Concrete Base Options for an External Oak Staircase or Balcony

When building an external oak staircase or balcony, choosing the correct concrete foundation is essential for stability, drainage, and long-term appearance. Two common options are a full concrete plate or separate concrete pads.

A concrete plate offers the strongest and most practical solution. For external staircases, the slab should be:

• Option no 1: at least 100–150 mm thick, reinforced with mesh.
• Option no 2: at least 600 mm thick, without mesh. See video below.

Extend at least 300–400 mm beyond the footprint of the posts. This creates a clean, level surface that prevents mud splashing onto the oak posts. It also provides a dry, usable space beneath the stairs—perfect for storing logs, tools, or even building a small shed under the landing.

Concrete pads are a cheaper and quicker alternative. Each pad should typically be 450 × 450 mm and 500 mm thick, depending on soil conditions. Although structurally acceptable, pads have disadvantages: during rainy weather, mud can accumulate around the exposed posts, making them difficult to clean and less visually appealing. Pads also do not offer the practical, tidy storage space that a full slab provides.

For durability, easy maintenance, and better use of space, most homeowners prefer a full concrete plate for external oak staircases and balconies.