Before Anything Moves: Plans, Stakes, Locates
The excavator cannot start from a lot line and a floor plan. Three things have to exist first:
- A site plan with elevations. The foundation plan gives the footing elevation and the top-of-wall elevation. The site plan says where the house sits on the lot, where the driveway goes, and how the finished grade falls away from the house. If your plans say "finished floor = 100.00" with no benchmark tied to the real world, the surveyor has to set one before the dig.
- Survey stakes. A surveyor sets corner pins for the house and usually offset stakes so the corners can be re-established after the dig wipes them out. Do not let anyone talk you into digging off a tape measure from the property pin.
- An 811 locate and a building permit. Even on a bare lot, there can be a gas main, a water main, or a fiber line along the road frontage. The locate is free and takes three working days. The building permit from Jefferson County or the municipality has to be issued before the dig starts, and the excavation itself is often the first inspection point. Our excavation permit guide walks through who issues what.
Step 1: Clearing and Access
On a wooded Jefferson County lot this is a real job on its own. Trees inside the house footprint plus a working margin come down, stumps are pulled or ground, and the brush is hauled or burned where the county allows it. At the same time the excavator cuts a construction entrance: a rock pad where the driveway will go, so concrete trucks and lumber deliveries do not sink into a muddy lot in March.
Clearing is also when the silt fence goes in. Jefferson County and most municipalities require erosion control before disturbance on a lot over a certain size, and inspectors do look. See erosion control for Jefferson County lots for what is typically required.
Timeline: Half a day for a cleared subdivision lot. One to three days for a wooded acreage lot, longer if there is a lot of stump and debris haul-out.
Step 2: Stripping Topsoil
The top 4 to 8 inches of the house footprint and the areas that will be driveway and patio is organic topsoil. It cannot stay under anything structural because it settles as the organics break down, so it gets stripped and stockpiled somewhere it will not be in the way for two months. It comes back at the end for the lawn. Stripping it into a separate pile, rather than mixing it with the basement spoil, is the difference between having usable topsoil at the end and having to buy 40 tons of it.
Step 3: The Basement or Foundation Dig
This is the step most people picture. The excavator cuts the footprint down to the footing elevation from the plans, plus 2 to 3 feet of overdig around the perimeter so the foundation crew has room to set forms and the waterproofing crew can work the outside of the wall. A ramp is left on one side so equipment can get in and out.
Two things decide how this day goes in Jefferson County:
- Rock. Much of the county sits on limestone, and a shelf of it inside the dig depth is common on the hills between Festus, Hillsboro, and Arnold. When the bucket stops, a hydraulic hammer goes on the machine and the day becomes a hammering day. Good excavators will tell you the moment they hit it, because it changes the invoice.
- Where the dirt goes. A basement produces a lot of spoil, on the order of 500 to 800 cubic yards for an average house. Some of it is needed back as backfill. On a big lot the rest gets stockpiled and worked into the final grade. On a tight subdivision lot there is nowhere to put it and it leaves on trucks as it comes out, which is a cost worth asking about up front.
Slab-on-grade and crawlspace houses skip the deep dig but still need footings trenched to frost depth, 30 to 36 inches in this part of Missouri, and the interior stripped and leveled for the slab base.
We cover this step in more depth on the basement excavation service page, including what to have ready before the machine shows up.
Timeline: One to two days for a residential basement in normal soil. Add a day for rock or for hauling all spoil off a tight lot.
Step 4: Footings, Walls, and Waiting
The dirt contractor leaves. The foundation contractor forms and pours footings, the county inspects, walls are formed and poured or blocks are laid, and the walls cure. Then the waterproofing crew coats the outside and installs drain tile at the footing. That is typically two to four weeks during which the hole sits open. If it rains hard in that window, water in the hole is normal; it should be pumped before backfill, not backfilled over.
Step 5: Utilities In
Before the hole is closed is the time to run everything that needs to enter the house below grade: the water service, the sewer lateral or septic line, and often the electric and gas conduits. Each one is a trench from the house to the road or the tap, at a depth the utility specifies. On a Jefferson County lot that can mean a couple hundred feet of trench per utility. The utility trenching guide covers depths and sequencing, and new water line installation covers the water service specifically.
Where the trench crosses the road frontage or an existing utility corridor, hydro excavation is used to expose the existing lines before a bucket goes near them. That is not optional near a gas main.
Step 6: Backfill and Rough Grade
Once waterproofing and drain tile are inspected, the excavator comes back. Clean stone goes over the drain tile, then the overdig is backfilled in lifts, a foot or so at a time, so the wall is loaded evenly and the fill does not settle into a trench along the house later. Using the subsoil from the dig is normal; using the topsoil pile is not.
Rough grade follows: the lot is shaped so water runs away from the house on every side, the driveway subgrade is cut, and the swales that carry runoff to the ditch or the street are established. The house sits at this grade through framing and finishing.
Timeline: One day for backfill and rough grade on most lots, once the foundation crew releases it.
Step 7: Final Grade, Driveway Base, and Topsoil
Months later, after siding and gutters are on and the heavy trucks are done, the last visit spreads the stockpiled topsoil, cuts the final swales, and lays the driveway base. That last part is usually 4 to 6 inches of crusher run compacted over the subgrade, whether the driveway will be gravel, asphalt, or concrete. The grading page and our land grading cost guide cover what finish grade involves and what it runs.
What Drives the Cost
Excavation for a new house is priced per visit and per task, not as one number, and the spread between an easy lot and a hard one is wide. The variables that move it most:
| Variable | Cheaper end | Expensive end |
|---|---|---|
| Lot condition | Cleared, flat subdivision lot | Wooded, sloped acreage with stumps to haul |
| Foundation type | Slab or crawlspace, footings only | Full basement with walkout, deep cut on the high side |
| Rock | None inside dig depth | Limestone shelf at 5 ft, hammer time billed hourly |
| Spoil | Stockpiled and reused on site | Every load hauled off a tight lot, clean fill brought back |
| Utility runs | Short runs, sewer at the lot line | Long runs, road bore, septic field |
| Access | Machines drive on from the street | Lowboy required, entrance pad, mud season |
For the ranges we actually see on residential jobs, the Missouri excavation cost guide breaks it out by task. The short version: on an easy lot the entire dirt scope is a modest share of the build; on a rocky, wooded, sloped lot it can approach what the foundation itself costs, and it is the number most first-time builders underestimate.
How to Get an Accurate Excavation Bid
- Send the site plan and foundation plan, not just the address. The elevations are what we price from.
- Say whether the lot is cleared and whether you want spoil stockpiled or hauled.
- Ask the bid to break out the visits: clearing, dig, utilities, backfill, final grade. A single lump sum hides where the risk is.
- Ask how rock is handled and at what rate. Anyone who says "we never hit rock" in Jefferson County has not dug here much.
- Confirm who calls in the 811 locate and who pulls the permit. It is usually the general contractor, but on an owner-built house it is you.