How to Build an Outdoor Pizza Hearth

Mix the refractory cement into concrete according to the manufacturer's instructions. Generally, heap equal shovels full of cement, sand and gravel in a wheelbarrow. Add water slowly and mix it in with the shovel until the concrete is thick. Test for readiness by shaping a handful into a ball and seeing whether it holds without crumbling.

Place firebricks in a square on a flat, dirt surface in your backyard. Leave no gaps between the bricks. Arrange the bricks until they create a square that is between 25 and 35 inches on each side.

Spread the refractory concrete over the firebricks and smooth it out with a trowel. This creates the hearth base, which will support a dome where the fire will be. Allow the concrete to dry for 48 hours in warm, dry weather.

Pile enough damp sand in the center of the base to measure 18 to 25 inches high. Smooth the sides down so they are symmetrical. The dome should be about as wide as it is tall.

Bend the metal or cardboard sheet until it makes a semicircle. Push it into the sand mound to make the form for the door. Trim as necessary. The form and sand should create an igloo-shaped look.

Cover the sand mound and the form with two layers of wet newspaper.

Press refractory concrete over the newspaper with your hands. Start from the base and work your way up. Shape and smooth the concrete to create a 1- to 2-inch-thick oven dome. Smooth the concrete over the form where it meets the sand dome by about an inch or two.

Allow the concrete to set up about 12 hours. Test the door form by pulling part of it away from the concrete dome. If the concrete holds, remove the form. If it starts to sag, replace it and check every four to six hours after that.

Let the concrete dry for about 24 hours. Scoop the sand out through the door. Reach inside the dome and pull the newspaper down.

Let the concrete pizza hearth completely dry, about 48 hours. Light a small fire in the center of the dome to cure the concrete.

Light a medium wood fire when you are ready to bake pizza. Let the fire burn down to coals, then sweep them out and douse them in water. Sweep the firestone floor again so there are no bits of ash. Set the pizza directly on the stone floor, where the radiant heat will bake it. Use the backyard pizza hearth to bake pizza, bread, dutch oven dinners and more.