Cedar 1x4 Lumber

A 1x4 cedar board is not one inch by four inches. A 1x4 board measures 3/4 inch thick by 3-1/2 inches wide. That’s the first thing to get straight, because every project plan built on the label instead of the real number comes up short.

Here’s the honest framing: this is a light-duty trim board, not a structural member. Cedar earns its keep because it’s naturally resistant to rotting, decay and insect infestations. That matters for exterior trim, fencing, and garden beds exposed to Montana moisture and freeze-thaw cycling. But a 1x4 won’t carry load. So the real decision isn’t strength — it’s matching the grade to how visible the finished surface will be, then handling the board right so it stays flat after install.

Sizing and the Grades That Actually Matter

The name is historical. The “1x4” is a nominal name from when lumber was sold rough-sawn. Drying and planing cut it down. Two things shrink it between the mill and your hands: drying removes moisture and causes the wood to contract, and planing removes surface roughness to reach a consistent finish. A board labeled 1x4 loses about 1/4 inch in thickness and 1/2 inch in width from rough nominal to finished actual.

The practical cost is real. Design a five-shelf bookcase with 4-inch shelves, buy 1x4 boards, and each shelf comes in 1/2 inch narrower than you planned. Your design doesn’t fit. Always use actual dimensions when you build — 3/4” thick, 3-1/2” wide.

For budgeting, a 1x4 yields 2.67 board feet per 8-ft board. The math is simple: board feet equals length in feet times width in inches times thickness in inches, divided by 12.

Nominal	Actual	Board Feet (8 ft)
1x4	3/4” × 3-1/2”	2.67

Now the part that trips people up: grade. Grade affects how a board looks, not how big it is. A Clear 1x4 and a #2 1x4 are both 3/4” × 3-1/2”. Don’t overpay for Clear on something that gets painted, and don’t put #2 knots on a stained showpiece.

Grade	Knots	Best For
Clear	Minimal to none	Visible, stained, high-end work
Select / Prime	Tight, minimal	Visible trim, interior shelving
#1 Common	Sound knots, splits	Fences, semi-visible work
#2 Common	Larger knots, checks	Painted or hidden work

There’s a middle ground worth knowing. D-Select Western Red Cedar features sound tight knots and a clean, usable face — an appearance grade with great visual appeal, ideal for siding, soffits, trim, and paneling where a natural look is desired without going all the way to clear grades.

You’ll also see surface designations. S1S2E means Surfaced One Side, Two Edges — the face side is smoothly planed while the reverse retains a natural texture, and both edges are square and surfaced for clean installation. If stability matters on long runs, engineered finger-jointed cedar is manufactured using finger-jointed and laminated Western Red Cedar, providing enhanced stability, reduced warping, and long lengths that maintain consistent appearance. Western Building Center carries 1x4 cedar in S1S2E in 10-foot, 12-foot, and 16-foot lengths.

Choosing Cedar, and Working It Without Splitting It

First, know which cedar you want. Aromatic cedar — the white and red variegated board with a pleasant fragrance — is used as closet lining and in furniture that holds clothing. This is a product of Eastern cedar trees. Western Red Cedar is the construction-grade choice: it’s used more extensively in the construction industry and does not have the strong odor associated with its eastern cousin.

Where does 1x4 cedar go? Naturally rot-resistant, it’s used for outdoor trim, siding, raised beds, and fence work. Indoors and on protected exteriors, it works for interior and exterior window and door trim, baseboards, soffit and fascia, frieze boards, and closet shelving. What it doesn’t do is structural duty — treat it as a cosmetic or light-duty board.

The trade-off against spruce-pine-fir is straightforward. Cedar takes stain well but doesn’t hold screws as firmly as denser species. You’re paying for rot resistance and looks, so put it where moisture and visibility justify it. On the finishing side, cedar rewards you: Western Red Cedar is pitch and resin-free, which means it’s ideal for accepting and holding a wide range of finishes including dark stains, bleaches, solid colors and semi-transparents.

Handling is where Montana builders win or lose. Cedar’s soft and splits — so drill pilot holes near board ends, every time. Moisture content is the other half. Mills plane cedar to standard actual dimensions after kiln-drying to 8-12% moisture content — ideal for indoor or covered outdoor use. Look for the right stamp: “S-GRN” means green, over 19%; “S-DRY” means air-dried to 19% max. Target KD19, kiln-dried, for stability. And don’t push your luck on wet stock — aim for 7-12% indoors and avoid over 15% to prevent cupping.

For anything going outside, let it settle before you fasten it down. Allow lumber to acclimate on site 1-2 weeks prior to installation. In a dry, swingy climate that gap between delivery and install is what keeps your trim from opening up later.

Two more practical notes. Order extra — 8-foot boards can run 96-1/4 inches, so order 10% extra, and add 15% for cuts and sanding. And wear a mask: cedar dust irritates lungs.

Frequently Asked Questions

What are the actual dimensions of a 1x4 cedar board? A 1x4 board measures 3/4 inch thick by 3-1/2 inches wide, not one inch by four inches. Always design with the actual numbers.

Which grade should I buy? Match grade to visibility. Most big-box lumber is #2 — fine for framing, rough shelving, and anything painted or hidden. If the board will be visible, look for Select or #1 Prime. For stained work where grain matters, you want Clear or better.

Is cedar strong enough for framing? Treat a 1x4 as a trim and light-duty board. While cedar has the strength to be used structurally in larger dimensions, a 1x4 belongs in non-load-bearing roles — trim, fencing, shelving, and decorative work.

What’s the difference between Western Red Cedar and aromatic cedar? Western Red Cedar suits outdoor decks and siding; Aromatic Red Cedar is for closets and chests. The aromatic type carries the fragrance used in clothing storage, while Western Red is the workhorse for construction and outdoor trim.

How do I keep cedar from splitting when I fasten it? Drill pilot holes — cedar splits easily, especially near board ends. Keep in mind it doesn’t hold screws as firmly as denser species, so plan your fasteners accordingly.

What moisture content should I look for? Target KD19, kiln-dried, for stability — aim for 7-12% indoors and avoid over 15% to prevent cupping. Check the end stamp before you buy.

How much extra should I order? Plan for waste. Order 10% extra for length tolerances and another 15% for cuts and sanding. Cutting it close on cedar usually means a second trip.