How to Build a Chimney Using Blocks

Examine the location that you are planning to build the chimney and ensure that its foundation is adequately strong. In a house with wood floors, you will need to begin the chimney in the basement and build up through the floor to support its weight.

Lay a 1/2-inch thick bed of mortar to start the chimney.

Set a course of blocks, or a single block if you are using chimney blocks, into the bed of mortar. Specialized chimney blocks are far better for this job because they will take less work and will use up significantly less space when the chimney is finished. Seat the block by tapping it firmly into the mortar with the handle of the trowel.

Check the level of the first block by laying a 4-foot level across its top. It's critical that the first few blocks are perfectly level.

Spread a smooth 1/2-inch-thick layer of mortar over the top edge of the first chimney block and set another block on top of it, seating it in the mortar by tapping down on it firmly with the handle of your trowel. Check the second block to ensure that it's level.

Set a flue section into the hole in the middle of the blocks. Because the flue sections are taller than the blocks, you will only need to add one for every three layers of blocks. Seat the flue section into the mortar on the floor by tapping on it firmly.

Increase the height of the chimney by alternately adding courses of blocks and flue sections until your chimney has reached the required height.