R-Value Concrete Structures, builders of high-quality, energy efficient homes

ICF options

Electrical options

There are several good options for the installation of electrical wires and boxes in ICF homes. There are a couple of poor options as well.

The normal way of installing electrical is to groove the foam, and shove the wires into the groove, foaming them into place. This places them back 2 1/2" from the surface, more than adequate to satisfy residential code requirements.
- A hot knife is probably the most common method for grooving the foam, and is the cleanest, but it is also very slow.
- Faster methods use a router, or even better, an electric chainsaw with a depth stop.
- The boxes are also cut into the foam after the pour is made, and attached to the concrete wall with tapcon screws or ramset nails.
- With the wide availability of flange-mounted electrical boxes, a better option is to use these boxes with the flange screwed to the plastic stud in the ICF wall. This eliminates the need for special tools.
- When an electrical contractor becomes experienced with this method, it is very quick, and installation costs will be comparable to framed construction.
Plasticlock electrical boxes are the only box UL listed for use in ICF walls. They are pre-installed by the ICF contractor as the walls are being constructed, and 1/2" or 3/4" conduit is attached and run to interior walls or up to the top plate. Then after the pour, wire is fished through by the electrical contractor.
- This method is slower for the ICF installer, but quicker for the electrical contractor.
- This is a more costly method, but is much cleaner.
- Using conduit allows wires to be upgraded later with minimal hassle.
- Commercial construction requires that wiring be installed in conduit.
E-Channel by Solcraft PDC is a 2 1/2" deep chase that is installed prior to the pouring the walls. The wiring or conduit can then be installed into the chase.
- This is a newer system and I have not yet tried it.

Roof options

There are a couple of options for roofing materials, as well as methods of attachment.

Wood truss roofs
- For standard attachment, bolt a treated plate to the top of the wall, and then the trusses are clipped and nailed to the wall like in framed construction. This is the least expensive option.
- Hurricane straps hold each truss individually to the concrete wall, and greatly increase the overall strength of the home. This is still a relatively inexpensive option, but more than the standard.
SIP (Structural Insulated Panel) roofs
- For standard attachment, bolt a treated plate to the top of the wall, and then the SIP's are attached to the plate like in framed construction.
- A study was recently completed regarding the best way to attach SIP roofs to ICF walls. Download it here.
Concrete roofs are best used on 5/12 and lower pitches. They are ideal for the Frank Lloyd Wright style of home with multiple flat roofs. The more complex and sloped the roof, the more cost.
- Concrete roofs greatly increase the strength of the home, as well as energy efficiency and noise reduction.
- Steel pour over systems use a light gauge metal deck supported by steel joists that concrete is poured over. Insulation must be added afterward.
- ICF pourover systems use Lite-Deck or a similar product to form the roofs, insulation, and furring.

Reinforcement

Standard rebar reinforcement is placed in accordance with local codes as well as the manufacturer's recommendations.
Helix steel fibers are not your usual steel fiber. These twisted fibers are mixed into the concrete and provide the structural strength to replace most of the rebar in an ICF wall.
- In many instances Helix fibers reduce cost by reducing the time spent on the jobsite.
- They promote better strength becasue they are throughout the entire thickness of the concrete, rather than in one spot only.
- Helix steel fibers do not add to the congestion in an ICF wall, promoting better concrete flow and easier filling and consolidation of the wall.

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