Deck Stair Building Guide
Everything you need to know about building stairs for your deck, from planning and code requirements to construction details.
Deck Stair Basics
Deck stairs differ from interior stairs in several ways: they're exposed to weather, they require a concrete landing pad, stringers must be pressure-treated or naturally rot-resistant lumber, and they attach to the deck rim joist rather than interior framing. Most decks are 24-60 inches high, resulting in 3-8 steps.
Landing Pad Requirements
Most codes require a concrete landing pad at the bottom of deck stairs. The pad should be at least 36" × 36" (or matching the stair width), 4" thick, poured on 4-6" of compacted gravel. In cold climates, the pad should extend below the frost line or use a thickened edge. The pad must extend at least 36" from the bottom riser.
Stringer Attachment to Deck
Stringers connect to the deck rim joist using one of two methods: stringer hanger brackets (preferred) or a 2×4 ledger board bolted to the rim joist that the stringers rest on. Use hot-dipped galvanized or stainless steel hardware for all outdoor connections. The top of the stringer typically sits one riser height below the deck surface.
Material Considerations
- Stringers: Always use pressure-treated 2×12 for outdoor stairs.
- Treads: Match your deck surface — composite, pressure-treated, or cedar. Use two 5/4×6 boards per tread with 1/4" gap between.
- Risers: Open risers are common on deck stairs. If closed, use pressure-treated 1× boards.
- Fasteners: All hardware must be rated for pressure-treated lumber (ACQ compatible). Use stainless steel or hot-dipped galvanized.