How To Build Concrete Patios

By David Beaulieu

Landscaping Expert, about.com

Learning how to build a concrete patio could be a great boon for your yard. Properly made, these structures are durable and, with some landscaping imagination, can complement a garden, a house entrance, or other area of your landscape. Some prefer this material as a base for bricks, but, with some creativity, concrete can be reasonably attractive in its own right.

Although there is hard work involved, this is a suitable project for beginners to tackle, because the concepts behind it (once explained thoroughly) are simple enough. You will be delighted with the results. Having a nice patio in the yard opens up a world of opportunities for you in terms of outdoor living activities.

Detailed Instructions for Building a Concrete Patio

1. Building concrete patios requires some planning. Buy materials and tools ahead of time, and rent an automatic cement mixer. Concrete calculator: to cover 50 square feet, 6 inches thick, you will need 25 bags (buy the pre-mixed kind to expedite the project). Prior even to planning the project in any detail, you should phone the Call Before You Dig number to ensure that you will not be damaging any utility lines underground.
2. Excavate with a garden shovel. In the North, go down to a depth of 6 inches. Two of these inches are for a bottom layer of gravel and the other four for the concrete. The gravel layer is meant to prevent your concrete patio from cracking during the freezing-thawing cycle. Make sure you establish a grade that slopes away from the house, for runoff. You can determine the grade by inserting stakes at the high end (up against the house) and low end of the excavation, then hanging a string between them. A line level placed on the string will indicate the present grade. Excavate so as to end up with a slope of about 1 inch for every 4 feet.
3. Build a form out of lumber (scrap lumber is fine, because forms are kept in place only for a short time) to hold the gravel and concrete. Sink the form into the area excavated for the concrete patio. The top of the form should be level with the ground, if you want your patio floor to be flush with ground level.
4. Install gravel, tamping it down firmly. Install 2-inch-high, flat pieces of rock (this is an opportunity to rid your garden of some rocks) as supports for rebar reinforcing, which you must build approximately in the middle of the 4-inch-thick concrete slab.
5. Install reinforcing rebar to unify the slab. Make a grid by placing them at every 2 feet both from front to back and from left to right. Unite them with wiring at intersections.
6. Mix concrete in a rental automatic cement mixer, first adding water with a garden hose to the mixer, then concrete, then water again -- until the mix becomes a uniform, shiny, medium gray.
7. Pour the concrete, starting at the end farthest from where your mixer is, building a ramp if necessary. Add filler rocks as you go. Pour as fast as possible. Preparation is crucial here.
8. Use a screed  (the process is also called "screeding") to level the surface of the concrete, sliding it along the top of the form boards. Pull the screed from one end to the other, drawing off excess concrete.
9. Cut initial control joints into concrete patio at about every 3-4 feet with a mason's trowel (not a garden trowel). Make them 2 inches deep. To achieve a straight cut, place a board across your forms at right angles to serve as a guide.
10. Look for a watery layer to appear on the surface of your concrete (which is said to "bleed" as it settles). After this watery layer appears, wait for it to disappear before proceeding.
11. Use a float to even out any lumps on the concrete patio. Sweep it in an arc-shaped motion, keeping the edge at the front of your sweep slightly raised, lest the float dig into the concrete surface.
12. Finish the control joints begun in Step 9. Use a jointer to make a clean groove, about 1 inch deep (or 1/4 the depth of the total slab). Re-use the same board as a guide.
13. Finish the concrete patio surface with design elements. Running a push-broom over the concrete patio makes a design both attractive and practical: lines that provide visual interest and a slip-resistant surface.
14. Lay plastic over the new concrete patio. Concrete must be "cured" properly. The key to curing is not letting it dry out too fast. By laying plastic over the concrete patio, you trap the moisture within. Keep the plastic on for a week. Concrete does not fully cure for 3 weeks, so even after you have removed the plastic, do not subject the surface to undue stress. In terms of applying a sealant later (which is recommended), how long you must wait before applying varies by product (sometimes, instructions will be supplied on the label of the sealant that you chose).
15. If you anticipate that there will be a large amount of water runoff from your patio and that this runoff will cause problems, you may want to look into having a drainage system installed in your yard prior to building a concrete patio. Once such an overall drainage system is in place, you can focus on drainage for the patio, itself. There are drains meant especially for patios, called "linear drains," and these drains tie into the overall drainage system for your yard.

 

Tips to Make the Project Go Smoothly for Beginners

1. Avoid skin contact with concrete, as well as inhaling the dust. Make use of gloves, kneeling boards, long pants, long-sleeved shirts, protective boots, goggles, face masks, etc.
2. In my area, the big home improvement chains have rental departments, where there is a 24-hour rate for automatic cement mixers. This rate is cheaper than the 10-hour rate offered by smaller rental service stores. When in doubt, buy extra concrete. You do not want to find out that you are a bag short just as you are about to put the finishing touches on your masterpiece and the concrete is starting to harden.
3. If you want to lay bricks on the concrete slab and end up with the tops of the bricks flush with the ground, dig an extra 2 1/2 inches (2 inches for the bricks and 1/2 inch for the mortar that will be applied between the bricks and concrete).
4. If, in your digging, you come across any stones, wash them and set them aside to be incorporated into the concrete. They will take up space and save on concrete usage. It is also a good time to dispose of garden rocks.
5. If you are digging 6 inches down, 2x6 lumber makes for ideal form boards. But since their tops will be flush with the ground, prevent debris from falling in on your project by covering the landscaping area with tarps.

 

List of Supplies You Will Need

1. Pre-mixed concrete
2. Automatic cement mixer
3. Gravel, screed, float
4. Four 2x6s (to build the form), scrap boards
5. Nails, garden shovel
6. Rebar, wire
7. Garden hose
8. Trowel, jointer
9. Protective clothing, mask and goggles
10. Line level
11. Concrete sealant

 

The Next Step to Take

Now that you know how to build a concrete patio, you may be curious as to how to place your own unique stamp on your project. Many homeowners insert objects (decorative stones and the like) into their patio floors to enhance their beauty. I offer a tutorial on inserting an inlay into your concrete patio. But the possible options here are numerous; to a large degree you are limited only by your imagination.