# Civil Engineering - RCC Structures Design - Discussion

Discussion Forum : RCC Structures Design - Section 2 (Q.No. 4)
4.
For stairs spanning horizontally, the minimum waist provided is
4 cm
6 cm
8 cm
10 cm
12 cm.
Explanation:
No answer description is available. Let's discuss.
Discussion:
26 comments Page 1 of 3.

Spanning horizontally is nothing but considering the design as a horizontal slab. Waist slab is the minimum distance of the stair upper surface to the lower slab bottom. That can be decided by the design. But for an RCC minimum slab width must be greater than 3.5 inches so we can say 80 mm.

Manish sahu said:   7 years ago
@Ali Baloch.

Spanning horizontally means horizontal member length and waist slab is that on which rise and tread constructed.

Muhammad Tabish said:   2 years ago
The waist is the thickness of an inclined slab and it is considered 8cm for the stair spanning horizontally

Uttam said:   6 years ago
Yes it should be 8 cm.
Ref: R.S. Khurmi/ conventional and objective type civil engineering book.
(1)

Hesan said:   7 years ago
Minimum width of stair 90 cm.
so minimum width of the waist will be 90cm.

Ali Baloch said:   7 years ago
What is meant by spanning horizontally and what is meant by waist? Please explain.

Vkey said:   8 years ago
Exactly @Savita. Minimum thickness of waist slab should be 80mm.

Suman Khadka said:   5 years ago
It should be equal to slab thickness so 120 mm is correct.

Munna said:   7 years ago
The waist slab always 150mm,