Every block wall-regardless of height or length-should be placed on a secure footing of poured concrete. A block barbecue grill or outdoor fireplace requires a large concrete pad as a footing. The footing must extend down beyond the frost line to prevent heaving in the winter.

Any building has to have a permit and that requires a drawing or plan. It is important to identify all the dimensions for the wall. The walls are to be laid out the same as on the floor plan, with all measurements followed exactly. The openings for doors and windows must be placed exactly. It is important that the corners be set on the foundation exactly as given on the detail drawing on the foundation plan. All 8″ blocks-the standard unit-are actually 7-5/8″ in width. This allows for the thickness of the mortar on the finished job.

Building exact corners is the most important construction of a masonry
wall as corners will guide the building of the rest of the wall. A corner pole will make the job easier. A corner pole is any type of post which can be braced into a true vertical position and which will hold a taut mason’s line without bending. Two such poles are set up, one on each corner, with the mason’s line stretched between them. Corner poles for block walls should be marked every 4 to 8 inches, depending on how high the material is with which you are building the wall. Such marks must be absolutely level when the mason’s line is stretched between them.

Before starting to lay the blocks, drive stakes into the ground and build a form at each corner. These stakes and forms can be made from scrap pieces of wood used on the job. Locate the exact corner by stretching lines from one corner form to the other. The exact corner will be the point at which the two lines cross. Drop a plumb bob down from each line, both at the corner point where the lines cross and at positions about 2′ out in each direction.

Make sure the mason’s line is stretched taut and attached to the line holder at each corner. The line should be no further away than 1/8″ from the face of the wall, and when the block is set into the mortar to form a 3/8″ mortar joint, the top of the block should be even with top of the mason’s line. Allowing the block to touch the mason’s line is called “crowding the line” and could cause a bulge in the wall.

Probably nothing is more confusing to the lay mason than mortar mixes. And it’s not hard to see why: There are three different kinds of mortar available for brick- and block-work: cement-lime mortar, masonry cement mortar, and the awkwardly named mortar cement mortar.

Learn more about The Barrie Home Inspector for guaranteed Peace of Mind. For a ProfessionalCertified Home Inspections in Barrie, Orillia and Alliston to protect your Real Estate needs.