How to Build a Concrete Driveway | Pouring Concrete Driveways
First, because of extra weight requirements, driveway construction is often well-regulated by local building codes. Make sure you understand all code restrictions before you start construction. You also must have the proper building permits. For example, most municipalities have strict rules governing the steepness, thickness and width of a driveway-as well as the means by which it joins the curbing.
The first step, therefore, is to find out any code restrictions and then sketch out your driveway plan. Submit this plan to the building permit officials when you go to get the building permit for the project.
How to Build a Concrete Driveway – Design Considerations
Most single driveways today are formed with a single slab instead of double-slab ramp drives that has paving only where the car wheels go and grass between. A single slab provides a wider usable surface to serve the wheel base dimensions of more car models. The trend of the times has reinforced the single slab, perhaps partly because a single slab requires less edge forming. Two-car driveways must be a full-slab design.
The Garage and Street-The edge of the driveway should fall about 1 inch below the garage floor to prevent water from running into the garage.
The driveway should slope downward from the garage to the street. If the garage sits downhill from the street, install a drain where the driveway meets the garage. Where the driveway meets the street, raise the edge of the driveway just a tad above the road to prevent water and debris from flowing from the street into the driveway.
How to build a concrete driveway
Driveway Size-In most cases, the driveway is cast so it is 2 inches above ground level.
Slabs for passenger cars are 4 or 5 inches thick. However, a slab that will have truck traffic should be 5 or 6 inches thick. Some contractors make the area near the street 8 inches thick to accommodate the extra weight of trucks that might pull partly up onto the driveway for delivery or collection.
A slab for a single-car garage should be between 8 and 10 feet wide. A slab for a double-car garage should be between 15 and 20 feet wide. Widths up to 22 feet are common, and you ought to consider this dimension.
Pitching The Driveway-The driveway should also provide a pitch of from 1/4 to 1/2 inch to the foot. This is considered a minimum in most areas. You can give a sideways pitch to the entire drive, but the best plan is to crown the driveway, providing pitch from the center to both sides.
To create the proper pitch from the center to the edges, the slab is placed in two stages. First, the form for the entire driveway is built. Then a centered stop board is inserted lengthwise in the form. It runs from the garage to the street, and must be high enough to create the correct pitch.
If your driveway is to be 20 feet wide, the center of the placement must be 5 inches (10-1/2 inch) higher than the outside edges of the slab. The form boards at the garage and street must correspond to this pitch, and the top edge of the centered stop board must be 5 inches higher than the side form boards. The center joint between the two sections of the slab will be held together with a butted construction joint.
Excavating/Base Materials-Lay out the dimensions of the pour and excavate as needed. The depth and width of an excavation depends on the project, its specifications and codes.
A correctly prepared excavation has several characteristics. A uniform sub grade ensures a consistent response to temperature and moisture changes. Level the earth surface so there are no deep holes or protruding objects. Remove all large rocks, roots, and other debris from the area. Tamp the sub grade, either with a hand tamper or a mechanical one. The sub grade should follow the angle or slope of the ground.
Setting the Grade-Set the grade for the driveway by staking it and leveling it, as ring Stake B shown in illustration A. Excavating is easier to do from this level string point as is building the concrete forms. Construction joints occur (B) since a long driveway must be laid in sections. Key the Slab 1 ” below garage floor sections, if the slab is more than 4 inches thick or butted if 4 inches or less. A construction strip is used at the center of a driveway (C) pitched from the center to each side for adequate drainage. If the driveway runs downhill toward the garage, install a drain for water. Construction or control joints are very important in large slabs of concrete. They help prevent the concrete from cracking and heaving due to frost and rain and normal settling of the slab.
Base materials of sand, gravel and rock are placed at the bottom of the excavation to prevent settling and heaving and to aid drainage. They also provide a level surface on which to place the concrete.
The depth of the base is often regulated by codes. Find out how much base you need as you did for concrete, but order twice as much as your figures indicate. This is because the base materials will compress to half their original size when tamped.
Order of Placement- First, place the gravel in at least two layers. Tamp each layer so the top of the final layer is 2 inches below the bottom edge of the concrete pour. Then add sand. Keep adding and tamping until you have a level layer that reaches to the top of the pour. Follow this order. The depth of any given layer may vary according to code. The level is checked with a strike board that you make.
How to Build a Concrete Driveway – Building the Concrete Forms
At entryways, for better appearance and easier access, use curved forms to provide curved entryways on both sides where the driveway meets the street. Use 1/4-inch plywood cut in widths to match the concrete depth dimension and stake the plywood as it is bent into a gentle curve. Use plenty of stakes to prevent the plywood from bulging when the concrete is placed into the form.
