Adding a concrete patio can make a beautiful yard accessible and useful across the four seasons. For a yard to be truly inviting green plants and flowers need to be balanced with a place to be. In the Pacific Northwest grass is often too wet or the soil too moist for nine months out of the year. Concrete as a building material can be very economical if you can tackle the labor yourself and is still a very solid choice if you are paying for part or all of the physical work as well.

How do I begin planning?

• Decide what you are going to do on your patio surface and how many people you would like to acommodate. You may want room for a BBQ, a table and chair set, other random chairs such as a chaise lounge, or maybe even a portable fire pit. Too small of a surface gives a crowded feel or may result in a chair leg slipping off the edge into soft ground. If your yard is very small you may want to limit the patio to devote more area to green space. You are balancing aesthetics with utility. You may find you are best served with two smaller hard surfaces. You may want a large area that can acommodate many guests.
• Drainage. Consider the status of your yard’s overall drainage. If you need to change grading or add french drains, these should be considered first. Sometimes you have no choice but to let your yard drain onto your new patio, but ideally the patio drains away from the house and most or all of the yard drains away from the patio. Even in a yard lacking ideal grading and drainage the slab can still be elevated a bit and have a slight angle to clear water quickly.

Am I really able to do this myself? The work is very physical and you will want some help. At each stage you may find you want to hire others for that part or do some yourself. Here is the process:

