Vertical Rebar Placement Strategy
If the “best building practice” is to achieve maximum thermal performance, then staggering the rebar from the exterior side to the interior side of the block works very well.
The photo to the left illustrates that the engineer called for the rebar to be placed every 24” to achieve a symmetrical design. This insulation strategy minimizes and extends the direct thermal path between the exterior and the interior. The result is three layers of insulation 67% of the time and two layers of insulation 33% of the time.
Both of these photos show how the inserts sit slightly below the top of the block. Even though the inserts are 3/8″ taller than the block, they are designed to slide down their respective cells to effectively thermally protect the horizontal mortar joints. The insert tops are even with the block top so the inserts never interfere with horizontal ladder rod. The vertical mortar joints are also protected by the short inserts that overlap from block-to-block.
An 8” Omni Block corner is spotted first at the actual outside corner point of the building. A 12” Omni Block stretcher is then normally placed in both directions from the corner. The Omni corner is placed so that the open ended cells are aligned with the open ended cells of the 12″ stretcher.
The red arrow indicates where a “scab” piece (approximately 3 5/8″ x 7 5/8″ piece of block) is then set in mortar to keep the 8″ block bond continuous.
The hollow cell will have vertical rebar placed in it and grouted.
Typical 12″ corner racked back to allow other masons to fill in the wall to the corner that is also racked back, effectively building speed leads.
The red arrow indicates where a grout cell is located. Rebar is stubbed up from the footing and a vertical rebar will be dropped in the cell before the next grout lift.
Note that mortar is only used under the exterior and interior face shells.
Left photo clearly shows the wall full of insulation, the 8” corner block located at the corner allowing the walls to all stay on block bond.
The insulation inserts slide into their respective cells after each course of block is laid. These 12” block each weighed about 55 lbs.