How to build a small concrete block storage building

Updated February 21, 2017

Concrete block provides a safe, sturdy and economical way for building construction. When building a storage building, one should consider concrete block as an alternative to wood construction. To successfully build a small concrete block storage building, you must pick the right materials and follow a series of methodical steps to completion.

Form the concrete pad in which the building will set on. Cut the form boards to desired length (the size of the concrete block building is up to the builder). Lay out all four corners of the proposed building, measuring each wall and squaring everything as much as possible. Once the form boards are set square, level them with a 4-foot level and secure into place. Add gravel, concrete wire and plastic. Once the forming is ready, figure the amount of concrete by multiplying the length x width x height of pad (4 inches = .33, 6 inches = .5, etc.). Divide that amount by 27, and you have the amount in yards. Once the concrete is poured out, rake it around until it is level with the top of the form boards. Smooth with a concrete finishing float and wait 24 hours. Refer to the drawing for details.

Pull the block from the delivered block cubes and distribute them evenly around the footings. When the block companies deliver, they bring cubes of breeze block. These cubes consist of 80 to 90 blocks that must be broken down into piles of 10 to 12 blocks and stacked about 2 feet away from the concrete footer on which the house will be built.

Mix the mortar according to instructions on the bag, usually 16 shovels of sand per one half bag of mortar. Place two to three shovels of sand and the half bag of mortar in the wheelbarrow. Mix the dry parts together with the mixing hoe and add the rest of the sand. Once all the dry parts are mixed, slowly add water and mix until you have the consistency of cake mix.

Place a few shovels of mortar onto a corner board. Make sure there are four corners of reference to work from and that the walls are square relative to each other. Build at least four corners up about five blocks high. As shown in the picture, use the block trowel to spread the mortar mix in two thick lines about as wide as the breeze block and far enough out to lay three or four blocks long. Make a 90-degree corner. After the first row is down, stagger the next block halfway over the bottom block. Level and plumb your corner walls so they are perfectly straight, square and plumb. Use the thumb jointer to smooth the mud from between the block joints.

Stretch the nylon twine and tie around the line block. Place the line blocks on the corners of the first row of blocks and begin filling in the first course.

Continue until you have run the walls up to the desired height, usually 8 to 10 feet.

Strip the inside walls with 2-by-2-by-8 pine strips. Insulate in between the strips with an R-13 insulation and cover with the desired interior wall material. Reference the attached picture for a general description.

Install an appropriate roof onto the block addition. You will need to determine the roof style and slope based on your existing roof. Once this is done, set the rafters on 24-inch centres, install roof decking, felt paper and desired shingles to finish the addition. Reference the picture for roof detail.


Always have a helper for block stocking and mortar mixing.


Always wear protective gear.

Things You'll Need

  • Wood for concrete pad framing (2 by 4, 2 by 6, 2 by 8 depending on the thickness of pad)
  • Concrete
  • Concrete wire
  • Ploy plastic
  • gravel
  • 8- or 12-inch breeze blocks
  • Type N or Type S mortar
  • Brick sand
  • Round shovel
  • Flat shovel
  • Wheelbarrow
  • 5-gallon bucket
  • Block trowel
  • Thumb jointer
  • Mixing hoe
  • Line blocks
  • Nylon twine
  • 4-foot level
  • Brick hammer
  • Tape measure
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About the Author

Billy McCarley has been freelancing online since April 2009. He has published poetry for Dead Mule, an online literary publication, and holds a Bachelor of Arts degree from the University Of Alabama where he is also a first-year graduate student in history.