What Is Grading in Construction?
What Is Grading in Construction?
Grading is a process that involves preparing the land for construction by creating a level base or a specific slope. It is typically done as part of the site preparation process before construction starts.
The purpose of grading is to create a stable foundation for the structure, improve drainage, achieve desired aesthetics, and minimize environmental impact through proper water runoff and erosion control. It may also be necessary to comply with local rules and regulations.
During the grading process, the construction team shapes the surface of the land to achieve these objectives.
The proper grading of land during construction is essential in order to achieve the intended results of the project and avoid potential issues such as deviation from the architectural design, groundwater-related structural issues, and environmental harm due to inadequate drainage. It is a specialized aspect of the construction process.
Purpose Of Construction Grading
It is crucial to properly grade and prepare the site for construction projects, as this can affect not only the structure being built, but also neighboring buildings and homes.
Inadequate grading can lead to water runoff flowing towards the building, causing structural damage due to hydrostatic pressure and potentially creating liability for the builder or owner if it causes damage to other properties.
It can also lead to erosion and damage to the property itself. To prevent these issues, many planning and zoning authorities require approved grading plans before construction can begin, in order to ensure compliance with land grading standards.
Site grading not only helps with drainage and foundation stability, but it also enhances the appearance of the site. A level surface is more attractive and necessary for the final structure. Additionally, an uneven surface can create problems with logistics during the construction process.
Types of Grading In Construction
There are various types of grading in construction. Here are six types of construction grading basics that may occur on a site.
Landscape grading involves changing the shape and contours of the land in order to improve irrigation, manage drainage, and create the desired appearance. This process may involve removing topsoil, altering slopes, installing a drainage system, smoothing the soil for planting, or making other significant changes to the land.
Regrading involves altering the elevation of land by grading it. This process, which can also be called a regrade, can be applied to a small or large area and is often used to create a more level surface.
Regrading is sometimes referred to as levelling and may result in nearby slopes becoming steeper and potentially unstable or prone to erosion. Major regrading projects may involve significant changes to the terrain of a city.
Architectural grading involves modifying the shape and elevation of a piece of land to create a suitable foundation and proper drainage for a new building or development, such as a house, residential complex, or commercial property. This may involve removing or filling in certain areas to create a more desirable landscape.
Rough grading is the process of using heavy machinery, such as mini excavators, to shape the land and alter its elevation.
This may involve removing large amounts of soil from certain areas or adding topsoil to create a level surface. Rough grading is typically done early in a grading project to establish the basic layout and contours of the land.
Finished grading is the final step in shaping and elevating the land for a project, whether it be landscaping or construction. This process involves smoothing out the surface by removing any rocks and debris, and preparing the ground for planting or laying gravel. It helps create the desired final shapes and elevations for the project.
In landscaping, the final grade refers to the last layer of sand or topsoil that is applied to the graded surface to support plant growth. Once this step is completed, the area is ready for seeding.
How To Develop A Grading Strategy
To develop a grading strategy, the first step is to gather information about the land through a topographic survey, which provides details about the existing grades, soil composition, and any flooding or seismic activity. Based on this information, a civil engineer will create a grading plan outlining how to reshape the land to drain water and support structures properly.
The specific grading strategy will depend on local laws, the project’s requirements, the land’s shape, and the desired outcome. Some general guidelines for grading include;
Compacting weight-bearing soil to at least 95%, limiting parking lot slopes to 5%, main access drives to 8%, asphalt to a minimum of 1.5%, and concrete areas and curbs to a minimum of .75%.
Stabilized landscapes should not have a slope greater than 2:1, and retaining walls or other stabilizing measures should be used for steep slopes.
Additionally, there should be a minimum of .15m of exposed foundation wall from the top of the foundation to the top of the surrounding grade.
Following these guidelines helps to create a stable, properly drained construction site.