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What is the slab thickness in building design ? minimum thickness of slab ?
Slab is a flat section which is perpendicular to the gravitational force. The slab section is helps to transfer the loading condition from various forces to beam and through that it will transfer to columns and finally to the foundation section. Depending upon the building design consideration the thickness of slab section changes. For basic ground floor building or G+1 building structures the slab is taken as 5” with minimum of M20grade concrete and Fe415 grade steel. While designing the slab section as per the code provisions the total loading which is related to the gravity loads and lateral loads is taken and the load combinations are assumed as per the specified code book.
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Slab thickness |
There are two types of slabs which are described below
- One way slab
- Two way slab
One way slab
The one way slab is the section which is generally used if the ratio of longer span to smaller span is greater than or equal to 2 factor. And the loading distribution will takes one direction in this case and the slab section is supported on two opposite sides.
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| One way slab cross section |
Two way slab
The two way slab is the section which is generally used if the ratio of longer span to smaller span is less than 2 factor. The slab is supported on the all the four sides in this case, loading distribution will takes all directions equally.
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| Two way slab cross section |
What is the slab thickness in building for various floors ?
The thickness for the building structure slab is depending upon the various factors like number of floors, total load, type of support, grade of the concrete, span length etc,
The following the various thickness of the slab section we will consider per standards. Please use these values only for education purpose for clearly understanding the concepts in slab design.
Minimum thickness is generally considered as four times of nominal size of coarse aggregates. Example if we take maximum coarse aggregates size is 20mm then we have to take 4X20=80mm minimum as per IS code provisions.
Note: Depending upon the various building design considerations the slab thickness varies.
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S. No |
Number of floors |
Building Height in meters |
Slab thickness |
|
1 |
Ground |
3m |
100mm |
|
2 |
G+1 |
6m |
125mm |
|
3 |
G+2 |
9m |
125mm |
|
4 |
G+3 |
12m |
150mm |
|
5 |
G+4 |
15m |
150mm |
|
6 |
G+5 |
18m |
150mm |
|
7 |
G+6 |
21m |
180mm |
|
8 |
G+7 |
24m |
180mm |
|
9 |
G+8 |
27m |
Depends upon various factors |
|
10 |
G+9 |
30m |
Depends upon various factors |
The slab thickness for various floors of building are explained in YouTube channel with detailed explanation please click here to see.
Conclusions for slab thickness in building for various floors
Well now the explained concepts are related to the slab thickness for various floors from ground floor to G+9 building designs. For single floor which is of 3m height building the minimum slab is 100mm, for two floors which is of 6m height building the minimum thickness is 125mm, for three floors which is of 9m height building the minimum thickness is 125mm, for four, five, six floors building which is of 12m, 15m, 18m height buildings the minimum slab thickness in building is 150mm, for the seven and eight floors building which is having 21m and 24m height minimum thickness is taken as 180mm and for the remaining floors the thickness will changes depending upon the various building design considerations.
The column dimensions for various floors is explained in my previous post please click here to read.
The beam dimensions for various floors is explained in my previous post please click here to read.
Please follow my YouTube Channel for more topics and concepts related to the civil engineering. If you have any Questions about the slab thickness for various floors in building feel free to reach us at contact us page.
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