How Do You Build a Block Chimney?

To build a block chimney, create a layer of mortar onto a solid foundation, then alternate adding specialized chimney blocks, mortar and flue sections until the chimney has reached its desired height. Specialized chimney blocks make chimney construction significantly easier.

Use the following steps to create a simple chimney system that will ventilate harmful gasses, fumes and smoke away from a fire or heating source.

  1. Find a solid foundation for the chimney
  2. Chimneys are typically made with heavy cement blocks. For this reason, the foundation of the chimney must be able to withstand a significant amount of weight. Chimneys that are made on wood floors must be built up from the concrete below the floor.

  3. Set the mortar and lay the first block
  4. Lay a 1/2-inch layer of mortar and set the first chimney block into the mortar. Seat the block deep in the mortar, and use a level to make sure that the block is perfectly level. If the first block is not level, the integrity of the entire chimney becomes compromised.

  5. Continue adding blocks and inserting flue sections
  6. Add another layer of mortar onto the first block, then seat another block on top of it. Insert the first flue section in the opening at the center of the blocks, and then build up a few more blocks around it. Continue this process of adding flue sections and blocks, making sure that the blocks are perfectly level until the desired chimney height is reached.