5. Fit the cement block to the pattern youve laid out on the floor with the lath and plastic.6. Mark the back of the block where the cuts will take place (figure B). Use a circular saw with a masonry blade to actually make the cuts.
7. Place block into position in front of the fireplace.
8. Mix concrete, then fill each block with concrete to about 3" deep (figure C). Push concrete down so it will settle evenly.
9. After the concrete has dried, use a level to make sure the hearth is still straight.