How to Make a 10-by-10 Concrete Slab

Making a 10-by-10 inch concrete slab is a project that many homeowners complete successfully. It requires physical strength and quite a lot of time, but it is not a complicated job.

Things You'll Need

• Mason's line 20 wood stakes Measuring tape Shovel Line level 40 duplex nails (double-headed nails) 4 2-by-4 inch boards, 10 feet long 3/4 cubic yard gravel Tamper 1.28 cubic yards mixed wet concrete Rakes 12-foot long screeding board Bull float Hand float Polyurethane sheet

Instructions

1. Prepare the site for your concrete slab. Good site preparation is essential for a durable slab, and an improperly prepared site will heave and crack the slab.

   Measure and drive stakes to mark the four corners of the slab. String mason's line around the stakes, check that the slab is square, and mark the ground beneath the line. Remove the line and dig an edging trench about 1 foot wide that extends approximately 3 inches beyond the edge of the slab. Replace the line at the height you want the finished slab to be. Check it with a line level, allowing for a 1-inch grade. Drive four form stakes along each side at 2-foot intervals, making sure the tops of the stakes are slightly below the mason's line. Dig out the entire area inside the mason lines to a depth of at least 5 inches. Remove the soil, and remove any roots larger than 1/2 inch in diameter.

2. Build the form for the slab. This provides a mold for the wet concrete, so the finished form will reproduce its shape exactly. The forms must be strong enough to withstand the weight of the concrete.

   Nail 2-by-4s to the interior of the form stakes with double-headed nails, enclosing the perimeter of the slab. The top edge of the 2-by-4s should run evenly along the height of the mason's line and follow the same grade. Make sure the tops of the 2-by-4s are slightly higher or level with the tops of the stakes; this makes it easier to screed later.

3. Add a gravel base. Concrete needs to be supported by a firm, compacted base that also provides drainage, or it will tilt and break over time.

   Fill in the excavated area with 2 inches of gravel or recycled concrete. Use a tamper to compact the base thoroughly.

4. Pour and screed the wet concrete. Make sure you have plenty of strong helpers, because concrete is heavy, and it can set fast if the weather is hot and dry. Most concrete trucks can distribute the concrete fairly evenly by controlling the rate of the flow and the direction of the chute.

   Rake the concrete into position; when the first 3 feet of concrete is in place, begin screeding while the rest of the concrete is poured. Position the screeding board across the slab at one end, resting on the top of the form. Pull it evenly to the other end of the form while moving it slightly side to side. Screeding consolidates the concrete and makes the surface level.

5. Float the surface. This pushes the aggregate deeper into the concrete and makes the surface smooth.

   Use a bull float to float the surface of the concrete, and a hand float to smooth the edges. If water surfaces while you work, wait a little while and then try again.

6. Cure the concrete. Your concrete slab will be harder and stronger if it cures slowly, so keep it damp and warm for several days. The easiest way to do this is to cover the entire surface with a sheet of polyurethane. If the nights are cold, add a layer of loose straw on top of the plastic. Keep the concrete damp for 3 or 4 days.

7. Remove the plastic and the forms. The concrete will continue to cure slowly for another 28 days.

Tips & Warnings

• Wear heavy rubber boots and work gloves when handling concrete. Rinse your skin with vinegar at the end of the work period to neutralize the alkalinity of the concrete.

• If you get wet concrete on your skin, wash it off promptly.

Resources

• The Portland Cement Association (PCA) has additional information about working with concrete.