Raised Planter on a Deck – Structural Concerns

4-ft High, 4-ft Deep Planter Attached to Deck

User wants to fill bottom with scrub wood, then 12 inches of soil, accessed from deck.

Engineering Reality

• Soil weighs ~100 lbs/ft³. A 4×4×4 ft planter = 64 ft³ = 6,400 lbs + lumber. Most decks cannot support this.
• Organic fill (scrub wood) will decompose, settle, and harbor pests.
• Planter must be lined with rubber to prevent rot.
• Lightweight soil mix reduces load but still heavy.

Better Approach

Use 18-inch wide planting boxes attached to deck rails, or extend the deck. If a large planter is essential, consult a structural engineer.