I am installing a brick patio around a pool. The brick is placed on compacted gravel topped by a 2-inch layer of sand. The sand must be smooth and even so that the finish bricks look right. How do I establish the proper heights for all of these materials?
First, establish the final finished surface height. In your case, it is the finished edge, or lip, around the pool. In the case of a regular patio or sidewalk, you might determine the finished surface by the surrounding ground or the relationship between the surface and nearby steps, decks or driveways.
The next thing to consider is the slope you want in the finished surface. Slope allows rainwater to run off the surface. You want water from the surface to drain away from your pool. A gradual slope of [ inch of drop per every 2 feet of run should be enough in most instances.
I prefer to establish grade stakes driven into the ground for reference points. The tops of these stakes represent the different heights you need to hit. For example, you need three different grade-stake elevations: one for the height of the compacted gravel, one for the uncompacted sand and the final one for the finish brick at various points around the pool.
These stakes need to be placed perhaps 8 feet on center so you can set a straight piece of wood or a metal straightedge on top of the stakes. If there is a gap under the wood or straightedge, this tells you that more material needs to be added. If too much material is placed, then the straightedge will not rest upon the tops of the stakes.
When you have the perfect amount of material in place with respect to the given stakes, the surface will be perfectly smooth as you and a helper rotate the straightedge on top of any of the stakes, just as the hands of a clock rotate around the dial. The network of stakes allows you to move the straightedge to different stakes to check that all points are in the same plane.
Establishing the proper height of the stakes can be a challenge. For years I have used my builder's level or transit to do this. My level looks similar to the expensive transits that surveyors use, but all my instrument does is establish a level sight line as you look through it.
By using a graduated grade pole on top of each stake, I can tell if the stake is level, or in the same plane as all of the rest. A grade pole is simply a vertical ruler that is marked in increments of \ inch. The person looking through the builder's level focuses on the grade pole markings to determine how high or low the top of a stake might be.
For example, once my instrument is set and level, I look through it. If the grade pole is resting on top of the pool edge and reads 4 feet 1 inch, then I need to make sure the top of the stake representing the finished brick produces a reading greater than 4 feet 1 inch. This "greater amount" is a function of the amount of slope I am trying to create at any given location. So if I am, say, 6 feet away from the pool edge, the reading looking through the transit might be 4 feet 1] inch. Since the instrument is projecting a straight line as you look through it, any reading that gets bigger means the bottom of the grade pole is dropping.
You can often rent builder's levels or laser leveling equipment at tool rental shops. The store manager should be able to give you a quick tutorial. You will be amazed at how well these tools work so long as you get them level before you use them.
Not all grade stakes will always be at the same elevation. If the pool patio is not a consistent width around the pool, the grade stakes farther from the pool edge will be lower and lower as you continue to create fall as you move away from the pool edge.
It is always best to make a written plan of the grade stakes and confirm the mathematics. You can also string lines if the stakes are in line with one another. The string will show whether one stake is higher than an adjacent one.
Of course, the builder's level will do the same thing as long as you keep track of the different stake heights. See why I wanted to come over to help?
Tim Carter is a licensed contractor. Got a question for him? Call from 6 to 7 a.m. today at (513) 749-1035 on his radio call-in show on WGRR-FM 103.5 in Cincinnati. You can listen to his archived radio shows online at any time by clicking on www.askthebuilder.com/ cgi-bin/multimedia. To view previous columns or tap into his archive of information and sources of building materials, visit Ask the Builder on the Web at www.askthebuilder.com.
There are several ways to level sand or gravel, but a transit or builder's level is the columnist's choice.