• Excavation. How much soil needs to be removed? The minimum concrete slab thickness you will want is 3 1/2″ over a minimum of 3″ of base. If you decided on a 12′ x 18′ patio that means you must remove about 4 1/3 yards of soil or about 10,000 lbs and 5 trips in your neighbor’s truck. Though the 3 1/2″ slab thickness is adequate, your project will benefit from a thicker base, such as 5″. This provides a stable surface for your slab. Consider if you can use the soil somewhere in your yard such as in a landscaping mound. Use a 4′ level on a long straight 2 x 4 to check if your slab will drain as planned. Use the 2 x 4 to check for excessive mounds or dips in your plane. I prefer to dig down an extra 2 to 4″ around the perimeter for a thick border, either 6″ wide or just using shovel width.
• Forming. Should I hire a carpenter? After excavating out your patio shape plus an additional 3″ for forming, set perimeter forms by securing 2 x 4s with wood or metal stakes. Usually stakes are set about 3′ apart, closer if soil is loose. Screws driven with a cordless drill is the easiest choice, but make sure screws or nails are from the outside so that you can remove them after slab is poured. On the outside form parallel with your house, check to see that you have uniform distance from your house and that the 2 x 4 forms a straight line. You can use string, but you can trust your eyeball. After selecting end points for your side forms, check that your forms are square by measuring and comparing the two diagonals that would form an X across your square or rectangle. Adjust forms until these are very close. I like 1/4″. Some are happy with 1/2″ to 3/4″ since you probably won’t notice at that discrepancy. You will probably want a 2 x 4 running through the center of your pour to screed concrete to, and which will be removed after concrete is placed. Supporting stakes should not be driven as deeply and you will place them farther apart, like 5′ to 7′ to aid removal. Remember to have a 2 x 4 precut for screeding concrete to level of forming.
• Base. Think of how proud your 8th grade math teacher would be. The amount of base to have delivered is the total cubic area less the area for the slab. Any dimension in inches must be divided by 12 to convert to feet. Total cubic footage is divided by 27 to convert to cubic yards which is how base is ordered. For example: I have a 10′ x 17′ slab, and upon placing my screed systematically in various places I find that my excavation depth varies from 7 to 71/2″. I want my slab to be 3 1/2″. My base thickness will be the 71/4″ average less the 3 1/2″ slab for 3 3/4″. So, 10 x 17 x (3.75/12)= 53.125. Then dividing by 27 I find I need 1.97 or two yards of base. Similarly I will need (1.84) two yards of concrete. Sometimes it takes a little more than you think. I like to prepare a few stepping stone forms to use extra concrete. Some cut a 2 x 4 an inch shorter than the space ebtween forms, and attach stakes to the top side of each end, extending them out about 4″. This is used to screed your base to a consistent depth.
• Reinforcing. What was that ZZ top song Concrete and Steel about anyhow? While many redi-mix concrete suppliers offer reinforcing fiber as a mix option, most reinforcing is in the form of rolled wire mesh which is pulled up into concrete as you pour or a rebar grid which is elevated on concrete “dobies,” or on rocks. I prefer a tighter grid, say from 20″ to 30″ on center, with #3 (3/8″) rebar rather than wider spacing with #4. If you don’t have access to a rebar bender, #3 is easily bent around a hitch ball on a truck and can be bent over your knee. This is to have a continuous band around the perimeter, though not an absolute necessity. Overlaps are traditionally 40 diameters (16″ for 3/8″). Rebar is tied at overlaps and intersections using tie wire and lineman’s pliers. With practice you can get ties tight without breaking them. If you don’t have access to that bender/cutter you’ll need a metal blade in a circular saw.
• Pour day. Even if you’ve gotten this far by yourself, you will want help. Though with lots of experience under my belt I have poured and finished large slabs by myself, it is never fun and even less smart. You will want two other helpers and if they are free don’t chase away a third. If the truck can’t reach your pour site, you will want at least one construction grade wheelbarrow with the tire inflated to proper pressure. Homeowner garden wheelbarrows are not strong enough. You will need a bullfloat of wood or magnesium, usually 36 to 42″ in length with necessary poles, a fresno metal finish float with poles, hand wood trowels, hand metal finish trowels, a magnesium trowel, a metal edger, and plastic buckets to keep hand tools in water. Tell the concrete company what you are pouring and confide that you are new to this and they will set you up with the right mix. If not too hot a day they might suggest 5 sack, 3/4″ minus aggregate, in a 5″ slump, with water on the truck to add if necessary. It isn’t important that this makes sense.
• Concrete placement. Accuracy now saves time. Whether by concrete truck chute, wheelbarrow, or eight workers with 5 gallon buckets, place the concrete quickly starting the farthest away, and in shady spots before direct sun spots. Make sure you continuously screed the concrete level with form tops and fill in holes as you go along. Screeding is done with one person on each end of your 2 x 4 screed moving it back and forth in coordinated fashion as they each also pull excess concrete toward them. If another person is available they should pull back excess with a shovel or concrete rake, so that the load isn’t too hard on screeders, and fill in low spots in anticipation of screeders reaching that point. This process makes the surface uniformly level and knocks larger rocks down into the pour.
• Finishing. If you hired a pro, now is when you are really glad you did! Immediately after all concrete is placed and screeded, begin removing concrete off form tops and overspills from outsides. You can gentle tap the sides of the forms to provide a smooth surfaces when forms are later removed. If placement went quickly and it hasn’t been hot, you will need to let the concrete set up for a little while. Though concrete is science it becomes art at this point.  For decades the next step has been to use a jitterbug to knock the rocks down. This is the process of pounding down on the slab with a mesh tool when the slab is wet but will support your weight with your sinking only about 1/2″. Some use a rolling jitterbug cage on an extension pole. Very nice. Some use an electric screed after placement and then skip the jitterbig phase. Some use the wood float mentioned below.The next step will be to begin going over the surface with the bullfloat. If done too early you will lose the uniform level surface you have created and bring up too much cream. If done too late you will discover rocks that are not sufficiently below the surface and now don’t want to go down and you will also find it hard to work up enough cream. Magnesium, whether in bull float or handtrowel, will work up cream when needed over a wood float. For this reason some finishers will use a wood bullfloat early and a magnesium bullfloat later, though most stick to a single step here. There needs to be enough cream to produce a smooth surface but not so much that you are just pushing it around. The technique is like spreading peanut butter. If surface stops being spreadable and you are starting to drag up material, you are going past bullfloat stage. If necessary spray water over a section as needed to allow this process. If sufficiently smooth for the bullfloat phase it is time to wait again.I like to go around the perimeter with the edger early to knock down rocks. This is a finish tool that will be used later when concrete is hard enough to metal trowel, but a preliminary pass will save you headaches.Concrete is ready for the fresno hard metal finish trowel when there is enough cream to smooth out but the tool does not produce an excess. At the right stage the fresno will work, whereas if you tried to use the bullfloat you would drag up material and have a problem to fix. If you are going to use a broom finish, you may do usually all your final smoothing with the fresno. After it dries to the point where a broom produces fine lines without making deep lines and dragging up material it is ready for the broom finish. If opting for a smooth finish, you can be satisfied with what the fresno can produce, but traditionally the hand finish process is added. This is done by going out onto the slab on plywood squares with 2 x 4 handles you have made for this purpose. The slab has to be hard enough to support this without sinking and you work backwards from your starting point finishing over any marks made. The lead edge of the trowel is lifted slightly to smooth out the work and avoid digging in. Alternatively, like peanut butter, you lift one edge then the other as you go back and forth. Additionally you will often add sweeping circular motions. Invariably you will have to use a magnesium trowel to work up some cream in a trouble spot before refinishing with the metal trowel. Remember to use your edging tool again.

Do it yourself and hire a contractor?

As you can see there is a lot of work and planning involved. If you hire this done, your builder is earning his keep. If you decide to tackle something like this yourself you can save a lot of money because you are taking on a lot of work. Perhaps neighbors can form some teams to complete projects in each others yards. For some this is a very sensible option and at times the only affordable one. For probably most, this is beyond their scope, and they will want to hire the labor and expertise of professionals for at least some of this.

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