Setting the First Few Courses Review

This lesson covers the basic procedure for setting the first four courses of ICF block, along with the materials and preparation you need.

Proper preparation and material staging can help ensure your build stays efficient and clean. Make sure the footing or slab is clean and ready, walk the foundation to locate door and window openings, and confirm the layout is square with chalk lines snapped. Stage materials inside the work area to save time—if you’re only stacking a few courses before pouring a basement floor, stage just what you’ll use immediately; otherwise include bracing and alignment systems, forms, foam, and rebar. Keep all material at least six feet back from the future wall so the bracing system can be installed later, and understand your reinforcement schedule and any specialty or half-height blocks before you start. Verify that vertical rebar from the footing is high enough to meet non-contact lap requirements, and drop PVC rings (about 1¼–1½ inch diameter, ½–⅝ inch long) over all vertical pins.

Next, start forming walls by stacking block. Start stacking in a corner and work in one direction toward a common seam or an opening. Place horizontal rebar securely in the built-in webbing as specified, and on each new course reverse or flip the corner blocks to create an offset running bond—this locks the blocks together and keeps the webs aligned. Use the molded cut lines and one-inch repeating pattern when cutting; keep cuts square and clean, and reuse any cut block with at least one web, ideally near openings.

Ensuring your walls are level early in the stacking process will help keep your build efficient and prevent headaches later on in construction. After two courses are laid around the structure, shim and trim to level—getting it level now keeps the whole build level. Once level, spot-glue every 18–24 inches, using foam sparingly; too much adhesive lifts the wall out of level. After more block is stacked and the alignment system is attached, you can run a full bead of foam.

As you stack your walls, it’s important to note the location of vertical seams and ensure they are sufficiently strapped. Vertical seams where blocks meet from opposing corners should have at least a 12-inch offset and sit 16 inches (two webs) from a corner. If a seam is closer than 16 inches, strap both sides of the wall—use 1×3 strips from 2-by or larger lumber, or flexible Masonite for field-cut radius—extending at least two webs on either side of the seam. Pre-mark openings, centerlines, penetrations, and distances from corners on the block before cutting to keep everything correctly sized and placed.