The requirement for rebar is predicated on site conditions and loads, and may be different from what is delineated below. The following description, however, meets most requirements. All overlaps should be at least 40 times diameter. The typical placement of rebar in our wall system is as follows:
One continuous #5 rebar is suspended a few inches off the bottom of the footing trench.
After a row of stem blocks is set on the unhardened footing, vertical 3" x 30" L-shaped rebars are stabbed into the wet footing at each vertical 6" channel location, that is, 24" on center. They are hooked below to the horizontal #5.
As the wall is being built, one #4 is laid horizontally every 32" in height, that is, in the channel of every second row of blocks. It is not necessary to suspend this rebar in the horizontal grout channel -- this rebar ties the vertical channels together, and laying it in the bottom of the horizontal channels accomplishes this.
A #5 rebar is installed at the nearest horizontal and vertical grout channels surrounding every door and window opening.
#4 vertical rebars are dropped down into each 6" vertical grout channel from the top of the wall, reaching all the way to the footing. The tie wire coils ( Chapter 3, Detail 11 ) are pulled from the outside, tying the verticals dropped from above to the verticals imbedded in the footing.
A continuous horizontal #4 is suspended 2" from the bottom of the bond beam channel in the header blocks at the top of the wall by tying it to the vertical rebars.
A 3" x 30" #4 J-hook is hung from the top horizontal bond beam rebar into every other vertical grout channel, that is, every 48" on center, starting one grout channel from the corners.
If the wall is to receive a top plate, 5/8" x 10" J-bolts are set into the wet grout at every other vertical grout channel, that is, the ones that didn't receive the J-hooks, starting at the corners.
Other Common Rebar Placements
Double header areas usually receive two #5 horizontal rebars.
Ledger bolts for wood floor attachments, second floors, and/or parapet wall ceiling/roof attachments are usually handled as follows: The vertical 2x4s that make up the temporary framework are drilled so that 5/8" x 10" J-bolts are held in the wall in the correct location to later bolt the ledger. The blocks will need to be cut to allow the J-bolts to be suspended into the channels (see below), and the cut needs to be narrower than the width of the 2x4 that will cover the opening; the grout will therefore be contained by the 2x4. If the bolts span a horizontal block seam, one #4 rebar is installed in that seam. If, however, the bolts do not span a block seam, then a #4 rebar is installed in the horizontal channels above and below that area. After grouting and removal of the framework, the threaded ends of the bolts will be left sticking out, ready for the mounting of the ledger.
be narrower than the width of the 2x4 that will cover the opening; the grout will therefore be contained by the 2x4. If the bolts span a horizontal block seam, one #4 rebar is installed in that seam. If, however, the bolts do not span a block seam, then a #4 rebar is installed in the horizontal channels above and below that area. After grouting and removal of the framework, the threaded ends of the bolts will be left sticking out, ready for the mounting of the ledger.