ENGINEERED DEMOLITION INC

Demolition contractors take down houses, garages, commercial buildings and foundations, then sort and haul what is left. The teardown itself is the fast part; most of the schedule is the paperwork that has to happen first. Gas, electric and water are disconnected and capped at the main, an asbestos survey is completed by a licensed inspector and any friable material is abated before the excavator swings, and the demolition permit is posted. A residential house typically comes down in one to two days with a 30 to 40 ton excavator; hauling and backfilling the hole can take a few more. Selective demolition, such as removing a wing or gutting an interior for a remodel, is priced by labor hours because it is done with hand tools and small machines around what stays.

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.

Concrete cutting and removal contractors saw, drill, break and haul concrete on everything from a cracked patio to a doorway through a foundation wall. The tools are specialized: walk-behind slab saws with diamond blades for flat cuts, track-mounted wall saws for straight openings, core drills for round penetrations for pipe and conduit, and hydraulic breakers or robotic demolition machines for bulk removal. Wet cutting controls silica dust, which OSHA regulates tightly, but produces slurry that has to be contained and disposed of rather than washed into a storm drain. Because a saw cannot see rebar, post-tension cables, conduit or radiant tubing inside the slab, a GPR scan before cutting is standard practice on any structural or unknown concrete, and cutting a post-tension slab without one can be dangerous.