Plinth Level & Sill Level

The plinth level is the portion of the superstructure between the top of the tie beam on the floor level (the top layer of soil surrounding the structure that has been prepared and leveled earlier than construction) and the floor level of the building( the ground floor level inside the building).

The plinth height is actually provided to guard the superstructure from dampness attributable to direct contact with the ground.

The top of the plinth level is provided with a damp proof course which is an additional protection against moisture.

In heavy rains seasons, the height of the plinth also prevents stormwater/overflowing drainage from entering the building directly.

Typically, the plinth level is provided approximately 300-450 mm above the ground level.

It is suggested that the plinth level should be fixed considering the top of the road, the former should be kept at least 150 mm higher.

Functions of Plinth Level:

The major functions of the plinth level can be listed as follows:

  • Along with the structural elements it prevents the building from completely leaking moisture.
  • It acts as a medium to transfer the load coming from the superstructure to the bottom of the foundation.
  • It enhances the aesthetic appearance of the building.
  • Also acts as a retaining wall and retains backfill soil.
  • This minimizes the risk of settlement of the foundation gap.

Sill Level or Window Sill Level:

The level between the base of the building’s window and the floor level above the ground level is called the sill level.

Sill is the base of the window i.e. the level from the floor of the room to the window starts (goes upwards), the concrete bed or mortar bed is placed on the base level of the window, granite can be used on the base level of the window.

The height of the sill level varies from room to room and will depend on the kind of room.

Typically for bedrooms, a height of 1100 mm is adopted due to privacy, while a drawing-room usually provides a height of 400–850, while minimum required height of the sill level should be 44 inches.

Also read: Difference between Tie Beam and Plinth Beam

Difference between Plinth and Sill Level:

Plinth LevelSill Level
It is the part of the superstructure that lies between the natural ground level and the completed ground level.It is part of the superstructure that lies between the lower base part of the window and the finished floor level.
A beam is normally produced on the plinth level such a beam is called a tie beam.A mortar bed or cement concrete bed is usually laid at the sill level.
The height of plinth above natural ground level is usually kept between 300 mm to 450 mm. The height of the sill level is maintained b on the type of room.
Generally, 600 mm height is adopted for bedrooms (2.5 is usually placed) and for the bathroom minimum of 1100 mm is adopted.
Also, read: Plinth Protection, Moment Frame & Parts of a door


The height of the sill and lintel level from the floor level depends entirely on the dimensions of the door and window openings.

Typically, the sill level is kept above 0.5 –1 m above the floor level for the partition wall and 1.5–2 m above the level in the render walls.

Hello, I'm Rahul Patil founder of, I had studied B.E. Civil. This blog provides authentic information regarding civil structures, equipment, materials, tests & much more.

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