Garage floors, sheds, pads and additions
Concrete Slabs in Wilmington, DE
Flat, solid slabs sized and reinforced for what will sit on them.
- Free on-site estimates with measurements
- Itemized written quote before any work starts
- Air-entrained mixes and planned control joints for Delaware winters
Slabs Sized for the Load They Carry
Concrete slabs are the plain, working concrete under garages, sheds, AC units, generators, parking spaces and home additions. A good slab is flat where it should be flat, pitched where water needs to drain, and thick and reinforced enough for what sits on it. In and around Wilmington we pour slabs for detached garages behind older homes, replacement floors in garages where the original concrete has cracked and sunk, and new pads for sheds and equipment in suburban backyards.
What goes into a slab
The ground under a slab matters as much as the concrete. We remove topsoil and organic material, compact the subgrade and place a stone base. For interior slabs and garage floors, a vapor barrier under the concrete helps keep moisture from wicking up. Forms set the size and the finished height. HomeGuide's slab guide notes most slabs are 4 to 6 inches thick, and that larger slabs may need rebar or wire mesh. We choose thickness and reinforcement for the load: a shed pad is a different job from a garage floor that carries a car or a pad for a heavy generator.
Garage floors
Where an older house has a detached garage out back, its floor often cracks, sink toward one corner, or break up where water runs in under the door. Replacing a garage floor means breaking out the old slab, correcting the base, and pouring a new reinforced slab pitched toward the door. Garage floors see salt from cars in winter, so an air-entrained mix and a sealer help them last. HomeGuide puts a two-car garage floor of 400 to 576 square feet at about $2,400 to $6,900.
Pads and small slabs
- Shed slabs: level, square and slightly above grade so water does not collect at the base of the shed.
- AC and generator pads: small slabs set level so equipment runs right and stays out of mud and standing water.
- Parking pads: off-street parking behind rowhomes or beside a house, thick enough for vehicles and pitched toward the alley or yard.
- Trash and utility pads: a clean, level spot for bins, firewood or a dog run.
Slabs for additions, sunrooms and porches
An addition or sunroom slab ties into the house and usually sits on footings or a thickened edge that reaches below frost depth. New Castle County's footing checklist sets the base of footings at 32 inches below finished grade. These slabs are typically part of a permitted building project, so we work to the plans and inspection schedule for the job.
Working on sloped and low ground
Wilmington sits on the fall line. West of Market Street the land is rocky and hilly, and east of it the ground is flat, low and in places marshy. On a slope, a slab may need a thickened edge or a short retaining form on the low side. On low, wet ground, a deeper stone base and careful grading keep water from softening the soil under the concrete. We look at this during the estimate.
Curing a slab right
Concrete gains strength slowly. We keep new slabs moist or covered while they cure, protect them from frost in cold weather, and tell you when you can load them. Garage floors usually wait about a week before parking; heavy equipment waits longer.
What This Covers
Slab work covers the ground prep, the concrete and the details that make a slab last.
Garage floor replacement
Old floors broken out and replaced with a reinforced slab pitched to the door.
Shed and outbuilding slabs
Level pads sized to the building, set slightly above grade.
AC, generator and equipment pads
Small, level pads for outdoor equipment.
Parking pads
Off-street parking slabs off alleys, driveways or the street.
Addition and porch slabs
Slabs with footings or thickened edges for building projects.
Vapor barrier and reinforcement
Moisture barrier, rebar or mesh as the slab requires.
Typical Concrete Slab Costs
| Slab | Published range |
|---|---|
| 4 in slab, per sq ft | $6 to $8 |
| 6 in slab, per sq ft | $8 to $10 |
| 10 x 10 ft slab | $600 to $1,200 |
| 12 x 12 ft slab | $860 to $1,700 |
| 20 x 20 ft slab | $2,400 to $4,800 |
| Two-car garage floor (400 to 576 sq ft) | $2,400 to $6,900 |
| Shed slab (100 to 400 sq ft) | $600 to $4,800 |
| Gravel base, per sq ft | $1 to $3 |
National ranges from HomeGuide's concrete slab cost guide. Wilmington-area prices can differ, and demolition, access, thickness and reinforcement all change the total. Your written estimate is the price.
How It Works
1. Size the slab
We measure, ask what the slab will carry and check grade and drainage.
2. Prepare the ground
Excavation, compacted subgrade, stone base and vapor barrier where needed.
3. Form, reinforce and pour
Forms are set level or pitched, reinforcement placed and the concrete poured and finished.
4. Cure and load
The slab is kept moist while it cures, and we tell you when it can take weight.
Concrete Slabs Questions
How much does a concrete slab cost?
HomeGuide's national range is about $6 to $8 per square foot for a 4 inch slab and $8 to $10 for 6 inches. A 10 by 10 foot slab runs about $600 to $1,200 and a 20 by 20 foot slab about $2,400 to $4,800.
How thick should a shed slab be?
About 4 inches is typical for a shed. Heavier buildings, workshops or anything with a vehicle inside need a thicker, reinforced slab.
Does a slab need rebar or mesh?
Small pads often do not. Larger slabs, garage floors and slabs that carry heavy loads usually get rebar or wire mesh. We decide based on size, soil and load.
Can you replace an old garage floor without tearing down the garage?
Usually, yes. We break out the old floor inside the walls, prepare the base and pour a new slab. Access and the condition of the garage walls are part of the estimate.
Do I need a permit for a slab?
Simple pads often do not, but slabs for additions, garages and porches are usually part of a permitted project. We check what your city or county requires.
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Get a Concrete Slabs Estimate
Free slab estimates in Wilmington and northern New Castle County.