Build a chimney

Empty the concrete for the base if you have not already done so. Install the base first, digging a trench and using a compactor blade to level the base. Mix and pour the cement and let it sit for at least 24 hours or more.

Check with local building authorities to see how deep the base should be. Some locations need concrete bases that are only 15 cm (6 inches) deep, while others need more than 30 cm (1 foot).

Note: Although concrete and mortar are similar, they are different adhesion agents and should be used differently. You will use the concrete as a base if necessary and the mortar to adhere concrete or concrete blocks.

Apply the mortar to the base and begin to place the layers of concrete or concrete blocks. Follow the building plans precisely, making sure each row of blocks is level.

When creating the base, be sure to use a level to ensure even placement of concrete or concrete blocks.

If you are going to use concrete blocks, apply the mortar between each row, as well as between the individual pieces.

If necessary, lay the refractory brick inside the combustion box. Special care must be taken when installing the refractory brick in the combustion box. Laying it in a nice pattern and using the proper mortar is an important consideration.

Choose a nice interior pattern for refractory brick. An asymmetric pattern works very well in a combustion box. Find the center of the combustion box and draw a line towards the front of the combustion box.

Place a refractory brick immediately to the left and right of the dividing line, fitted to the front of the combustion box, leaving about a half inch (1/4-inch) between the two. Place a brick immediately on the two bricks, exactly in the middle. On the latter, place two bricks in the same pattern as the originals.

Mix mortar with mortar for high temperatures. In this way, the high temperature will not compromise the mortar that holds the refractory bricks together.

When you set the bricks, cut it as necessary is the corners and edges. While you may not cut the center pieces of the combustion box, the corners and edges will force you to do so.

Remove the air bubbles from the mortar for the refractory bricks with a marker of joints and a brush. Apply the mortar at each joint with the marker. Then brush the excess mortar with a clean brush, letting the combustion box dry for at least 24 hours.