For Homeowner

What to Look For on Site Grading Plans

Dec 16, 2019
Design Everest

If you’ve ever laid eyes on a site grading plan and felt confused by the convolution of lines, arrows, and numbers, you’re probably not alone. These drawings are loaded with information about your building’s site, its vicinity, as well as the proposed work. A good grading design will effectively manage drainage, ensure the right depth for your building’s foundation, and account for your preferred landscaping features.

A quality site grading plan will help you avoid unnecessary delays during permitting and enable the earthworks contractor to come up with an accurate estimate. The features below help civil engineers communicate their design requirements to city building officials and the contractors working on your project.

Vicinity map and North arrow

Tucked in the corner of a site plan, this smaller drawing shows the site’s location in the context of the neighborhood, while the North arrow shows the site’s orientation. Planning and building departments will use this map to establish the site’s location, and earthworks contractors may also find it useful in planning site access.

Survey marker location

A benchmark elevation marker is the known reference point based on which the site was surveyed. Typically, surveyors use markers placed by the National Geodetic Survey - small brass discs that depict the elevation above mean sea level of the point to which they’re permanently affixed. A good site grading plan will list the location of the marker based on which the site was surveyed.

Lot size and coverage

A quality site grading plan should show the total lot area, as well as the area of the proposed building and any accessory structures. The drawing should also include the lot coverage percentage calculation:

Lot Coverage = building area / lot area x 100

Most jurisdictions have lot coverage restrictions in their zoning codes, and this calculation allows planning officials to see whether the proposed building adheres to the development standards.

Earthwork estimate - cut/fill

The engineer responsible for producing the grading plan should show their projected cut and fill quantities. These are shown in cubic yards and serve as a benchmark for the earthworks contractor, who also quantifies the amount of soil displaced during grading.

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Sections

In architecture and structural engineering, a section drawing shows the hidden areas of an element by presenting a view of the element as if it’s been dissected along an imaginary plane. In a grading plan, sections are typically used to show the proposed cuts, fills, driveways, and building pads. Together with the plan, these sections help building officials and earthworks contractors visualize the scope of work.

Contour lines

A contour is an imaginary line that connects points at the same elevation on a site. Imagine the edge of the water in a perfectly still lake - the line it traces around the lake is a contour line. On site grading plans, contour lines are typically spaced at 1-foot vertical intervals, with hatched lines representing existing elevations and solid lines showing proposed ones.

Spot elevations - existing grade, finished grade

Spot elevations show the proposed and existing elevations of points on the site plan. Typically, they’re used to depict points which are higher or lower than their surroundings, as well as points critical for construction, such as the entrance and corners of a building, top, and bottom of retaining walls, as well as the elevations of various drainage features.

Drainage flow direction

Drainage flow is represented with an arrow pointing in the direction of the outflow. This important marker helps city officials and earthworks contractors understand how the site’s grading design incorporates drainage.

Property line

A property line is the demarcation of the legal boundary between the lot in question and the adjoining properties and/or public land. The property line helps city officials verify the lot dimensions, setbacks, and lot coverage. Earthworks contractors will use this information to devise their site access plan.

Setbacks from each face of the building

Setbacks are the clearances between a lot’s property line and the exterior wall of the building or its accessory structures. Most jurisdictions have minimum front, rear, and side setbacks outlined in their zoning codes, and your local planning department will verify that your building’s setbacks meet these standards before giving their approval.

Easement lines and utilities

An easement is a right to cross or make use of a portion of private property. Most easements are granted to utility companies who have no choice but to locate their services below or above private lots. In most cases, you are not allowed to disturb or obstruct access to easements on your property. If your lot has a public utility easement, an easement line will show it on the site plan. Likewise, public utilities adjacent to your property, as well as proposed points of connection, will also be shown on the site plan.

Finished Floor Elevation and the Base Flood Elevation

In California, homes built on a floodplain must have their lowest floor above the Base Flood Elevation (BFE) level. If your lot is on a floodplain, chances are that building officials will pay close attention to the elevation of the home’s finished floor. This information is typically included on site grading plans to certify that the proposed home’s floor will be constructed above the BFE level. It will also help the earthworks contractor to estimate the cut and fill quantities.

Grading features

It is crucial for any project to have proper drainage in order to direct the flow of water away from the building and neighbouring properties. To facilitate this, features such as berms, swales, ridgelines, retaining walls, and rip raps are often used in grading design when the existing topography does not allow adequate drainage. On a site grading plan, these features show the project’s approach to drainage and guide the earthworks contractor.

Apart from drainage, a grading plan should also depict landscaping features such as walkways, ponds, gardens, swimming pools, or any other items you may use to customize the site around your home.

What we can do for your site

If your project involves grading, Design Everest can help. Our team of civil engineers can devise a grading strategy that drains rainwater away from your building and the adjoining properties while letting you incorporate landscaping features that you find aesthetically pleasing. Call us at (877) 704-5727 or email us at info@designeverest.com to discuss your project and receive a quote today.

Sources:
[1] https://s3.amazonaws.com/suncam/docs/188.pdf?1536486317/
[2] http://buildingincalifornia.com/flood-zones/
[3] https://designeverest.com/services/civil-engineering/#site-grading

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