RESIDENTIAL CONSTRUCTION

INFORMATION - WHAT IS AN ICF

While there is an increasing number of stay-in place systems available in the United States, they are generally grouped into three different systems.

PHYSICAL DIFFERENCE defining panel, plank, and block systems.

Panel systems are the largest unites, as big as 4 feet by 8 feet. The panels have flat edges and are connected to one another with extra fasteners: i.e.: glue, wire, or plastic channel.

Plank systems include units of long narrow planks of foam (typically 8 feet long and 8 or 12 inches high) held a constant distance apart by steel or plastic ties. The planks have notched, cut or drilled edges that the ties fit into. In addition to spacing the planks, the ties connect each course of planks to the one above and below.

Block systems include units ranging from standard concrete block size (8x16 inches) to a much larger 16 inches high by 4 feet long. Along their edges are teeth or tongues and groves for interlocking; they stack without separate fasteners on the same principle as children’s Lego blocks.

INTERNAL CAVITY DIFFERENCE

There are three distinctive cavity shapes: flat, grid, or post-and-beam. These produce different shapes of concrete beneath the foam, as shown in the following illustrations.

Flat cavities: Produce a concrete wall of constant thickness, just like the conventional poured wall made with wood or metal forms. (forms a monolithic wall of concrete)

Grid cavities are “waffle-like,” both horizontally and vertically. If the forms were stripped away the wall would resemble a breakfast waffle. (forms a monolithic wall of concrete)

Post-and-beam cavities are so named because the cavities filled with concrete are spaced every few feet horizontally and vertically. Some systems cross the horizontal and vertical columns every few feet, while one system has six-inch diameter vertical post every 4 feet with one horizontal beam across the top. (does not form a monolithic wall of concrete)

FASTENING SURFACE DIFFERENCES

Many of the systems have fastening surfaces – constructed of a material other than foam, embedded into the units. These fastening surfaces allow crews to use screws, or possibly a nail to attach materials (i.e.: interior wallboard, trim, exterior siding, etc.) to the wall system as they would with traditional studs.

The above drawings illustrate a panel, plank and block system.

The above drawing illustrates flat, grid and post-and-beam cavities.

Once assembled and intermittently braced, concrete is placed inside the forms to create, in most cases, a monolithic wall of concrete permanently sandwiched within the super-insulating polystyrene forms. This solid structural wall with 2 inches of polystyrene on both sides of 4 to 6 inches of concrete, delivers an energy-efficient wall that would require a 'traditional" method to be built to a value of +R-50!!