Foundations & Shop Slabs Built Square and Level

What a Good Slab Needs Under It

A shop floor that cracks across the middle or sinks at the overhead door usually had a base problem, not a concrete problem. On structural and heavy-duty work we take the time to get the ground right first.

Site prep and compaction

Topsoil and organic material come out entirely; they compress and rot over time. Fill goes back in as gravel, compacted in lifts rather than dumped and leveled. On a big shop pad the difference between compacted and uncompacted fill shows up as a cracked floor within a few winters.

Vapor barrier and insulation

Under a heated shop or a garage you plan to finish, a polyethylene vapor retarder keeps ground moisture from wicking up through the slab. If you’re considering in-floor radiant heat, rigid insulation and the PEX tubing go down before the steel, so decide early. It can’t be added later.

Reinforcement and thickness

Shop floors that see tractors, loaders or loaded trailers get more thickness and a tied rebar grid held up on chairs. We thicken the slab at the perimeter and under the overhead doors where wheels concentrate the load, and we add steel where posts or a future lift will sit.

Joints on big floors

Large slabs shrink as they cure, and they will crack somewhere. Saw-cut joints laid out in a grid give that crack a place to go. We cut them as soon as the concrete can take the saw without raveling, usually within hours of the pour, because waiting until the next day is often too late.