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Installing Concrete Pavers, Part Two
This article was published originally on 6/30/1995Last week's newsletter article dealt with colors, patterns and design techniques. This week's article gets to the fun part, installation.
If the area to be paved is grass or weeds, stake out the plan and use a non-selective herbicide such as glyphosate to destroy the plants. This should be done a week or two before beginning the project to allow sufficient time for the herbicide to work. Also arrange to rent a flat-plate vibrator and a masonry saw or guillotine-style brick/paver splitter for the proposed date of the installation. Additional tools you'll need include a shovel, rake, rubber mallet, screwdriver, carpenter's level, tape measure, wooden stakes, string, spray paint, a 10-ft. 2x4, two lengths of 1 1/4-in. diameter pipe, a hand-tamper, broom and safety goggles.
Preparing the paver bed is the most important step. Pavement performance is directly related to the quality of the soil and base material. If you haven't done so already, form a digging guide by staking out the proposed area and spray-painting lines between the stakes. Mark the grade with string tied between the stakes. If you are installing near the house or another building, make sure the grade slopes away from the house to ensure proper drainage. A proper slope is a drop of 2 inches in height for every 8 feet of length. Dig and remove the sod from the staked areas. For our part of the country, we must dig out enough soil to allow for 5 inches of base, 1 1/2 inches of sand, plus the thickness of the paver. Many pavers are about 3 1/2 inches thick so we'll need to remove 10 inches of soil from the entire area. Once the laborious task of removing the soil is finished, level the soil with a rake. Using the flat-plate vibrator compact the soil. A minimum of two passes at right angles is necessary to remove air pockets. Now we can begin laying the base. The most common material for the base is quarried gravel, 3/4-inch and smaller. If the paved area is to receive vehicle traffic, the small particles in the aggregate that pass through a Number 200 sieve should be kept between 5 and 11 percent. This will prevent settling and heaving of the surface. Lay the 5 inches of gravel and compact it using the vibrator. Again, at least two passes are necessary to remove air pockets. Make sure the base is level before adding sand. The final depth of the base should not vary plus or minus 1/2 inch over a 10-ft length. A common construction error is to compensate for inadequate base installation by filling in low areas with sand. The maximum sand depth should be 1 1/2 inches. Areas exceeding this depth will result in a "washboard" pavement surface.
Once the gravel base is level lay the lengths of galvanized pipe 8 feet apart parallel to each other. Add a 1 1/2-inch layer of concrete sand. Using the 2x4, level the sand by dragging it along the pipes. Fill in low spots with additional sand and remove sand from the high areas. Once the sand layer is level remove the pipes and fill the grooves with additional sand. Concrete sand performs well for paver installation because it does not have too fine a gradation. Do not use limestone screenings or stone dust in place of sand. These may not compact well and will degrade with time. Do not compact the bedding sand. The movement of the sand into the bottom of the joints between each paver is necessary to allow the pavers to interlock and spread weight loads.
It is finally time to install the pavers. Begin in the center and work outward to the edges. This way any trimmed pieces will be at the periphery rather than the center of attention. Set the pavers so there is 1/8 inch between them. Every 5 feet, check with a string line to see that the pavers are straight. If they need to be adjusted, pry them up with a screwdriver and reset them. Continue this procedure until the entire area is laid. Once the area is complete, install the chosen edging material to prevent the pavers from shifting. Some edging materials should be installed prior to adding the sand layer and the pavers. Make sure to follow the installation recommendations of your particular product. Fill in the spaces between the pavers with dry sand. This is easily done using a broom. Compact the pavers with a least two passes of the vibrator. Make sure all the joints are completely filled with sand when compaction is complete.
Your weekend project is now finished and it is time to admire and enjoy. When properly installed, pavers require little in the way of maintenance. They may develop surface blemishes from mineral salts leaching through them. This white, crusty film is called efflorescence. Cleaners are available to remove it if necessary. It will also weather away on its own. Moss often grows on pavers in shaded areas. If you find moss offensive, use a dilute solution of bleach and water to remove it. A common complaint is weeds growing between the pavers. They are easy to remove through hand pulling because their roots systems are quite restricted. Boiling water also works, as does the selective application of appropriate herbicides.
Year of Publication:
IC-470(17) -- June 30, 1995