How to Sheath ICF Wall Finishes

You need to sheath the exterior faces of walls made with insulated concrete forms, or ICF, with sheets of oriented strand board if the polystyrene foam ICF formwork blocks are not weather-resistant. Sheathing insulated concrete forms is rare, since most ICF wall manufacturers state that you can attach siding directly to ICF furring strips. Oriented strand boards are 4-foot-by-8-foot sheets of layered wood strands or flakes and binder material glued together. OSB sheets feature marker lines representing 16 and 24 inches on center that builder use as reference points when fastening.

Tape measure
Pencil
Chalk line
Oriented Strand Board Sheathing
2½- or 3-inch #8 galvanized screws
Screw gun
Circular saw
Safety glasses

Instructions

- 1
  Measure down from the top edge of the ICF wall and place a mark along the vertical end of the wall every 48 inches using a tape measure. Repeat the process on the opposite end of the wall. Snap a straight line between the marks with a chalk box, leaving a visible line across the ICF wall.
- 2
  Starting on the right side of the structure, lift a full sheet of sheathing and place it against the ICF wall, with the right edge flush to the outside corner. Check the left edge of the sheathing to see if it is resting on an ICF furring strip. Slide the sheathing to the right until the left edge of the sheet is on center with the nearest ICF furring strip; the right side can hang over the outside edge of the structure.
- 3
  Align the top edge of the sheathing with the snapped line. Ensure that the sheathing's left edge is still centered on the middle of the ICF furring strip. Use a screw gun to thread screws through the sheathing directly into the ICF furring strips near the upper corners to hold the material into place.
- 4
  Thread screws spaced every 6 to 8 inches apart through the sheathing's left- and right-side edges and into the ICF furring strips. Locate the ICF furring strips that line up with the sheathing's 16-inch-on-center marker lines, and thread in additional screws spaced 6 to 8 inches apart.
- 5
  Continue installing full sheets of sheathing, working from left to right, until you reach the opposite side of the wall to complete the first course. Stagger the outside edges of the next course of sheathing by 48 inches and repeat the installation process.
- 6
  Snap vertical lines on the OSB sheathing at the right and left outside edges of the wall and cut any material that hangs beyond the lines with a circular saw to create a neat appearance.

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