What changes outdoors
Indoors, wood stays at a fairly steady moisture content. Outdoors it is wetted by rain and dew, dried by sun and wind, and attacked at the surface by ultraviolet light, which the Wood Handbook names as the start of weathering. None of that makes wood rot on its own. The Handbook is precise about decay: it needs the wood's moisture content above the fibre saturation point, on average about 30%, which happens only when liquid water reaches the wood — rain, condensation or wet ground. Wood kept air-dry, usually 20% or less, does not decay. Every choice below comes back to that: pick wood that resists decay when it does get wet, and design so it does not stay wet.
Choosing wood that lasts
| Group | Examples | Where the Handbook says it generally serves |
|---|---|---|
| Very resistant | Black locust, osage-orange, red mulberry, Pacific yew | In contact with the ground |
| Resistant | Cedars (western redcedar, eastern redcedar, Atlantic white, incense, northern white, Port-Orford, yellow), white oaks, black walnut, old-growth redwood, junipers | Above ground |
| Moderately resistant | Douglas-fir, western larch, black cherry, honey locust, young-growth redwood, old-growth eastern white pine | Usually needs preservative treatment where decay can occur |
| Slightly or nonresistant | Most pines, spruces, true firs, hemlocks, maples, birches, ashes, yellow-poplar | Usually needs preservative treatment where decay can occur |
Heartwood only, from the Wood Handbook's Table 14-1. Resistance is lower in ground contact and in warm, humid climates, and varies widely within a species.
- Heartwood, not sapwood. The Handbook says untreated sapwood of essentially all species has low resistance to decay, and that much second-growth lumber contains a high proportion of sapwood. A 'cedar' board with pale sapwood along one edge is not all resistant wood.
- Match the group to the exposure. Resistant heartwood generally gives satisfactory service above ground; for ground contact the Handbook points to very resistant heartwood or, for severe conditions, pressure-treated wood. That is why cedar suits the chair, the planter and the nest box here.
- Expect variation. The Handbook warns that precise ratings are not possible: pieces from the same species, even the same tree, can last very differently.
Many cedar wood projects are small — the planter and nest box below each use only a few boards — which makes clear heartwood easier to choose. Boards are sold by nominal size and dressed smaller, so measure what you buy; choosing lumber covers grades and defects.
Pressure-treated lumber
- Read what comes with it. The Handbook says EPA-approved Consumer Information Sheets accompany some treated-wood products and cover their use and disposal; follow the treater's information for the product you buy.
- Today's preservatives are not CCA. The EPA says CCA-treated wood was discontinued for most residential uses at the end of 2003.
- Never burn the offcuts. The EPA says preservative-treated wood should not be burned in a residential setting, because of the chemicals in the smoke and ash.
- Treat what you cut. The Handbook says cut ends and drilled holes in treated wood need supplemental treatment on site.
- Choose fasteners for it. Waterborne preservatives can promote fastener corrosion; see the next section.
BenchRoot makes no claim about treated wood in contact with food or soil for food plants; the product's own information is the place to look.
Designing so wood dries
- Keep end grain off the ground. The Handbook calls end grain butting a horizontal surface high risk; legs and post ends sitting in water rot first. Set feet on pads or keep a gap below.
- Leave gaps. Slats and boards with gaps between them shed water and dry; they also leave room for the movement the Handbook describes, which is far greater across the grain than along it.
- Seal end grain. Liquid water enters end grain 10 to 100 times faster than other faces, the Handbook says, so sealing it is critical.
- Do not let wood sit in water. Leave space below the bottom edge of any board exposed to weather, and slope or bevel surfaces that would otherwise hold water.
Fasteners and glue
- In treated wood, choose the metal. The Handbook says fasteners can corrode in moist contact with some preservative treatments, and that 300-series stainless steel has performed well in wood treated with copper azole and alkaline copper quaternary. Follow the fastener maker's rating for the treatment you use.
- In cedar and oak, avoid stains. Extractives in some woods stain steel when wet; the Handbook says stainless steel, aluminum or hot-dipped galvanized nails alleviate it.
- Do not mix metals. A connector and its fasteners should be the same metal, or galvanic corrosion can speed up in one of them.
- Glue for the conditions. A glue rated ANSI/HPVA Type I, such as Titebond III, is water-resistant, but its maker says it is not for continuous submersion. Outdoor joints in these plans are screwed or bolted as well; gluing wood covers glue-ups.
Finishing outdoor work
The Handbook describes how unprotected wood weathers: ultraviolet light breaks down the surface, and wood that has turned silver or grey is severely sunburned and needs sanding before a film finish will hold, while a penetrating finish lasts longer on weathered wood. Which exterior finish to use is a separate question, covered in wood finish types, exterior wood stain, outdoor primer and paint and choosing a wood finish. Nest boxes are the exception: NestWatch says to leave them unpainted, as the nest box plan explains.
