Wood Siding

Wood siding lives or dies on two decisions made before a single board goes up: what species you buy and how you manage moisture during install. The panel itself matters less than most people think. Red cedar remains the wood siding material of choice due to the natural decay resistance of the heartwood and its attractive appearance when stained or finished clear. That’s the safe bet in a climate that swings wet to dry and cold to hot all year.

Here’s the split every buyer needs to understand first. There are three general categories of wood siding commonly used in construction. These are lumber, plywood, and reconstituted wood products such as hardboard and particleboard. Lumber covers your bevel, drop, shiplap, and board-and-batten boards. Plywood means the grooved sheet goods. They install and perform differently, so pick the family before you pick the product.

Species and Grade — The Choices That Actually Matter

Species is the longevity decision. Other decay-resistant woods are popular in the regions where they are produced: for example, redwood on the West Coast and cypress in the Southeast and Gulf Coast. Those heartwoods resist rot on their own. The cheaper route comes with strings attached. On projects where premium wood species are not affordable, builders also use a wide variety of softwoods, including pine and spruce, which are not naturally resistant to decay.

That’s the catch. Pine and spruce cost less up front but demand discipline on the finish. Most suppliers of wood siding now recommend back-priming and priming of cut ends, and these details are even more critical with the less decay-resistant species. Skip the back-prime on cedar and you’ve shortened its life. Skip it on pine in a wet valley and you’re looking at early failure.

Grade is a different conversation entirely. It’s about looks, not strength. Since wood siding is a nonstructural application, grading is generally for appearance only and is not governed by building codes. Most western species used for siding are graded according to one of the established grading agencies such as the Western Wood Products Association (WWPA). Here’s where buyers get burned: manufacturers are free to name the grades as they choose for marketing purposes. So one company’s “Select” grade may be quite different from another’s. For this reason, it is best to examine the material before specifying or purchasing. Look at the boards. Don’t trust the stamp alone.

Cedar bevel siding shows up in the Western Building Center stock list — an 11/16-inch by 8-inch board in 16-foot lengths, 3-and-better grade, kiln dried. Premium grade, the kind you’d field-finish clear or stain and expect to show off the grain.

Profile	Notes
Bevel / clapboard	For houses, bevel siding is perhaps the most widely used.
Drop / shiplap	Used especially on buildings without sheathing.
Board-and-batten	Vertical siding — tongued-and-grooved or square-edged boards applied vertically, often with narrow strips called battens nailed over the joints.
T1-11 plywood	Grooved siding products installed in 4’ x 8’ sheets, widely used throughout the U.S. since the 1970’s.

In western states the heavier profiles like channel rustic run more common than the thin clapboards you see back East. As for the grooved sheet goods — Plytanium plywood exterior siding comes as T1-11, Reverse Board & Batten, or No Groove, with grooves spaced 4 or 8 inches on-center for T1-11 and 12 inches on-center for RB&B. It’s Southern Yellow Pine, APA-certified, in 11/32 and 19/32 thicknesses. One thing on plywood: for siding it should have a rough sawn surface or be overlaid with medium density paper overlay (MDO). Smooth sanded plywood is not recommended for siding, but it may be used for soffits.

Moisture-Managed Installation — Where Rot Is Won or Lost

This is the section that matters most, and it’s been proven the hard way. Build test fences, let siding weather for years, and the lesson cuts straight to install practice: poor performance comes when the bottom of a piece of wood sits in contact with another surface, and the gap behind siding performs unusually poorly. You see it in the wood itself — extensive water staining on the backs of the boards caused by water travelling upward from the bottom edge.

That bottom edge is the enemy. In snow country, that’s exactly where siding meets snowpack for weeks at a stretch. Keep it off everything. Six inches of ground clearance, no contact.

Edges and ends drink water faster than faces. Plywood, hardboard and particleboard all tend to absorb moisture through the ends and edges of the panel faster than through the surface. So seal them. If the panel faces are to be primed and painted, apply the same finish to the edges. Any edges which are cut during construction should also be sealed. The same logic drives back-priming every board — all six surfaces — before it ever hits the wall.

