Build the Perfect Pitcher's Mound
Step-by-step guide to constructing a mound on your ball field
A perfect pitcher's mound gives your team a home field advantage and protects your players against injury. We've put together this step-by-step guide to help you build the perfect pitcher's mound. Based on an article written by our expert for Sports Field Management magazine, here’s all the information you need to make your pitcher's mound top of the game.
The Basic Dimensions
A pitcher's mound for high school through Major League comprise a circle that is 18 feet in diameter and 10 inches higher than home plate. Note: That's 10 inches higher than home plate and not the grass level.
Have the Tools at Hand
There are many methods for building a pitcher's mound and this is the one our experts favor for its simplicity.
First, make sure you have the equipment and supplies needed:
- Plate compactor
- Hand tamp
- Landscape rake
- Carpenter's level and carpenter's square
- Hose and a water source nearby
- Professional block-type, four-way pitching rubber
- 100-foot tape measure (or laser)
- Steel spikes and string (or transit with laser)
- Wheelbarrow or utility vehicle
- Specialty packing clay
Pay Attention to the Clay
While most of the supplies listed above are fairly generic, the type of clay you use makes a difference in the construction and quality of your pitcher's mound. Our experts prefer using two types of clay: a harder clay on the plateau and landing area of the mound and a regular infield mix clay for the sides and back of the mound.
The harder mix has more clay and is typically made up of 40 percent sand, 40 to 50 percent clay, and 10 to 20 percent silt. The infield mix is about 60 percent sand, 30 percent clay, and 10 percent silt. The bagged mound mixes you can buy from suppliers vary widely. Some of these mixes come partially moist, some are almost muddy, and others are dry as desert sand. Take note of this when you're sourcing the clay for your pitcher's mound. It’s best to use mound mixes that are heavy in clay and easy to work with.
You can also purchase bricks of harder clay. These come packaged moist and ready to go in the ground. It's up to you if you'd rather go with the bricks or a bagged mix. Our experts prefer the bagged mix because they offer more flexibility when it comes to establishing moisture levels.
In terms of supplies, you'll need about 8 to 10 tons of clay to build your mound, that's 2 tons of the harder clay and 6 to 8 tons of the infield mix.
Set Your Distances and Heights
The most accurate way to set your distances and heights is to use a transit with a laser. If this isn't possible, you can also run string between steel spikes and use a bubble level clipped on to the string. The third alternative is to build and use a slope board.
Get the Proper Orientation
Start by mapping out the proper orientation for your pitcher's mound. You'll want the line from home plate through the pitcher's mound to second base to run east-northeast. This ensures the batter won't be looking into the sun while facing the pitcher.
As you get ready to construct the mound, use the transit and laser (or string lines) to ensure home plate, the pitcher's mound, and second base are accurately aligned and that everything is square.
Major League Baseball (MLB) regulations call for the distance from the back of the home plate to the front of the pitching rubber to be 60 feet and 6 inches. As mentioned previously, a typical pitcher's mound is 18 feet in diameter with the center of the mound 18 inches in front of the pitching rubber. That makes the measurement from the back of the home plate to the center of the pitcher's mound 59 feet.
Note: Often, the rubber is accidentally placed in the center of the pitcher's mound. Be careful with your measurements and don't fall into this trap. Also, protect any grass already in place with geotextile and plywood while you're building the mound.
Now you're ready to begin.
Make the Measurements
If you're using a string line, place one steel spike behind the pitching rubber location and one a little beyond home plate. Put a pin at the 59-foot point in the center of the mound area and stretch a 9-foot line out from it, moving it all around the pin to mark the outer line of the 18-foot circle.
Leave the pin in the center and place a second pin where the pitching rubber will be. Mark this pin at 10 inches above home plate.
Bring in the Clay
Start bringing in the clay to form the base of the mound. It's important to establish the right moisture content within the clay mix. The desired consistency should be a bit drier than that of Play-Doh® when it first comes out of the can.
Lay the Levels and Build the Sub-Base
Build the mound in 1-inch levels, establishing the desired degree of moisture in each one to ensure each level adheres to the next. Use a tamp to compact each level as you build. To make it easier to tamp down each level, put down plastic or wrap the tamp with a towel or piece of landscape fabric to keep it from sticking to the clay.
Make sure the hard clay used to build the plateau and landing area is at least 6 to 8 inches deep. Do not add soil conditioner between these layers as it will keep them from bonding together. Check the height measurement with every lift of the clay by using the transit and laser or the string line.
Construct the Plateau
When you've built up the sub-base with hard clay at the 60-foot-6-inch area to a 10-inch height, you can start constructing the plateau. This should be 5-feet wide by 34-inches deep. As noted earlier, make sure the pitching rubber is positioned 60 feet and 6 inches from the back of the home plate. Now, ensure that it's set firmly in place and is level across the length and width with the top surface 10 inches above the level of home plate.
Reconfirm your measurements: Draw a centerline through the pitching rubber and run a string from home plate to second base to confirm the pitching rubber is centered properly.
Once the pitching rubber is in place and the plateau completed, you can begin to build the slope toward the front of the mound.
Build the Mound Slope
Providing a firm, consistent platform on which the pitcher can execute a pitch and transition easily to other bases can help prevent injury. Begin the slope 6 inches in front of the toe plate, creating a drop of 1 inch for every foot of measurement. Double-check the accuracy of the slope using the transit and laser or the string line.
To create a firm platform for the pitcher, use the harder mound clay to create the pie-shaped front slope of the mound. Use the same method of clay mix, water, and tamping, working in 1-inch increments.
Use the infield mix to construct the rest of the mound. Using the same layering process described earlier, begin working from the back edge of the plateau. Use the edge of the slope board or wooden plank, positioning the top edge on the back of the plateau area and the other edge of the board on the edge of the grass to guide the degree of slope for the back and sides of the mound. If you're using a plank, be sure the board is turned on its side so the mound supports its 2-inch side.
Looking at the mound from the front as a clock face, the area you're working on is basically from 9 a.m. to 3 p.m. On the back, you'll want to create a smooth area so that the side section precisely meets the edge of the pie-shaped wedge that makes up the front of the mound. Upon completion, the mound should look like a continuous circle with no indication that different materials were used in its construction.
Here's the math: The dimensions, working from the outer edges of the 5-foot by 34-inch plateau make the back and side segments a perfect fit. They tie into the wedge with the 1-inch to 1-foot drop of the front slope that begins 6 inches in front of the pitching rubber.
Add the Finishing Touches
Once the mound is completed, top it with 1/8-inch layer of infield conditioner so it won't stick to the tamp. Next, cover the mound with a tarp and keep it covered to prevent it from drying out and cracking.
Play Ball and Perform Regular Maintenance
Now that you've built the perfect pitcher's mound, the only work is the easy, but ongoing management of moisture levels as you repair the mound after every practice and game.
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