Whether it’s for a shed, stair landing, dog kennel or hot tub, a small concrete pad is an easy and inexpensive home improvement project. Turn that section of matted grass into a functional and practical surface with a little elbow grease and this know-how.
First, a disclosure: This guide isn’t meant to be a concrete-project encyclopedia. But it will set you up to complete a small weekend undertaking for any pad measuring 100 square feet or less.
Plan, Layout and Dig
Determine the size of the pad you need. Take into consideration any extra space required around a hot tub for steps or in front of a shed door to keep grass and dirt out. Mark off the area with stakes or spray paint. It doesn’t have to be perfect, but ensure the area you mark is square. Now dig.
Ultimately, for a pad to sit 2 inches above ground level, you’ll want to excavate down roughly 6 inches. And make sure to remove enough soil outside of your marks to accommodate formwork—4 inches should do the trick.
Prepare the Subgrade
We know, we know . . . it’s a small project. But regardless of size, properly preparing the base material improves the lifespan of your concrete. Use a bow rake to level the dirt and remove any large rocks or debris. Dampen the soil with water. Now, use a hand tamper to compact the base. Go ahead, take all your frustrations out on that dirt. “Beat the devil out of it,” as Bob Ross would say.
Next put sand, gravel or crushed stone into the hole. It adds to the strength of the concrete and acts as a capillary break, stripping groundwater’s ability to wick up through the pad like a sponge. If you’ve dug down 6 inches and want the pad to finish 2 inches above the ground, you’ll need to add 4 inches of subgrade material. This will allow for a 4-inch pad, a typical and adequate thickness for most home-based uses.
For smaller pads, you can often prefabricate the form using 2x4s and lay it into the prepared area. Make sure you have nice, straight lumber. Cut your boards long enough so that the inside measurement of the form is the desired size of the pad—which will typically mean adding an inch and a half to each side. Now, screw the boards together at each corner.
Place the form into the prepared site and drive stakes 8 inches into the ground every 2 to 3 feet along the outside edges of the boards. After making sure the form is square and level, and accounting for drainage, attach the form to the stakes with screws or nails from the outside so that you can remove them after the concrete is poured. You can even make the stakes yourself out of spare lumber. The idea is simply to ensure the form is supported enough as to not blow out under the weight of wet concrete. Pro tip: Make sure the stakes are flush, or just below, the top of the form to simplify leveling, or screeding, the wet concrete. To avoid three common concrete forming mistakes, check out our other blog.
Here’s where all your hard work pays off . . . or just begins. Mix the concrete according to the manufacturer’s instructions either by hand in a wheelbarrow or with the help of a cement mixer. Pour half of the concrete in the form and roughly level. Now, put in concrete-reinforcing steel mesh cut just less than the size of the form. Do you really need reinforcing material? Does a Snickers really need caramel? Does a chocolate chip cookie need chocolate chips?
While opinions about using reinforcing steel vary online, the fact is that concrete has low tensile strength. To offset this, it’s essential to add a material with high tensile strength, a.k.a. steel. Concrete will crack. That’s inevitable. But using reinforcing steel mesh will help to keep the cracks smaller, allow the pad to carry more weight and increase its lifespan. For larger pads, a stronger reinforcement option is a lattice-work of steel rebar.
After reinforcing material is placed halfway through the concrete, finish pouring to the top of the forms.
Level (screed) the concrete in a back-and-forth sawing motion with a 2×4 cut plenty long enough to span the form. This is where ensuring the stakes are lower than the tops of the form will pay off. Continue working the surface until all excess concrete is removed and there are no voids. If there are low spots or voids, add concrete to those areas and relevel.
Water will appear after a short time, creating a sheen on the surface. Wait until this water disappears back into the concrete before edging, jointing and hand-floating. Aside from waiting for the gloss to vanish, pressing your thumb into the concrete near the perimeter will give you an idea of when it’s ready for the next step. When pushing hard only leaves a 1/4-inch deep impression, it’s ready. Note: Larger pads should be smoothed with a bull float immediately following the screeding.
Use an edging tool around the form to create a smooth, round edge. If the pad is large enough, use a hand groover and a straight edge to create straight joints about every 4 feet. Use a hand float in sweeping arcs to compact and smooth the surface. When it comes to choosing a hand float, you have to decide between magnesium or aluminum, which is a can of worms in itself. It may be worth a conversation with a professional or experienced DIYer to better understand what float may be best to use for your application.
After the concrete is partially hardened—this time varies on the mix and weather conditions—use a trowel to complete a smooth finish and lightly broom for a non-slip surface. If you’re trying to smooth with a trowel or rough with a broom and the surface is not forgiving, add a little bit of water to the top. That should do the trick.
As you work on your project, use rubber gloves, a long-sleeve shirt and safety glasses. Concrete can, and will, cause chemical burns. Safety first!
You’re undoubtedly excited to use your new landing or take a soak in the hot tub, especially after all that work! But removing the form too early can ruin your project. Instead, relax a bit. Leave everything alone for at least two days—and maybe longer, depending on the weather. Removing forms too early can cause concrete to sag, crack or collapse. But, even after the form is removed, it’s important to stay off fresh concrete until it has cured. What’s curing? Read all about the importance of curing in our past blog article.
Intermountain Concrete Specialties: Here to Help
Completing your own concrete project is rewarding. Done correctly, you’ll be left with a finished product that will withstand years of use. With more than 69 years of experience, Intermountain Concrete Specialties can help with your DIY concrete project needs. We rent specialty concrete equipment and forms. We offer all the hand tools needed for a beautiful project. And we have the expertise and knowledge to help with any concrete undertaking—big or small. Contact us at one of our seven locations from St. George to Idaho Falls today to see how we can help.