Stair slabs

The usual form of stairs can be classified into two types: (1) those spanning horizontally in the transverse direction, and (2) those spanning longitudinally.

8.8.1 Stairs spanning horizontally

Stairs of this type may be supported on both sides or they may be cantilevered from a supporting wall.

Figure 8.17 shows a stair supported on one side by a wall and on the other by a stringer beam. Each step is usually designed as having a breadth b and an effective depth of d = D/2 as shown in the ligurc: a more rigorous analysis of the section is rarely justified. Distribution steel in the longitudinal direction is placed above the main reinforcement.

Details of a cantilever stair are shown in figure 8.18. The effective depth of the member is taken as the mean effective depth of the section and the main reinforcement must be placed in the lop of the stairs and anchored into the support. A light mesh of reinforcement is placed in the bottom face to resist shrinkage cracking.

Waist Reinforcement Stair

Figure 8.18

Canlilevered stairs

Figure 8.18

Canlilevered stairs

Main reinforcement

Light mesh h-


8.8.2 Stair slab spanning longitudinally

The stair slab may span into landings which span at right angles to the stairs as in figure 8.19 or it may span between supporting beams as in figure 8.20 of example 8.10.

The permanent load is calculated along the slope length of the stairs but the variable load is based on the plan area. Loads common on two spans which intersect at light angles and surround an open well may be assumed to be divided equally between the spans. The effective span (/) is measured horizontally between the centres of the supports and the thickness of the waist (h) is taken as the slab thickness.

Main reinforcement

Cantilever Stair Plan

Light mesh

Section B-B

Light mesh

Section B-B

Concrete Stair Reinforcement Design

Stair slabs which are continuous and constructed monolithically with their supporting slabs or beams can be designed for a bending moment of say Fl/10. where F is the total ultimate load. However, in many instances the stairs are precast or constructed after the main structure, pockets with dowels being left in the supporting beams to receive the stairs, and with no appreciable end restraint the design moment should be Fl/8.

Design of a stair slab

The stairs are of the type shown in figure 8.20 spanning longitudinally and set into pockets in the two supporting beams. The effective span is 3 m and the rise of the stairs is 1.5 m with 260mm treads and 150 mm risers. The variable load is 3.0 kN/nv and the characteristic material strengths are /ck 30N/mnr and/>* = 500N/mnr.

Try a 140 mm thick waist, effective depth. <1 115 mm. This would give an initial estimate of the span-effective depth ratio of 26.1 (3000/115) which, from table 6.10. lies a little above the basic value for a 'lightly stressed' simply supported slab.

Figure 8.20

Stairs supported by beams

Was this article helpful?

+1 -1
Greener Homes for You

Greener Homes for You

Get All The Support And Guidance You Need To Be A Success At Living Green. This Book Is One Of The Most Valuable Resources In The World When It Comes To Great Tips on Buying, Designing and Building an Eco-friendly Home.

Get My Free Ebook


  • Faramond
    What is the depth of stair slab?
    8 years ago
  • ortensia
    What is a waist on a stair?
    7 years ago
  • simon russom
    What is the waist on a staircase?
    7 years ago
  • einojuhani
    What is the span to depth ratio of a concrete stair case?
    7 years ago
  • demi
    7 years ago
  • nestore
    What is a continuous slab stair?
    4 years ago
  • Amanuel
    How much thickness of staire slab?
    4 years ago
  • christina furst
    What should be the thickness of waistslab concrete staircase.?
    3 years ago
  • Kalimac
    What is thw span/depth ratio for calculation of stairs?
    3 years ago
  • nairn
    How to design a stair in slope slab?
    3 years ago
  • belinda
    How to determine waise slab thickness of stair?
    3 years ago
  • Telma
    Can an open well staircase landing beam suspended as cantilever?
    3 years ago
  • scott
    How to calculate average slab thikness of stair?
    3 years ago
  • arnor
    How to staircase slap thickness?
    3 years ago
    What is effective end restaint in stairs?
    3 years ago
  • Farrah
    What is the waist in stairs?
    3 years ago
    What is pockets and dowels being left in supporting beams to receive staircases?
    2 years ago
    How to calculate average depth in stair case analysis?
    2 years ago
  • Mike
    What is waist slab thickness of stairs?
    2 years ago
    How to calculate staircase load?
    2 years ago
  • zak kennedy
    How to design two way stair case eurocode?
    2 years ago
  • aila
    Is standard of staircase slab thickness?
    2 years ago
  • tove
    How to design structural design of stair case?
    2 years ago
  • tellervo
    What is waist on concrete stairs?
    1 year ago
  • Mary
    How can design waist of stair?
    1 year ago
  • michelle
    How thick should the waist of a staircase be?
    1 year ago
  • emmie
    How to calculate the waist slab in staircase by thumb rule?
    12 months ago
  • Askalu
    How to give slab for staircase?
    10 months ago
  • maximilian freud
    How thick is a step eurocode?
    9 months ago
  • gabriel
    How to determine depth of landing slab?
    3 months ago
  • katharina zimmerman
    How to calculate stair case load in eurocode?
    3 months ago

Post a comment