In a previous question, Why do many concrete blocks have this strange shape on either end?, I asked about the design of the concrete blocks having an I-shape at the ends.

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That explains how to make a strong wall, but how does one go about using these strange-shaped bricks to make a 90 degree corner? Assume the bricks are positions such that the holes point upwards for rebar to be placed, won't that make the strange I-shape visible in the corners?

3 Answers 3


Here are a couple of pictures from the garage I had built, showing the blocks Ecneral referenced.

enter image description here

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  • Notice that the holes in the corners are filled to help hold the corner together, in addition to the rebar run up through them.
    – FreeMan
    Commented Jan 27, 2021 at 17:01
  • Nice. Two full size corner blocks, and a full size and half-size sash block visible there. Good picture. +1
    – Ecnerwal
    Commented Jan 27, 2021 at 17:02
  • I can only take credit for the pictures <wink>. The masons did all the good stuff.
    – SteveSh
    Commented Jan 27, 2021 at 17:27

You purchase corner blocks. Those are stretcher blocks for the middle of the wall, not corner blocks. A masonry supplier will have a variety of different shapes for particular purposes, one of which is corners (both full and half-blocks)

There are also special shapes for door/window openings (sash blocks and lintels), bond beam blocks for horizontal rebar placements, etc.

You might want to search on "CMU construction methods" (CMU is "concrete masonry unit" or the formal name of the concrete block.)


Here is one type of concrete block that will enable the construction of a smooth angular corner:enter image description here

When laying block for a wall it is best to start at each corner and work inwards. The corner's need to be interlaced; that is each row must be at right angles to the other for maximum stability and strength.

Use the smooth faced block for he corners and the other type (stretchers) for the intermediary section of wall.

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