Skip to main content

Types Of Level In Construction

Complete Guide to Construction Levels

Complete Guide to Construction Levels with Practical Explanations

In construction and civil engineering, different levels are used to ensure proper alignment, stability, drainage, and functionality. Below is a step-by-step explanation of each level in logical order, with practical examples to help you understand them better.

1. Natural Ground Level (NGL) – The Original Surface

Definition: The existing level of the ground before any excavation or filling.

Practical Example: Imagine you buy land with an uneven surface. The NGL is the starting point before any construction activity.

Why It’s Important?

  • Used as a reference for leveling, excavation, and filling.
  • Helps determine how much soil needs to be removed or added.

2. Existing Ground Level (EGL) – After Site Preparation

Definition: The level of the ground after site clearing, but before excavation.

Practical Example: After removing trees, bushes, and debris, engineers measure EGL to plan further construction.

Why It’s Important?

  • Helps assess how much the ground needs to be raised or lowered.
  • Used in road construction and site grading before laying foundations.

3. Building Ground Level (BGL) – The Final Ground Level Around the Structure

Definition: The final ground level around the building after excavation, filling, and compacting.

Practical Example: After site preparation, engineers ensure that BGL is slightly sloped away from the building to allow rainwater drainage.

Why It’s Important?

  • Prevents waterlogging and foundation damage.
  • Ensures proper landscaping and pathways around the building.

4. Plinth Level – The Raised Base of the Structure

Definition: The level at which the main building structure starts, raised above BGL.

Practical Example: If a house is built at ground level without a plinth, rainwater could enter inside. To prevent this, a plinth is raised 300mm to 600mm above BGL.

Why It’s Important?

  • Protects the structure from moisture, water damage, and termites.
  • Acts as the base for the walls and foundation stability.

5. Invert Level – The Bottom of Drainage Pipes

Definition: The lowest internal surface of a pipe, sewer, or drainage channel, which determines water flow direction.

Practical Example: If a sewer pipe is 1 meter in diameter, the invert level is at the lowest point inside the pipe (not the top).

Why It’s Important?

  • Prevents water stagnation and blockages in drainage systems.
  • Helps design sewage and stormwater disposal systems with proper slopes.

6. Structural Floor Level (SFL) – The Base Floor Before Finishing

Definition: The level of the concrete slab before applying flooring materials like tiles or wood.

Practical Example: A reinforced concrete slab is laid at SFL. Later, finishing materials like tiles are added on top.

Why It’s Important?

  • Provides a strong structural base for flooring.
  • Helps in load distribution for buildings.

7. Floor Finish Level (FFL) – The Final Floor Height

Definition: The level of the floor after applying finishing materials like tiles, marble, or wooden flooring.

Practical Example: If a tile is 20mm thick, the FFL will be 20mm higher than the SFL.

Why It’s Important?

  • Determines the final room height and door frame alignment.
  • Ensures a smooth and level walking surface.

8. Sill Level – The Bottom of Windows

Definition: The height at which a window starts above the floor.

Practical Example: In most houses, the window sill level is 750mm above the floor, allowing a comfortable view while standing.

Why It’s Important?

  • Ensures proper ventilation and natural lighting.
  • Prevents accidental falls from windows.

9. Lintel Level – Support Above Doors & Windows

Definition: A horizontal beam placed above doors and windows to support the wall above.

Practical Example: Without a lintel, the bricks above a door frame would collapse due to lack of support.

Why It’s Important?

  • Prevents cracks around doors and windows.
  • Adds structural strength to openings.

10. Freeboard Level – Safety Margin for Water Overflow

Definition: The distance between the maximum water level and the top edge of a structure (such as a dam, tank, or drain).

Why It’s Important?

  • Prevents flooding and overflow damage.
  • Ensures safe operation of water structures.

11. Water Level – The Height of Water in a Structure

Definition: The level at which water naturally settles in a tank, river, dam, or drainage system.

Why It’s Important?

  • Helps design water storage, drainage, and flood control systems.
  • Ensures proper water flow in pipes and canals.

12. Roof Level – The Highest Part of the Building

Definition: The level where the roof slab or truss system is placed.

Why It’s Important?

  • Protects the building from rain, wind, and heat.
  • Defines the total height of the structure.

13. Contour Level – Elevation of Land Surface

Definition: Represents points of the same elevation on a site or map.

Why It’s Important?

  • Helps in site grading, drainage planning, and foundation design.
  • Used in topographic surveys to plan roads and canals.

14. Master Level – The Primary Reference Level

Definition: A fixed reference level from which all other levels are measured in a project.

Why It’s Important?

  • Ensures uniformity and accuracy in large-scale projects.
  • Acts as a permanent reference point during construction.

15. Road Level (RL) – The Finished Road Height

Definition: The level at which the finished surface of a road is constructed.

Why It’s Important?

  • Ensures proper drainage and vehicle movement.
  • Determines curb heights, footpaths, and connectivity.

Final Summary – Complete Step-by-Step Order

  1. NGL → Natural ground before any site work.
  2. EGL → After site clearing.
  3. BGL → Final ground level around the building.
  4. Plinth Level → Raised base above BGL.
  5. Invert Level → Bottom of drainage pipes.
  6. SFL → Structural concrete slab before flooring.
  7. FFL → Finished floor height.
  8. Sill Level → Bottom of windows.
  9. Lintel Level → Support above doors/windows.
  10. Freeboard Level → Safety margin for water.
  11. Water Level → Height of stored/flowing water.
  12. Roof Level → Top of the building.
  13. Contour Level → Used for land elevation.
  14. Master Level → Main reference for measurement.
  15. Road Level (RL) → Final road height.

Comments

Popular posts from this blog

GENERAL NOTES AND STANDARD DETAILS ( FOR RCC CONSTRUCTION) MISCELLANEOUS TYPICAL DETAILS PDF

General Notes and Standard Details for RCC Construction General Notes and Standard Details for RCC Construction Miscellaneous Typical Details (Sheet 3 of 3) Thank you for downloading and viewing this drawing! If you find this drawing helpful, please consider sharing it and subscribing to Afroz Civil on our website and YouTube channel for the latest updates. We strive to provide valuable resources for site engineers , ensuring practical and insightful information to support your projects. Stay connected as we regularly share expert knowledge and real-world experiences to help you succeed in the field. Get Involved! ✅ Download this drawing in PDF ✅ Join Our YouTube Channel ✅ Join Our Civil Engineering Construction Update Your Feedback Matters! We continuously update our platform with helpful information and share practical experiences to support your work. Please leave your valuable feed...

TEST REPORT of DESIGN MIX M-30 & M-25

        Sample -1 M25          Sample -2 M25              Sample -3 M25            Sample -1 M30 Sample -2  M30

What is Chair Reinforcement in Building Construction ?

Chair Bar Guidelines for Reinforcement Chair Bar Guidelines for Reinforcement (As per IS Code) 1. Purpose of Chair Bars Chair bars are used to hold the reinforcement bars in position during construction to prevent displacement while pouring concrete. They ensure the required spacing is maintained between the top and bottom reinforcement bars as per design specifications. 2. Spacing of Chair Bars As per IS 456:2000 – Plain and Reinforced Concrete Code of Practice : Chair bars should be spaced at nominal 1000 mm centers , unless specified otherwise. For heavily reinforced slabs or where vibration may cause displacement, spacing can be reduced to 600-800 mm . 3. Diameter of Chair Bars As per IS 2502:1963 : The diameter of a chair bar is recommended as hc/50 , where hc is the clear cover. The diameter should not be less tha...