Cedar 4x4 Posts

Cedar 4x4 posts are for fences, railings, pergolas and gazebos where you want the wood to show. Cedar’s natural resistance to rot and decay is a good reason to buy it for exposed outdoor work. Get the length, surface and actual size right, and you have the post your project needs without buying extra wood just to cut it off.

4x4 Red Cedar Posts for Outdoor Work

Buy 4x4 red cedar posts for visible exterior work where decay resistance matters. A fence line or exposed railing puts the wood out in the weather, and that natural resistance is a useful property there.

In Montana, spring fence repairs often start while snowmelt is keeping the ground wet for weeks. Choose a post suitable for direct burial for a buried-post job; natural decay resistance and ground-contact suitability are separate buying decisions. For railings and roofed structures, establish post capacity, connections and local snow and wind requirements as part of the design. Appearance and length are separate from load capacity.

Cedar Posts Surfaced on Four Sides: 10 Feet or 8 Feet

The two WBC items to compare are the 10-foot cedar appearance post surfaced on four sides and the 8-foot cedar appearance post surfaced on four sides. S4S means surfaced on four sides. That planed surface is the reason to choose these posts for exposed work where you want a smooth look.

Cedar appearance post	Length	Surface
10-foot post	10 feet	Surfaced on four sides
8-foot post	8 feet	Surfaced on four sides

Buy the 10-foot post for longer post cuts. It gives you 2 feet more material than the 8-foot post. Buy the 8-foot post for shorter cuts that fit that length; extra length has no value once it lands in the scrap pile.

When you compare 4x4 cedar posts for sale, compare the finished cuts you need, not just the height you want to see above the ground. Allow for the full post length required by your connection or burial design before choosing between the two.

Cedar Lumber 4x4: Is It Really Four Inches Square?

A smooth cedar 4x4 can measure 3½ inches by 3½ inches. That is the finished cross section of the S4S examples, so four inches square is the wrong measurement to assume for hardware or an existing opening.

Match your hardware and joinery to the actual post you choose. This matters on a railing repair, where a replacement has to meet existing rails and trim. Treat rough posts the same way: a rough surface is not a dependable measurement.

Smooth Red Cedar Lumber: Surface and Grade Are Different

Choose smooth red cedar lumber for the clean, planed look of exposed fence and railing posts. Smooth describes the surface. It does not mean clear wood: smooth cedar can still have knots and some wane, the missing wood along an edge.

Compare the faces that will remain visible. A knot that suits a fence may be out of place beside closely fitted porch trim. Appearance grade belongs in that decision, alongside surface finish, rather than standing in for a structural rating.

Plan the finish along with the post purchase. Stain or sealant helps protect cedar against moisture and ultraviolet exposure. Montana’s UV at elevation and temperature swings make finish upkeep part of owning exposed wood. Inspect the exposed faces regularly and plan to renew the finish every few years according to exposure and condition.

Western Red Cedar Lumber 4x4: Species and Moisture Matter

Western Red Cedar is Thuja plicata, a softwood that grows in the Pacific Northwest. Eastern Red Cedar is Juniperus virginiana. They are different species, so use the full species name when comparing red cedar posts.

Western Red Cedar 4x4 posts come in smooth and rough forms, including Select Knotty appearance grade, abbreviated STK. Choose the smooth surface for a planed appearance and rough texture for exposed work where you want the saw texture to show. Keep species, grade and surface finish separate in the comparison.

Moisture condition deserves equal attention. S-GRN means surfaced green; that lumber will shrink and may cup or twist as it dries. KD-19 means kiln-dried to 19 percent moisture content or less. For close-fitting trim and joinery, favor dried stock. For green stock, allow for drying movement in the work rather than fitting everything tight around its fresh dimensions.

Keep cedar in a cool, dry place while it waits for the job. That is especially useful during Montana’s spring repair season, when you may buy material before the ground and weather are ready.

The Pick

Buy WBC’s 8-foot cedar appearance post surfaced on four sides for fence and railing projects whose full post cuts fit within 8 feet. Buy the 10-foot version for longer pergola, gazebo or fence-post cuts that need the extra 2 feet. Choose between them by the cut length, then match the actual cross section, species and moisture condition to the job.

Frequently Asked Questions

What are cedar 4x4 posts used for?

Cedar 4x4 posts are used for fences, railings, pergolas and gazebos, especially where the wood stays visible. The 8-foot and 10-foot smooth appearance posts give you two lengths to match to your finished cuts. Appearance grade describes the wood’s looks; it doesn’t establish the load capacity of a railing or roof support.

Is 4x4 cedar lumber actually four inches square?

A smooth cedar 4x4 can measure 3½ inches by 3½ inches, so a full four-inch opening can leave a loose fit. Use the finished measurement when laying out your joinery or fitting hardware. Rough-sawn texture doesn’t establish the size, either.

Can you paint or stain 4x4 red cedar posts?

Yes, smooth red cedar accepts paint or stain, and a protective finish helps limit moisture and ultraviolet damage. S4S means the post is planed on four sides; it doesn’t promise a sanded, finish-ready surface. Check the exposed faces for milling marks and follow your coating’s preparation directions before applying it.

Will Western red cedar 4x4 posts warp?

Western red cedar can warp, and green posts will shrink and may cup or twist as they dry. For close-fitting trim or joinery, dried material is the better starting point because green wood’s changing dimensions can spoil the fit. Keep your posts in a cool, dry place before installation, and allow for drying movement when working with green lumber.