How to Secure Slate Steps to Cinder Blocks

Unlike other building materials for steps and staircases, which can typically be nailed or bolted together, a rock slab, such as slate, can't be easily secured to a concrete cinder block base by pounding through a reinforcing bar. Instead, the two surfaces need to be stuck together in the same way that most most masonry units are, by adding a strong adhesive mortar between them. As seen in brick and stone walls, mortar is a strong, waterproof substance that is applied easily.

Cinder blocks
Slate steps
Level
Thinset mortar
Bucket
Trowel
Water

Instructions

- 1
  Check that the cinder blocks are level on the surface for the stairs. If the blocks are not level, use a leveling agent, like LevelQuik, to correct the tilt. Let the leveling agent dry completely before proceeding.
- 2
  Mix a batch of mortar in a large bucket. Use clean water and stir the mortar with the trowel. At the right consistency the trowel can stand upright on its own when stuck in the mortar.
- 3
  Wet the cinder blocks so they don't suck the moisture from the mortar too quickly.
- 4
  Spread the mortar over the cinder blocks with the trowel. Apply the mortar to the middle of the block and spread it outward. Place the mortar down as needed one step at a time so that the slate can be laid before the mortar starts to dry.
- 5
  Lay the steps down on the still wet mortar. The compound should take 24 hours to secure.

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