Difference Between Plinth Level, Sill Level, Lintel Level | NGL & BGL


A Building consists of various types of levels. Details regarding different levels, like their dimensions, are usually shown in the auto CAD drawings. It makes the process of understanding, a lot easier for the engineers.

Types Of Levels In Building

The different types of levels of the building are as given below:

  • Plinth Level
  • Sill Level
  • Lintel Level
  • Natural Ground Level (NGL)
  • Building Ground Level (BGL)

All of these levels are provided in a structure to make it sound and stable. Let us learn about each one of them in detail below.

Plinth Level

The portion of superstructure which is located between the surrounding ground and the finished floor is known as the plinth. The level of floor is usually referred as the plinth level.

The primary objective of the plinth level is to terminate the access of moisture, dampness, and seepage of rainwater and stormwater inside the building. The height of plinth level usually ranges from 300mm to 450mm. The reference of its height is taken from natural ground level. The minimum height of plinth level is taken 150mm from the road level.

Functions Of Plinth Level

i) The functions of plinth level are as follows:-

ii) The plinth level protects the whole structure from dampness.

iii) It transfers the load from the superstructure to the substructure, maintaining the stability of the structure.

iv) It improves the aesthetical appearance of the structure.

v) It elements the risk of differential settlement of foundation up to a certain level.

Sill Level

The base portion of the window is made up of masonry elements. It is known as sill of window. The Sill level is defined as the height or vertical measurement between the finished floor level of the building and the base of the window. The sill level is found in windows only.

The height of sill level in living rooms and other rooms is kept between 600mm to 650mm whereas the height of the Sill level in the bathroom is kept a minimum of 1100mm. The height of sill level in bathroom is kept more due to privacy concerns.

Purpose Of Sill Level

i) To provide a rigid base to the window frame and the window as a whole. The base provides support to the window.

ii) To provide the smooth finished surface to the window.

iii) To prevent the entry of moisture.

Due to absence of sill, cracks may develop in the wall due to load coming on it. Also moisture may seep into the wall due to the absence of sill.

Lintel Level

Lintel is an element made up of Reinforced Cement Concrete (RCC) which is located at the top of the doors and windows (See above image). Unlike sill, the lintel is provided to the doors and windows both the major purpose of a lintel is to transfer the load, coming from the walls above to the surrounding wall area.

The frame of the door is not capable for bearing the load coming from the wall above it. So, it is necessary to provide a lintel to doors and windows. As per the building regulations, the preferred lintel height for the residential building is 2.1m and for the commercial building is 2.3m.

Natural Ground Level (NGL)

The Natural Ground Level (NGL) is defined as the level of the ground or land in its unmodified state. The height for Natural Ground Level (NGL) is generally measured with the reference of Mean-Sea Level (MSL). The ground’s level is measured in its original state without any disturbance on it such as excavation (cutting) or filling.

Building Ground Level (BGL)

The level of land or the finished floor level inside the building is known as the Building Ground Level (BGL). The height of the Building Ground Level usually ranges from 150mm to 450mm, from the Natural Ground Level (NGL).

One main reason for raising the height of any building is to restrict the entry of water inside the building due to rainfall or storm. The height of the Building Ground Level may increase if the building is located in sloppy areas as well as in the areas where heavy rainfall is commonly seen.

Also Read –

Difference Between Plinth Beam & Tie Beam

Types Of lintels Used In Building Construction

Types Of Buildings – Detailed Classification

If you like this article then please share it with your friends & also like our Facebook Page and join our Telegram Channel.

1 thought on “Difference Between Plinth Level, Sill Level, Lintel Level | NGL & BGL”

Leave a Comment

error: Content is protected !!