What Happens Before a House Goes Up: Site Prep

Site prep is everything that happens before the foundation: locating utilities, clearing, erosion control, grading so water drains away from the house, and bringing in water, sewer and power. It's about 8% of construction cost on a typical new home, and it decides how your lot handles rain for decades.

What is included in site prep for construction?

On the job sites I worked, grading was where every house started. Here's the usual order:

1. Locate underground utilities. Before any digging, the existing lines get marked.
2. Set up erosion control. Silt fence, construction entrances and other measures that keep soil on the site.
3. Clear the lot. Remove trees, brush and debris where the house, driveway and yard will go.
4. Rough grade. Shape the ground so it's level where the house sits and slopes away from it.
5. Bring in utilities. Water, sewer or septic, power, and sometimes gas, run to the homesite.
6. Prepare for the foundation. Excavate for footings and the slab or crawl space.
7. Final grade, later. After the house is built, the ground gets its finished shape and the yard is stabilized.

Grading is the part that matters most to you long-term. Water should run away from the house on every side.

How much does site prep cost for a house?

It varies with the lot. A flat, open lot costs much less than a sloped or wooded one, or one that needs rock removed or extra fill.

For scale, the National Association of Home Builders' 2024 survey found site work was about 7.6% of total construction costs on the average new home. In a builder's community, much of the bigger site work, like roads and utility lines, happens across the whole neighborhood before individual homes start.

What is the first thing you should do before beginning to excavate a site?

Call 811. In North Carolina, NC811 asks you to contact them at least three working days before you dig. They send your information to the utility companies, which mark their underground lines for free.

That's true for a builder starting a house and for you planting a tree or building a fence later. Hitting a buried line is dangerous and expensive.

Erosion control isn't optional

North Carolina requires an erosion and sedimentation control plan for land-disturbing activity over one acre. The plan has to be approved before work begins and must keep sediment on the site. The state also requires cut and fill slopes to be stabilized within 21 calendar days of finishing a grading phase.

A builder's community is usually covered under a larger plan. You'll see the silt fences and gravel construction entrances while homes are being built.

What it means for you as a buyer

• Look at drainage. Where does water go on this homesite, and on the lots around it?
• Ask about the grade. Is the lot higher or lower than the street and its neighbors?
• Know what's next door. Lots that haven't been graded yet will change.
• Keep the grade. After you move in, don't pile mulch or soil against the foundation or block the swales that move water.

Who's writing this. I sell new homes for D.R. Horton at Collins Ridge in Hillsborough, so I represent the builder, not you. This guide is general education from my years on job sites and in sales. It isn't legal, tax or lending advice, and it doesn't describe any specific home, price or incentive. Check the sources linked below, and talk with your own lender, agent or attorney before you decide.