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How To Lay Cement Block

Cement blocks provide an easy, cost effective material for the homeowner where a project is too small or too inaccessible for a concrete pour. A semi-hollow product that comes in a number of different sizes and configurations, you can purchase cement blocks individually, by the pallet, or by the truckload. A successful job with cement blocks depends on a plumb, level, solid foundation.


Laying cement blocks is fun and rewarding

Laying cement blocks is fun and rewarding

  1. Build your foundation with form lumber, bracing, and ties. Make sure it is shot in with a tripod level or transit to a true, accurate benchmark and that it is square, plumb, and level.
  2. If you are going to lay up cement blocks on a concrete slab, drill the slab at intervals and install lengths of reinforcing rods to anchor the block wall to the slab.
  3. Mix your mortar to the proper ratio and consistency. Two and a half bags of mortar mix to 600 pounds of sand will lay 100 cement blocks. You can also buy premixed mortar in bags.
  4. It is best to only mix up enough mortar to use in one to two hours.

Laying cement blocks

  1. Lay out the corners of your wall on top of the footing.
  2. Lay out the first course of blocks without mortar but leaving a space for it between each block.
  3. Snap a chalk line to indicate the first course of blocks and remove them.
  4. Lay down a heavy base of mortar along the chalk line and wider than the cement blocks.
  5. Furrow the mortar base with the point of your trowel.
  6. Stand the first course of blocks on end and apply a layer of mortar to the vertical face.
  7. Lay each block in the mortar base in turn starting with the corner block. Make sure you lay the blocks down with the wide face up.
  8. After laying two or three blocks, align them to the chalk line or to a stretched mason’s line. Tap them into alignment with the handle of the trowel.
  9. Use a four foot level to plumb and level the first course of blocks.
  10. Lay up the corners first at least four or five courses high.
  11. Follow this same procedure to finish laying all the remaining courses of cement block.


Apply mortar to the vertical face of the previously laid block or the new one, but not to both.

After one course is laid, apply mortar to the top horizontal face of the first course.

Make any adjustments while the mortar is still wet.

Trim the mortar joints with the point or side of your trowel as you lay each block.

After the mortar has partially dried, trowel the joints with an s shaped joint tool.

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