The outdoor plans
| Plan | Level | Stock | What it teaches | Outdoor point to watch |
|---|---|---|---|---|
| Planter box | Beginner | ¾ in cedar boards, 2×2, 1×2 | A box with posts, cleats and a slatted floor | Soil keeps the wood wet; lift it off the ground |
| Nest box | Beginner | ¾ in cedar boards | Sloped roof, recessed floor, a pivoting side | Untreated, unpainted wood; size the hole to the bird |
| Adirondack chair | Intermediate | ¾ in cedar boards | Angled rails and a reclined back from straight cuts | Rail ends on the ground; seal them |
| Picnic table | Intermediate | 2×6 and 2×4 lumber, carriage bolts | A bolted A-frame with attached seats | Fasteners matched to the wood; level ground |
All four are BenchRoot designs, drawn and checked but not built for these pages; none is load-rated.
Board feet for the stock are worked out with the board foot calculator and lengths with the lumber calculator. Indoor seating is covered by the bench plan and the stool plan.
Safety— Treated wood and outdoor work
Follow the treated wood's consumer information when cutting it, collect its dust and never burn the offcuts. Protective equipment is covered in woodworking safety equipment, dust in the dust collector guide, and shop practice in woodworking safety rules.
Before starting an outdoor project
- Heartwood of a resistant species, or treated lumber with its consumer information
- Every part shaped to shed water; end grain off the ground
- Gaps for drainage and movement
- End grain to be sealed
- Fasteners matched to the wood and to each other
- A finish chosen from the finish guides, or none for a nest box
More project plans
Looking for a larger collection of woodworking project plans?
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Sources
Durability, preservatives, fasteners and weathering are as the Wood Handbook states them; species are grouped as its Table 14-1 groups heartwood, a selection of domestic woods shown. Finishing is left to BenchRoot's finish guides. The four plans are BenchRoot designs, drawn and checked but not built for these pages, with no load rating.
- 1.
Chapter 14: Biodeterioration of Wood. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: Serious decay only above the fibre saturation point (about 30% moisture content), air-dried wood at 20% or less giving a reasonable margin; Table 14-1 grouping heartwood by decay resistance, with lower resistance in ground contact and warm, humid climates and wide variation within species; sapwood of essentially all species low in resistance; resistant heartwood generally satisfactory above ground, very resistant in ground contact, the other groups usually needing preservative treatment; using heartwood, and second-growth lumber often high in sapwood.
- 2.
Chapter 15: Wood Preservatives. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: EPA-approved Consumer Information Sheets for some treated-wood products, covering use and disposal; 'restricted use' referring to the preservative, not the treated wood; waterborne preservative chemicals able to promote corrosion of fasteners; cut ends and drill holes in treated wood needing supplemental on-site treatment.
- 3.
Chromated Arsenicals (CCA). U.S. Environmental Protection Agency, 2025.
Used for: CCA-treated wood discontinued for most residential uses at the end of 2003, and CCA or other preservative-treated wood not to be burned in a residential setting.
- 4.
Chapter 8: Fastenings. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: Fasteners corroding in contact with some preservative-treated wood when moist, with 300-series stainless steel performing well in wood treated with copper azole and alkaline copper quaternary; connector and fastener of the same metal to avoid galvanic corrosion; extractives staining steel, alleviated by stainless steel, aluminum or hot-dipped galvanized nails.
- 5.
Christopher G. Hunt. Wood Handbook: Wood as an Engineering Material (FPL-GTR-282), Chapter 16: Finishing Wood. USDA Forest Service, Forest Products Laboratory, 2021.
Used for: Weathering started by ultraviolet light and worsened by water, temperature change and microorganisms; grey wood as severely sunburned, needing sanding before a film finish, while penetrating finishes last longer on it; liquid water entering end grain 10 to 100 times faster than other faces, so sealing end grain is critical; leaving space below boards so they do not stay wet; all decay starting with moisture.
- 6.
Chapter 4: Moisture Relations and Physical Properties of Wood. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: Wood changing in width with moisture content far more across the grain than along it.
- 7.
Titebond III Ultimate Wood Glue. Franklin International (Titebond).
Used for: A glue passing ANSI/HPVA Type I water resistance, which its maker says is not for continuous submersion.
- 8.
NIST Handbook 130 (2026), IV.B Uniform Regulation for the Method of Sale of Commodities. National Institute of Standards and Technology, 2026.
Used for: Softwood lumber sold by nominal size and dressed smaller, a nominal 1 × 6 dressed dry to 3/4 × 5-1/2 in.
About this guide
Written by BenchRoot Editorial. How BenchRoot sources, checks and corrects its pages is set out in the Editorial Policy. If something here is wrong or unclear, the contact page explains how to tell us.