How do I Attach Cinder Block to Concrete Slab?

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Things You'll Need

  • Tape measure

  • Spray paint

  • Shovel

  • Concrete

  • Cement blocks

  • Mortar

  • Trowel


The size and height of the wall or structure will determine whether it needs to be reinforced with rebar and concrete.


Review your city codes before building any wall. Your city may have height restrictions for fencing and other walls.

Cinder blocks are a great tool for building garden walls or storage structures in your yard. Any structure that you build will be more stable when it is set on a solid foundation. If the area where you are planning to use the cinder blocks is already covered with a concrete pad, you can easily build a cinder block wall right on top of the concrete.


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Step 1

Set out the first row of cinder blocks without mortar, and adjust and move your wall as needed until you are satisfied with the layout. Draw an outline of the wall on the concrete with chalk, and then remove the blocks.

Step 2

Mix the mortar according to the directions on the package. Mix the mortar until it has the same consistency as toothpaste.


Step 3

Fill a mortar board with mortar. Pick up a small amount of mortar with a trowel and place the tip of the trowel on the concrete. Move the trowel backward while twisting the it 180 degrees to spread the mortar onto the foundation. Place a 1-inch-thick bed of mortar along the concrete foundation.


Step 4

Set the first cinder block firmly into the mortar. Press down until the mortar joint is 3/8 inch. Spread a vertical bead of mortar along the side of the block with a trowel.

Step 5

Set a second block next to the first. Tap the cinder block lightly with a rubber mallet to slide it closer to the first. The mortar joint between the two blocks should be 3/8 inch. Remove excess mortar that squeezes out from between the blocks with the tip of the trowel. Add more blocks until you have attached the entire first row.