Concrete takes the shape of the mold in which it is placed. In most cases, the mold is made of 2X4, 2X6, or 2X8 lumber supported by 1X2, 1X4, or 2X4 stakes.
To build the form, position two parallel boards in the excavation so that their inside edges form the driveway sides. Drive stakes in place next to the ends of the form boards. Starting at the ground level’s highest point, raise the ends of the boards up with their top edges about 2 inches above ground level. Check for level with a carpenter’s level across the tops of the two form boards. Run a straightedge across the forms so it bridges them. Then set the level on the straightedge.
Fasten the forms to the stakes with duplex (double) headed nails. If the tops of the stakes are not flush with or slightly below the top edge of the forms, saw them off once the form is completed. Raise the opposite ends of the boards up to suit-either following the contour of the ground or raising them to match the desired pitch. Then drive stakes, spaced every 3 f. along the form boards and nail the stakes to the form boards. Install a stake at any location where two form boards butt. Nail the stake to both boards. If the ends of the boards are angled or uneven, square them with a saw before nailing them into position with double-headed nails.
Oil the form boards with old motor oil applied with a paintbrush. The oil will prevent the forms from sticking to the concrete. The oil also prevents water in the concrete from being absorbed by the forms, thus weakening the concrete mixture.
Once the forms are in place, including the centered stop board, double-check all measurements. Then order any necessary reinforcing mesh, cut it to fit inside the forms, if needed, and elevate it with stones or brickbats about half the distance from the grade to the top of the form boards.
How to Build a Concrete Driveway – Now, the Concrete
When you’re satisfied that the forms are ready, order the concrete for the job. It is strongly recommended that you use a ready-mix service; the time and work you will save in not mixing the concrete yourself is worth the added expense. The ready-mix company will need to know the dimensions of the driveway between the form boards: the length, the width, and the depth (overall average). The concrete folks will fill your order accordingly. Tell them your plans.
If the driveway will be crowned, you will place one section of concrete at a time. Tell this to the ready-mix company. Schedule a date for the pour with the company and be ready when the truck drives up. It is suggested that you enlist the aid of a couple of friends to help you with the placement. Once dumped out of the concrete truck, you’ll have to work fast to level the concrete with shovels and then screed (level) the top with a straightedge. It’s hot, heavy, and fast work.
Start the pour at the garage and work toward the street. If you lay the length of the driveway in sections, install a stop board at about 10 feet. It will then correspond to the placement of control joints. Place the concrete in this first section only.
Tamp and spade as needed, giving special care to edges and tie bars. Screed the concrete off (work a straightedge zigzag fashion across the top of the form boards) and place it into the adjacent, unpoured section. If you don’t screed, some places will have a lot of extra concrete, which must be moved. Other spots won’t have enough.
Let the slab set up. Cut any control joints as needed, insert any expansion strips, and give the driveway a lightly broomed finish after you float and finish-trowel the surface fairly smooth.
The Final Pour- Once the first half of the slab is finished, remove the stop board. This is not easy. It is hard to slip the tie bars back through the holes in the stop board. Repeat the entire process for the remainder of the driveway, in 10-f. sections as needed to complete the driveway.
Curing- The concrete should be covered with burlap and the burlap kept wet for a week or so with a sprinkler head on a garden hose. You can skip the burlap, but keep the surface of the concrete wet.
If it starts raining as you finish the trowel and brooming job, cover the concrete either with burlap or newspapers so the raindrops don’t dam age the surface of the concrete.
Let the project set a couple of weeks, then strip off the forms and backfill any dirt needed to cover the surface of the concrete.
Bull Float is a little more than a handle with a board attached to it. The float is pushed and pulled along the concrete surface after the concrete has been screeded. The float produces a level, but slightly rough surface, which can then be troweled. You can buy bull floats or make them yourself. A “hand” float (looks like a trowel) also is handy.
Procedures check. To sum up the steps involved in placing a concrete driveway, use this quick checklist: 1. Find out the codes in your community.
2. Sketch the project, putting in dimensions. 3. Get the necessary building permits. 4. Excavate and prepare the base. 5. Build the forms (4 & 5 can be done together). 6. Double check all measurements. 7. Order the concrete. 8. Finish the concrete. 9. Protect the concrete until it has hardened. 10. Backfill and landscape.
How to Build a Concrete Driveway, How to Build a Concrete Driveway