Floor slab

A floor slab is the horizontal structure we walk on. It takes the weight of furniture, people and itself, and passes those loads through beams, columns or load-bearing walls down to the foundations. It also separates storeys, limiting the passage of fire, sound and heat between them. In Turkish the word döşeme can also mean the floor finish on top, but in structural terms it refers to the slab itself.

Main slab types

In reinforced concrete buildings the most common systems are beam-and-slab, flat slabs without beams, and ribbed or waffle slabs with lightweight infill blocks. Flat slabs give a clean ceiling and freedom for services, while beam-and-slab systems can be more economical over longer spans. Steel buildings often use composite slabs cast on profiled metal decking, and timber buildings use joisted floors or cross-laminated timber panels.

Architectural decisions around the slab

• Slab depth feeds directly into floor-to-floor height and the clear ceiling height that remains.
• Bathrooms and other wet areas may need a set-down or falls planned into the slab early.
• Floating screeds and acoustic layers cut impact noise reaching the floor below considerably.

In sectional perspectives the slabs are the clearest way to show how a building is layered. Keeping slab thickness true to size in a visualisation model also makes stairs, windows and ceiling details sit correctly.