Garage & Shed Slabs in Grand Rapids, MI

Garage and shed slabs are the concrete floors under detached garages, sheds, workshops and equipment pads. Many older Grand Rapids properties have a detached garage at the back of the lot, often reached by a narrow drive along the side of the house, and many of those floors were poured decades ago with little or no stone base. Over time they crack, sink toward the middle or the door, and let water pool inside. A new shed or a garage rebuild also needs a slab that is level, the right size and strong enough for what will sit on it.

When a garage floor should be replaced

• Large cracks with one side higher than the other
• A floor that slopes the wrong way, so water runs in from the driveway or pools inside
• Heavy scaling where salty slush from the car has dripped for years
• A gap or step at the overhead door where the floor has sunk
• Crumbling edges along the walls

If the floor is solid but has a sunken section, lifting may work. Floors that are broken in many places, or that sit on soft soil, usually need to come out.

Thickness, base and reinforcement

HomeGuide's slab guide lists a two-car garage floor (about 400 to 576 square feet) at $2,400 to $6,900 and says they are typically 4 to 6 inches thick with reinforcement. Shed slabs of 100 to 400 square feet run $600 to $4,800 and are usually about 4 inches thick. We size the slab to the load: a garden shed needs less than a garage that holds a truck, a tractor or a workshop full of heavy tools.

Underneath, we dig out soft or organic soil and compact crushed stone in layers. A garage floor should slope slightly toward the overhead door so water from melting snow on the car drains out instead of pooling. Reinforcement and joints are placed so the floor cracks, if at all, in controlled lines.

Replacing a floor in an existing garage

Replacing the floor of a standing garage takes more care than pouring a new pad. The old concrete is broken out without damaging the walls, the base is rebuilt, and the new floor is placed so it meets the walls and the driveway at the right height. Access can be tight, especially for garages at the back of narrow city lots, which can mean wheelbarrows or a concrete pump instead of a truck chute. We look at this during the estimate because it affects the price.

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Permits and planning

Whether a shed, garage or slab needs a permit depends on its size, use and location, and the rules are different in the City of Grand Rapids, each suburb and each township. Setbacks from property lines and easements also matter. Before we schedule, we check what your city or township requires for the project and let you know.

Curing and first use

HomeGuide's slab guide says a new slab can take foot traffic after 1 to 2 days, vehicles after 1 to 2 weeks, and reaches full cure in 28 to 48 days. If you plan to coat the garage floor with epoxy later, the slab needs to cure fully first. In winter, rinse salty slush off the floor now and then so it does not sit on the concrete.