Command Site Contractors

Concrete flatwork covers everything flat and horizontal: garage and shop slabs, patios, sidewalks, equipment pads and aprons. Most of what determines whether a slab lasts happens before the truck arrives. The subgrade is compacted, a gravel base of about four inches is placed and compacted, forms are set to grade with slope away from the building, and reinforcement, typically wire mesh or #3 or #4 rebar on chairs, is placed. Residential slabs are usually four inches thick and poured at 3,000 to 4,000 psi; anything that will see trucks or equipment goes to five or six inches. Control joints are cut at intervals of roughly two to three times the slab thickness in feet, so about every eight to twelve feet on a four-inch slab, because concrete will crack somewhere and joints tell it where. Concrete needs about seven days before foot traffic and twenty-eight to reach design strength.

Erosion and sediment control keeps disturbed soil on the site and out of storm drains, ditches and neighboring property while construction is under way and until vegetation is established. Under the federal Clean Water Act, any project that disturbs one acre or more needs coverage under a construction stormwater permit and a written plan, commonly called a SWPPP, and many cities set lower thresholds. The physical work is simple and unglamorous: silt fence trenched in along the downhill perimeter, a stone construction entrance so trucks do not track mud onto the road, protection around every inlet, check dams in ditches, and erosion control blanket or hydroseed on slopes. What most owners underestimate is the maintenance: controls have to be inspected after every rain of a quarter inch or more and repaired, and inspectors write violations for torn fence and full silt traps, not for missing paperwork.

Excavation contractors dig and move earth for foundations, basements, utilities, pools and site cuts. Most residential jobs run on a mini or mid-size excavator paired with a skid steer and a dump truck; larger cuts bring in a dozer or scraper. The price depends less on the size of the hole than on what is in the ground: clay, ledge rock, high groundwater and buried utilities all slow the machine down and change the hauling math. Before the bucket touches dirt the site needs an 811 utility locate, and any trench deeper than five feet needs a protective system under OSHA rules.

Foundation contractors build the part of the structure that carries everything above it into the ground: spread footings below frost depth, stem walls or basement walls, monolithic and slab-on-grade foundations, and pier or grade beam systems where soils are poor. The work follows the stamped plans and the geotechnical report, and it is inspected at fixed points, usually the open footing trench with rebar in place before the pour, then again before the slab and before backfill. Frost depth sets the footing bottom, from about twelve inches in the Gulf states to four feet or more across the northern tier. Waterproofing or dampproofing, a footing drain and free-draining backfill are what keep a basement dry, and they are cheapest to do right while the wall is still exposed.

Grading is the shaping of ground to a designed elevation and slope. Rough grading moves the bulk of the earth to bring a site close to plan; finish grading dials in the last few inches so a pad is level and a yard sheds water. The number that matters is fall: building codes call for the ground to drop at least six inches in the first ten feet away from a foundation, and a lawn or gravel area needs roughly a two percent slope to drain. Crews do this with a dozer, a skid steer with a grading bar, or a motor grader on larger lots, checked against a laser or GPS grade stake rather than by eye.