Pouring A Concrete Slab-A DIY Project

Concrete is probably one of the greatest inventions ever invented by man or was it woman? The Romans used it to expand their empire by building some of the greatest aqueducts ever known to man. If fact, it was the Roman invention of underwater concrete that allowed them to build the first concrete piers ever known. This achievement alone allowed them to create or expand harbors in locations that until that time were useless as such. Yet, even today pouring concrete is considered a difficult, only to be sourced out project that in truth any homeowner can do with a little preparation and skill.

The best concrete project for any homeowner to tackle is that of a patio or short walkway. The advantage of these two choices is that they are both large enough for a concrete truck, but small enough for a crew of two to tackle.

In any concrete project, there are some basic tools that everyone needs in order to complete a good professional looking project.

Trowels

Level

L-square

Chalk Line

Tape Measure

Brushes

Float

Wheel Barrow

Shovel

Framing / Layout

Whether constructing a walkway or a patio, the first thing you will need to do is use mason string and a few wooden stakes to draw the outline of your project. After you have determined the physical dimensions of your project the next thing is to dig out the area where you plan to pour your concrete. In the case of a patio that is 12 x 12, you will need to remove all of the sod and loose vegetation to a depth of at least 5 inches and no more than 6 inches. Most walkways and patios will use a concrete thickness of 4 inches; so digging to a depth of 5-6 inches will allow you to place a layer of patio sand as a base for your project.

Next, using the mason string as a guide you will need to begin creating your wooden form for the patio or walkway. The best method for doing so is to use standard pine 2x4’s with 1x4 stakes every 3 feet to hold it in place. Traditionally, nails have been used to hold the stakes to the frames, but I generally find screws or even staples and a staple gun to be the best and easiest method for nailing the stakes to the 2x4 form. As you build your form, be sure to check it for level as you go. Level you say? Well not really, in the case of a patio or walkway, you will want it to slant away from the house or you may find that when it rains you have water streaming into your home and not into the yard. So first level your frame with a slight slope downwards away from the house (about 1” per 10 feet) and then check it for square with a L-square.

After you have confirmed that all is level, (with a slight slope) and square, it is time to add the paver sand to the form. I generally like to use paver sand that is compacted by a tamper, (rent this at a rent-a-tool place), so that I have a solid base for my concrete. If you don’t want the extra expense, then just rent a tamper to pack down the soil, but your original digging should be no more than 4” overall. You don’t want to use more concrete than necessary as it can add up.

Note: if you live in a frost area, you will need to check local codes, as many will require a gravel bed with a perimeter ditch.

Rebar

Once your bed is prepared, it is always a good idea to use wire mesh or rebar in your concrete. Have you ever wondered how concrete can crack when it is such a strong material? Well as it happens, concrete has a great compression factor, but really sucks when it comes to tensile strength. What does that mean? Concrete can stand up to squeezing real well, but if you push, it will crack without rebar to give it that little bit of extra strength, kind of like a bone and tendons do for our legs. The bones will allow compression, but the tendons will help keep our knees from snapping when we are hit from the side. So the bottom line, your patio or walkway will need either rebar or wire mesh to help keep it from cracking. I generally prefer 5/8” rebar, but most will use wire mesh.

So, install your rebar with the bars creating a checkerboard pattern. Wire the rebar each time two pieces of rebar touch each other and you will need to support the rebar off the ground so that when you pour your concrete the rebar will be inside and not under the concrete. Generally, using a rock will work great, just don’t use anything organic as it will rot and leave a gap that may result in a hole later on.

Concrete

Now when it comes to concrete, not all concrete are made the same, so ask around and use a reputable service. You will note that I am suggesting using a concrete truck service, for if you have never mixed and poured concrete yourself, you have no idea just how hard it is to do. So save your back and hire someone to mix and deliver the concrete, as you will find the price difference really is not that much at all.

Pouring / Finishing

Pouring concrete really is not that difficult and if you watched any DIY shows, you know that getting an early start is critical to doing a good job. For having your concrete delivered an hour before sunset will leave you with no time at all to level and finish before the sun sets, so do yourself a favor and start as early as you possibly can.

Generally you can back the concrete truck right up to your project and use the chute on the truck to pour your concrete directly into your forms. If this is not the case, be sure to have a few extra friends and wheelbarrows on hand to carry the concrete and dump it into your forms. As they pour the concrete, use a shovel to tamp out the air pockets that form. Once you have enough concrete in your form, use a 2x4 to strike or screed off the excess concrete. Just place the 2x4 on the two edges of the form and using a back and forth motion, move from one end of the form to the other. Use a shovel full of concrete to fill in any low spots. Make sure that you strike or screed the form at least twice to make sure you have no unevenness in the concrete.

Note: this will require to people two perform this operation properly.

Finishing

Use a float to smooth the concrete as it dries. The float will push the aggregate, (rocks); down below the surface giving you a smooth even look to your concrete. If you don’t want to have a smooth surface, use a broom to sweep the concrete just before it is done to give it a rough textured feel. As the concrete begins to dry, you will also want to use a edging trowel to give the outer edges a rounding that will help prevent cracks and chipping.

Note: there are a variety of finishes available for concrete, so do a little homework and see what is best for your project.

Enjoy!