How to Excavate for a Concrete Slab

By eHow Home & Garden Editor

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You have a nice spot in the yard for a patio, or want to build a garage or storage shed. No matter how big or small the project, the first step is to excavate for a concrete slab. If you don't mind some hard work, you can excavate yourself. Once you plan and measure everything, grab a shovel and start excavating.

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Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

Measuring tape
Stakes
String
Shovel
2-by-10 inch boards
Gravel
Tamper
Level
Steel bars, 1/2-inch thick

Step1

Check your local ordinances for building outdoor structures. You may be limited as far as size, placement or type of structure. Make sure you are within ordnance laws before purchasing materials.

Step2

Measure out the area for the concrete slab. Shape by placing stakes in the four corners of the area and forming square with string. Check area for square by measuring from one corner diagonally to the other corner. Adjust position of stakes, if necessary.

Step3

Shovel down 10 inches—6 inches for gravel and 4 inches for thickness of the concrete slab. Remove rocks and large roots to leave the bottom of the excavated site as smooth as possible. For water runoff, pitch ground 1/4 inch for every foot. Slope away from the house or other outdoor structures.

Step4

Use 2-by-10 inch boards to build a form, which holds the gravel and concrete slab in place. Pour in 6 inches of gravel, and tamp down. Smooth out gravel to make a level surface, allowing enough space for the concrete slab to be level with top of the area you want to excavate.

Step5

Install 1/2-inch steel bars to form a reinforcing grid for the concrete. You can lay large flat rocks beneath the middle of the grid for additional support.

Step6

Place bars every 2 feet from the sides, back and front of the excavated area. Tie where the bars intersect with wiring.