Construction> Laying the Block See Also: Windows & Doors | Interior Walls | Ledger Boards/2nd Floor | Bracing Walls | Cabinets/Heavy Fixtures | Plumbing/Electrical Utilities The First Course of Block To Begin:  Snap a line 10 inches from the outside edge of the slab. Mark door openings.  Place corner blocks over the rebar sticking up out of the slab. Align with snapped line.  After all the corners are set, place the blocks along the wall between the corners. Creating Custom Angle Blocks You can easily create custom angle blocks by cutting the blocks and then spot gluing the angled pieces back together. Cutting Blocks Cut length of remaining inside blocks to fit using an electric chain saw (gas saws will get a clogged filter).  Cut blocks as needed for window and door openings.  Remember that all voids will be filled with concrete, so plan ahead for desired concrete placement! Level and Plumb Level and plumb all blocks using rasp and shims if necessary. Alternate method: plumb as you go, level the tops of the walls at the end of the stacking process by snapping a line and cutting off uneven tops, if any. Shims:  Insert shims by tipping the block. Do not hammer the shim in place!  Shims may be removed or cut off once the glue has dried.  Gluing Blocks Spot glue the blocks into place by injecting glue every 6 to 12 inches. Do this by pushing the tip of the glue gun into the area to be glued. You do not need to use too much glue! The glue keeps the block supported during the stacking process and also helps hold the sides together during the pour. Adverse Conditions:  If you are building in a high wind area additional bracing may be required. DO NOT ATTEMPT TO GLUE IN FREEZING OR NEAR FREEZING WEATHER. FREEZING TEMPERATURES WILL CAUSE THE GLUE TO FAIL! DON'T GLUE UNTIL YOU LIKE IT... DON'T POUR UNTIL YOU REALLY REALLY LIKE IT! Rebar placement Cut 1 inch 'wedding rings' from PVC pipe of the appropriate size and place over the rebar sticking up from the slab. Vertical rebar will be dropped into the ring, holding the fixed rebar from the slab together with the new vertical piece. Rebar may also be wire-tied as in traditional installation. Plastic chairs, (pictured here) are no longer recommended.  We have found that they do not work well for this purpose because they restrict the flow of concrete and may cause blockage in the cells.  A #3 rebar "chair" is used to hold the horizontal rebar in place.  As always, place rebar horizontally on supports per your engineer's specifications. The purpose for this support is to retain its position in the center of the grid tube during the pour. The photo shows a scrap piece of #3 rebar being used to span the void of the block, but you could also use a 40D nail or cut your own from very stiff wire. Nails are cheap and don't require cutting, and since you will need a lot of these, you might want to consider using them for this purpose.  Rebar or nails should be no longer than 6 inches. 10” metal supports will cause heat transfer problems affecting heating and cooling in the structure. Occasionally tie the intersections of rebar to maintain their relative positions. Be sure to bend the tie wire against the rebar so as not to obstruct the flow during the pour. Second Course A Checklist  It is best to line up the blocks consistently with one side of the inside wall or outside wall. Make sure that the voids line up. Every hollow void within the wall will become solid concrete. Use this strength accordingly and plan ahead for bolt placements, large open spans, cabinet backing, plumbing access, protected boxes, conduit, etc. Any node may be cut away to allow additional concrete flow. Note: cutting more of the node reduces the integrity of the block making blowouts more likely. Level all blocks, rasp and/or shim if necessary. Check for plumb. Add horizontal rebar as per first course. Continue with this stacking and leveling process, spot gluing as necessary and inserting rebar, with all remaining courses of block. Tip:  2 x 4 Cutting Guide The last course of blocks can be easily leveled or cut at any angle, and any unevenness in the height of the blocks at the top of the wall can be dealt with at the end of the stacking process by simply cutting them straight across.  An easy way to do this final leveling is to use 2 x 4's clamped to the wall as a cutting guide for the chainsaw. Move our vertical braces out of the way if/where needed, while the horizontal cuts are made, then replace them. This makes a very even cut quickly and accurately. For Additional Strength If additional grid strength is needed, the rebar size may be increased, placed on both diagonals, and/or the 'nodes' may be cut away to create a heavier concrete placement as per engineer's specifications.