ICF Framing

 Three layers of blocks on footings

The first row of ICFs are set on the footings and temporarily spot glued. The straight ICF blocks, usually 4 feet long, and the corner blocks all interlock. Each row gets one layer of steel reinforcement. The next row ‘clicks’ (a locking tab or bump – just like ‘leggo blocks’) on top of the row below. A block is generally 16 inches high and we just keep adding layers until we get the desired height. For tall walls or multi-stories the concrete is poured/pumped in every 8 to 10 feet in height. In commercial structures ICF has been used up to 15 stories (higher in the US) and free standing walls can reach 100 ft high (movie theatres for example)

 Filling the steel reinforced walls with

 Filling the steel reinforced walls with

The pumper operator (that’s Casy in this picture) uses a remote control box to move the ‘boom’ and concrete is poured inside the ICFs (Darryl is guiding the hose). At Nutmeg Homes we generally increase the ‘plasticity’ or ‘flowableness’ of the concrete by adding more cement to the mix. 20 mpa is the design minimum and we usually increase this to 28 mpa. Then the concrete is ‘consolidated’ using a concrete vibrator (that’s Kyle with the vibrator – Darryl’s bother) to insure there are no ‘air pockets’ or voids. Because the concrete in an ICF wall is not exposed to air, and is insulated it’s final cure strength can be as much as 150% higher. Traditional formed concrete walls that are ‘stripped’ before 28 days will generally decrease in strength.

Main Floor

 The next floor is build and ready to pour concrete

The main floor walls are just a repeat of the previous step. Vertical steel overlaps connect each pour. Horizontal steel is placed in each layer. The usual rule is to have 10mm rebar every 16 inches vertically and horizontally. This results in an interior steel grid of 1/2 inch reinforcing steel in 16 inch squares throughout the entire structure, typically about 5 tons of steel per home! ICF structures are fairly solid even before the concrete is poured!! Paul and Shareen pictured here are the hands on owners of Nutmeg Homes.

 Scaffold and bracing removed

After pumping in the concrete for the main level, the bracing from the walls, windows, doors, etc. is unscrewed. A typical Nutmeg Home will have about 50 to 60 tonnes of concrete in the walls. This becomes an insulated thermal mass and results in the famous ICF Effect, -low heating energy usage, and very little indoor temperature fluctuation. Wood stud interior walls and roof system usually follow standard frame building practices. Shareen keeps a clean and tidy work site.

Floor Systems

 Joists hangers embedded in ICF wall

Once the basement or crawl space is poured the floor is installed. We like to use a Canadian invented system (ICF’s themselves are a Canadian invention too!) called ‘ICF Connect’ each floor truss is attached to two steel plates that are embedded into the concrete wall (plates are inserted before the concrete is poured). We have found this hanger system to be easier, faster, less expensive and very strong.

There are several options for a floor framing and decking system.

*Engineered joists and plywood or chipboard deck – slightly more expensive than regular lumber but much better
*Regular lumber and plywood or chipboard deck – various grades of wood 2×8, 2×10, etc
*ICF concrete beam and deck such as the Fortruss system (Beaver Plastics/Logix) – this is the Cadillac of floor systems for an ICF wall and can be used as a roof or deck also
*Steel girder and concrete deck such as the Hambro system – works well for very long spans and infloor heat systems

 LiteDeck floor or roof system

Interior Wall Framing

For sound partitions, ‘party walls’ (walls between joined houses or condos), fire walls or bearing walls – ICF walls are perfect (they can be thinner 4 inch walls if desired). Otherwise regular 2 × 4 walls are used for interior framing.

Like a great hat, a roof keeps you dry and warm …

Chapter Two – Part 3 – The Roof