Fasteners aren’t an afterthought either. Ferrous nails can leave unsightly rust stains on plywood and other board products. Use high quality galvanized nails on surfaces to be painted. Aluminum, stainless steel or high quality galvanized nails should be used if a water-repellent preservative, water repellent or semitransparent penetrating stain is to be used.

Grain direction quietly decides how long your paint lasts. Edge-grained bevel siding will hold paint well. Flat grained lumber will not hold paint as well since it shrinks and swells more than edge-grained lumber and because wide, dark bands of latewood are frequently present. Boards move with the seasons — wood in heated homes tends to dry and shrink in the winter and gains moisture and swells in the warm summer months. Excessive dimensional change in wood consistently stresses a paint film and may result in early failure.

Finish and Maintenance Reality

Wood siding is not a finish-it-and-forget-it material. Plan on coming back. A coating choice up front sets how long you go between recoats.

Plywood and the dense-grained softwoods fight paint. Sanded and roughsawn plywood will develop surface checks, especially when exposed to moisture and sunlight. These checks, coupled with the flat grain pattern characteristic of nearly all plywood, can lead to early paint failure. These paint failures can be minimized by the use of top quality acrylic latex paint systems. Same story for southern yellow pine and some fir — paint will not hold well on these species, and penetrating stains are preferred.

The numbers on stain tell you what to expect:

Finish approach	Expected life
Two-coat penetrating oil stain, rough/weathered wood	As long as 10 years
Single coat penetrating stain, new wood	2–4 years, but succeeding coats will last longer
Water-repellent preservative	1–2 years

Why penetrating stains win on rough wood: unlike paints, semitransparent penetrating oil-base stains cannot check and peel from plywood surfaces. These stains penetrate the wood and do not form a continuous film or coating like paint. For the two-coat method, use two coats and apply the second coat before the first is dry. Refinishing later is easier than paint — excessive scraping and sanding are not required. Simply use a stiff bristle brush to remove all surface dirt, dust and loose wood fibers, and then apply a new coat of stain.

One safety note worth taking seriously. Sponges or cloths that are wet with oil-base stain are particularly susceptible to spontaneous combustion. To prevent fires, bury them, immerse them in water, or seal them in an airtight container immediately after use.

Frequently Asked Questions

Which wood species lasts longest for siding? Western red cedar, redwood, and cypress carry natural decay resistance in the heartwood. Red cedar remains the wood siding material of choice due to the natural decay resistance of the heartwood and its attractive appearance when stained or finished clear. Pine and spruce cost less but aren’t naturally rot-resistant and lean hard on diligent finishing to hold up.

Does the grade name tell me how strong the siding is? No. Since wood siding is a nonstructural application, grading is generally for appearance only and is not governed by building codes. And grade names aren’t standardized between manufacturers, so one company’s “Select” can differ from another’s. Inspect the actual boards before you buy.

Why does the bottom edge of siding matter so much? The bottom of a piece of wood that sits in contact with another surface performs poorly. Water wicks upward from that edge into the board, leaving extensive water staining on the backs of the boards caused by water travelling upward from the bottom edge. Keep the bottom edge off everything and maintain ground clearance.

Should I paint or stain wood siding? Depends on the surface. Smooth, edge-grained boards hold paint well. Paint will last longer on smooth, edge-grained surfaces. Penetrating stains or preservative treatments are preferred for rough-sawn lumber. On plywood and dense-grained softwoods prone to checking, a quality acrylic latex paint or a penetrating stain outperforms oil-based paint.

Can I use smooth plywood for siding? Not recommended. Exterior plywood with a rough sawn surface is commonly used for siding. Smooth-sanded plywood is not recommended for siding, but it may be used in soffits. Rough-sawn or MDO-overlaid plywood is the standard for exterior siding.

How often will I need to refinish? Plan on it as part of owning wood siding. A two-coat penetrating oil stain on rough wood can run up to 10 years, while a single coat on new wood lasts only 2 to 4 years. Climate and coating type drive the schedule — at elevation, UV and freeze-thaw push you toward the shorter end.