buy 5/4 lumber (nominal five-quarter, actual ~1-1/8 inch) and surface it down to 1 inch with a planer.

Cedar 1x6 runs in standard lengths. Western Building Center carries it in 10, 12, and 16-foot lengths, all in an S1S2E surface. More broadly, 1x6 boards are available in various standard lengths, typically ranging from 6, 8, 10, 12, 14, and 16 feet.

Spec	Cedar 1x6
Nominal	1” x 6”
Actual	3/4” x 5-1/2”
Standard lengths	6, 8, 10, 12, 14, 16 ft
Step up for true 1”	5/4 stock (~1-1/8”)
Kiln-dried moisture	6–8%

On species: there are two cedars people mean, and they aren’t interchangeable. The white-and-red variegated board with a pleasant fragrance — used as closet lining and in furniture that holds clothing — is aromatic cedar, a product of Eastern cedar trees. That’s the closet stuff. For construction, you want Western Red. Western Red Cedar is used more extensively in the construction industry and doesn’t have the strong odor of its eastern cousin. The trees grow larger in both girth and height and live longer, so a better selection of dimensional lumber is available. WRC is sold in different grades, with “appearance” or “appearance knotty” being the most popular.

Grade drives both looks and cost. Grades run from Select (minimal defects, clear grain) to #2 Common (budget, for painted or utility work). Spelled out: #1 Common has few knots and straight grain, ideal for visible areas; #2 Common has more knots and variations; Select Grade is high-quality with minimal defects for premium finishes; Clear Grade is virtually knot-free.

For exterior work where a few sound knots don’t bother you, the tight-knot grades earn their keep. NPS Tight Knot ensures knots stay sound and secure, and Standard and Better (Std & Btr) grade provides quality assurance. Tongue-and-groove cedar shows up in grade tiers too — Standard (STK) for durable outdoor use with better consistency and fewer imperfections, plus Premium and Premium III Sauna Grade options for higher aesthetics.

Surface Finishes, Profiles, and Where Cedar Earns Its Premium

The same nominal board comes milled several ways. Match the surface to the install.

S3S means three sides cleaned up. S3S (Surfaced 3 Sides) provides a smooth finish, perfect for staining or painting. S1S2E leaves one face rough — what Western Building Center stocks. S1S2E is smooth on 1 side and 2 edges, rough on 1 side. Good when one face shows and the back hides.

For ceilings, soffits, and siding, tongue-and-groove locks tight. The interlocking T&G profile creates a tight, seamless fit that resists warping and movement — ideal for decks, porches, saunas, and feature ceilings. A common profile is the 60° V-Joint, which can be used for ceiling, soffits, siding, or cladding.

Siding has its own profiles worth knowing. Bevel siding — also known as clapboard and lap siding — is thick on the bottom edge, roughly ¾” to 1”, tapering to about ⅛” to ¼” at the top. Channel rustic is lap siding with a 2” channel at the top, a shiplap product rather than T&G. Rabbeted bevel is an upgrade to standard bevel with a shiplap bottom for a more pronounced profile.

Why cedar over pine when it costs more? Durability outdoors, plain and simple. Cedar lasts 10+ years outdoors versus 2–3 years for untreated pine. Outdoors, skip regular pine — it has no natural rot resistance and will fail in two to three years without paint or sealer. The cost gap is real: cedar costs two to three times more than pine. Where that premium pays: outdoor furniture, planters, and anything exposed to weather. Where it doesn’t: painted interior work, where poplar is harder than pine, machines cleaner, and takes paint better than almost any other domestic wood.

Cedar’s application list is long. It’s found in both interior and exterior applications — and homes built with cedar typically use cedar throughout. Typical uses include interior and exterior window and door trim, baseboards, soffit and fascia, frieze boards, and closet shelving. Outdoors, it handles siding, decking, and ceilings.

Installation and Finishing

Cedar resists rot, but install it wrong and it’ll still fail early. Three things matter.

First, let it settle before you fasten anything. For proper installation, allow lumber to acclimate on site 1–2 weeks prior to installation. That window matters more in a dry Montana climate, where boards that go up green will shrink in the wall. Kiln-dried stock helps — kiln-dried boards have a moisture content between 6% and 8%, providing better dimensional stability and less shrinkage or warping.

Second, fasteners. Cedar’s natural acids eat cheap steel. For pressure-treated and exterior work, use stainless steel or coated fasteners. And pre-drill near ends — cedar’s a softwood but it’ll still split on you.

Third, finish — or don’t, knowing what happens. Left unfinished, cedar weathers to gray. Sealed annually with a penetrating oil or spar varnish, it holds its warm reddish color for years. That silver-gray patina is fine if it’s the look you want. If you want the warm tone through Montana winters and high-elevation UV, plan on re-coating. Cedar takes finish well because it’s pitch and resin-free, ideal for holding dark stains, bleaches, solid colors, and semi-transparents.

One last habit worth keeping at the yard: inspect every board before you load it — straightness, knots, and moisture content all matter more than brand or store.

Frequently Asked Questions

What are the actual dimensions of a cedar 1x6? A nominal 1x6 measures 3/4 inch thick by 5-1/2 inches wide. This discrepancy results from industry milling standards, where the rough-sawn board is trimmed and smoothed for uniformity, reducing both thickness and width. Every time 1x6 lumber is used, account for the actual size to ensure accurate fitting and measurements.

Western Red or aromatic cedar — which one for siding and trim? Western Red. It’s used more extensively in the construction industry, doesn’t carry the strong odor of Eastern aromatic cedar, and the larger trees yield a better selection of dimensional lumber. Aromatic Eastern cedar is the closet-lining wood.

Is cedar worth paying 2–3x more than pine? Outdoors, yes. Cedar lasts 10+ years outdoors versus 2–3 years for untreated pine. For painted interior trim and cabinetry, the math flips — poplar’s fine, even grain takes paint uniformly, making it the better choice for any project where clean paint adhesion matters.

What’s the difference between S3S and S1S2E? S3S is surfaced 3 sides — a smooth finish ready for staining or painting. S1S2E is smooth on 1 side and 2 edges, rough on 1 side — a good fit when only one face will be seen.

Do I need to seal cedar, or can I let it gray out? Both work. Left unfinished, cedar weathers to gray. Sealed periodically with a penetrating oil or spar varnish, it holds its warm reddish color for years. Sealing is the move if you want to keep the color through hard sun and winters.

How long should cedar acclimate before installation? Allow the lumber to acclimate on site 1–2 weeks prior to installation. Combined with kiln-dried stock at 6% to 8% moisture content, that limits shrinkage and warping once it’s up.

What fasteners should I use with cedar? Stainless steel or coated fasteners — cedar’s natural acids corrode untreated steel, leaving streaks and weakening the connection. Pre-drill near board ends to keep from splitting.