How to Create a Cinder Block Foundation

Pouring the Footing

• 1

  Mark a pair of parallel lines for the footing by driving stakes with a rubber mallet. The two lines of stakes must be double the width of the cinder blocks.

• 2

  Dig a one-foot-deep trench between the two rows of stakes. Compact the bottom of the trench with a dirt tamper. Lay a carpenter's level on the floor of the trench to check that it's level, move dirt as necessary with a shovel and compact again. Pull up all the stakes.

• 3

  Dump gravel from a wheelbarrow into the floor of the trench. Shift the gravel into an even, six-inch-thick layer with an iron rake. Compact the gravel with the dirt tamper, check that the surface is level with a carpenter's level. Add or subtract gravel as necessary to make the layer level, and compact it again.

• 4

  Line the sides of the trench with 2-x-12 form boards. Secure the boards by driving stakes behind them and driving nails through the stakes and into the boards.

• 5

  Mix and pour foundation-grade concrete into the trench, filling it. Compact the concrete with a bull float, wait for water to condense on the surface, let the concrete absorb that water and then smooth the surface down with a magnesium float.

• 6

  Allow the concrete footing to harden overnight before continuing.

Laying Cinder Blocks

• 7

  Mix a batch of mortar sufficient for half an hour's worth of work. Continue mixing fresh batches as necessary.

• 8

  Spread a layer of one-inch-thick mortar with a mason's trowel on the footing to form a bed. This bed must be as wide as the blocks and long enough to lay three or four cinder blocks.

• 9

  Lay the first block in the corner and settle it into place by tapping around the top of the block with the bottom of the trowel.

• 10

  Spread two lines of one-inch-thick mortar on the end of a fresh cinder block, along the outside edges of that end. Place that block next to the corner block so the end with the mortar is nestled against the corner block. Settle it down by tapping the top with the butt of the trowel.

• 11

  Continue laying blocks by repeating Steps 2 and 4. Lay a carpenter's level across the top of the row after every second or third block to check that it's level. If the row isn't level, remove the offending block and reset it.

• 12

  Cut cinder blocks to fit smaller spaces by chiseling off "cells." Every cinder block is divided into hollow cells by internal dividers. Draw a line on the top and bottom of the block just outside the appropriate divider. Cut a groove into those lines with light chipping from a hammer and cold chisel, and then split off the undesired part of the block by striking those grooves with hard blows.

• 13

  Alternate the direction of the corners with each new row of blocks. If you are standing outside a given corner and the corner block points left, the next row's corner block must point right.

• 14

  Fill the cinder blocks after laying four rows by pouring mortar into the hollows. Insert a steel rebar into every other block by pushing it through the wet mortar and down to the bottom.