Site Excavation in the Catskills & Hudson Valley

How a foundation dig actually goes

It starts with stakes. Your surveyor or builder marks the corners and sets a height for the bottom of the footing, and Justin digs to that, plus a couple of feet of working room outside the walls so the forms and waterproofing can go in. Before the bucket goes deep, he gets underground utilities located and marked. The topsoil comes off first and goes in its own pile.

Footings have to sit below frost depth, which is about 4 feet in most of this area, and they have to bear on undisturbed soil or rock, not loose fill. If the bottom of the hole turns soft from rain or groundwater, the soft material comes out and gets replaced with stone before anyone pours. Once the walls are up and cured, the hole is backfilled in lifts, with drainage stone and footing drains where the plan calls for them, and the ground is shaped to carry water away from the house.

Smaller jobs follow the same logic. For a covered porch, deck or addition, it's usually a set of pier holes or a short footing trench, dug to the same depth and cleaned out so the forms or precast piers drop in plumb.

What drives the cost and schedule of site excavation

The ground decides more of the price than the size of the house does. Two lots a mile apart can be completely different jobs. The main factors:

• Rock. In the mountain towns, bedrock can show up a few feet down, and the glacial till above it is packed with stones and boulders. Ledge in the footprint means slow digging, hammering, or a change to the design. See rock and boulder removal.
• Access and slope. A steep wooded lot with a narrow way in takes more machine moves than an open field, and the concrete trucks need a way in too.
• Water. A high water table, or clay that holds water like much of the ground near the Hudson, means pumping and extra stone under the footings.
• Spoil. Every yard that comes out of the hole has to go somewhere. Room to stockpile it on site is far cheaper than trucking it away.

What should you have ready before the excavator shows up?

Have the house or addition staked with a height benchmark set, your building permit in hand if the town requires one, and a clear plan for where the topsoil and spoil piles will go. Point out anything buried that isn't a public utility, like a well line, septic pipe or propane line, and make sure trucks can reach the hole.

Private lines matter because a utility locate only marks the public ones. If you know where your well line or old septic pipes run, tell Justin before the dig. If trees stand in the footprint or the driveway path, the lot needs land clearing first, and stumps have to come out completely, roots and all, anywhere the house or driveway will sit.

Mistakes that cost you later

Most foundation problems start in the hole, long before anyone sees a crack. These are the ones worth avoiding:

• Pouring footings on fill, or on mud that sat under water overnight. It settles, and the cracks show up a year or two later.
• Mixing topsoil into the backfill. Keep it separate and spread it last. Buying it back is expensive.
• Backfilling before the walls are cured and braced. Heavy, wet backfill can push a green wall in.
• Throwing stumps, big boulders or construction debris against the foundation. They rot, settle or point-load the wall.
• Leaving the yard flat or pitched toward the house. Water will find the basement.

Don't pour a slab or patio on fill that hasn't been compacted in lifts, either. When the digging is done, grading and landscape prep sets the final slope, and drainage work handles any water the grading alone can't.