How much wood for a garden bench?
A 48″ outdoor bench: 8/4 walnut frame with 4/4 white oak slats — the mixed-species example from our mockups, sized for two.
Parts total 14.5 BF; with 15% waste you'd buy 16.7 BF — about $139.67 at our 2026-08 price estimates, weighing roughly 58 lb.
Cut list
| Part | Species | Qty | Thick | W × L | BF |
|---|---|---|---|---|---|
| Legs | Black Walnut | 4 | 8/4 | 3″ × 18″ | 3.00 |
| Aprons | Black Walnut | 2 | 4/4 | 5″ × 48″ | 3.33 |
| Stretchers | Black Walnut | 2 | 6/4 | 2.5″ × 42″ | 2.19 |
| Seat slats | White Oak | 6 | 4/4 | 3″ × 48″ | 6.00 |
Cost by species
| Species | Buy (BF) | $ / BF | Cost |
|---|---|---|---|
| Black Walnut | 9.8 | 9.50 | $93.09 |
| White Oak | 6.9 | 6.75 | $46.57 |
White oak is the honest outdoor choice; walnut holds up with finish and cover. For full weather exposure, swap the walnut for more white oak or cypress.
Why it's built this way
Outdoor joinery lives or dies at the end grain: water wicks up unsealed end grain ten times faster than through faces, so every apron shoulder and leg bottom gets sealed, and the leg bottoms sit on nylon glides rather than wet stone. Drawbored mortise-and-tenon joints — pegs driven through slightly offset holes — stay tight through wet-dry cycles that loosen glued joints; it's how park benches from the 1920s are still standing. Gap the seat slats 1/8″ so water drains instead of ponding.
At the lumberyard
This build is also a price lesson: at seeded prices the walnut-and-oak bench runs about $140 in lumber, while the same bench in teak would top $500 — and in pressure-treated pine, about $40, if you can live with the look. White oak (never red — its open pores drink water) is the durability-per-dollar winner for outdoor furniture. Use stainless or silicon bronze fasteners: plain steel plus oak tannins equals black stains around every screw.