This page describes the scope of the system being analyzed: Insulated Concrete Forms - Foam. Please click on any of the links below to jump to that part of the page.
What are Insulated Concrete Forms? How does it work? What needs does it meet? What advantages does it have for the Radford area? This section provides a functional description of the special foam Insulated Concrete Forms.
Insulated Concrete Forms or ICFs are available in two materials, expanded or extruded polystyrene foam forms and composite material forms. (Composite ICFs Info) The forms, made of foam insulation are either pre-formed interlocking blocks or separate panels connected with plastic or metal ties. The left-in-place forms not only provide a continuous insulation and sound barrier, but also provides a backing for drywall on the inside, and stucco, lap siding or brick on the outside. These ties are also designed to provide perfect inter-locking notches for rebar. (See Fig. 1) This allows for easier more efficient installation of rebar and conduits. The foam allows for electrical and other conduits to be cut out with a simple hot knife.
Fig. 1
These building "blocks" are used for both commercial and residential however, the advancement of the product has been for residential purposes. This system is especially practical for areas that have a high degree of seasonal temperature change. Why? These systems ability to save energy is second to none, the polystyrene insulation is virtually seamless when correctly installed allowing for nearly no temperature transfer. And there is no need to be concerned with the environment becuase you can rest assured that the polystyrene is environmentally safe because it is nontoxic, recyclable, and does not break down or support moisture.
Insulated concrete forms are relatively new to the construction industry, and as such there are many different ICF wall types. Products are differentiated based on the shape of concrete sections and the type of form. ICF is further differentiated by R-values, foam types and other features.
Form Types
The basic three form types used in the construction industry are panel, plank, and block. ICF panels are usually 4' x 8' and are attached to each other by plastic ties or glue and are the most commonly used. Planks are stacked and connected using ties and block forms are the smallest and can be cut and shaped to specifications.
Concrete Configuration
Depending on the manufacturer, the concrete configuration systems within a specific form type can differ. Concrete configuration refers to the way the concrete spreads out through the form and what shape it takes within the wall. The most commonly used concrete configurations are the screen grid/post-beam, waffle grid, and flat-wall systems. The screen grid/post-beam system forms distinct horizontal and vertical columns of concrete while the waffle grid makes concrete configure much like that of a waffle. The flat-wall system is probably the most popular of these three and involves even pouring of concrete inside the wall. A less common configuration involves tilt-up construction where the concrete is poured on the ground and lifted into place.
Materials and Production/Assembly Approaches
Manufacturers produce ICF in a number of ways. Most ICF are made of plastic foam, usually expanded polystyrene (EPS) or extruded polystyrene (XPS), although other materials are sometimes used. However, most manufacturers use EPS in their products. ICF are also produced at different R-values, usually in the range of R-17 to R-26 though even higher R-values exist. Most ICF are filled with concrete on site; however, Apex Blocks is a mentionable manufacturer because they use recycled EPS in their blocks and also ship their product with concrete already set. It is also worth to mention that some manufacturers sell ICF forms that are made for curved and angled walls.
The following Johari Window describes which components will be included and excluded for analyzing functional equivalency between ICF-Foam and OVE wall systems.
There are numerous manufacturers for ICF's all over the United States and Canada. Below are some of the major manufacturers of this system and a description of what products they have to offer.
Concrete- is protected from freezing and drying too rapidly by the insulation of the polystyrene. The form work provides protection to the concrete from moisture which intern help to minimize the risk of expansion and contraction. If the insulated concrete form work were to fail then the concrete inside would be greatly affected and could lead to a weak and non supportive wall.
Interior finishes- Moisture can be a problem with interior finishes. Since there is no space between the gypsum board and the polystyrene moisture could become a problem if present. The gypsum board would absorb more water than the polystyrene which would cause it to become weak and very easy to damage. It could also aid in mold growing depending on what type of gypsum board is used.
Electrical- The electrical is wired differently in insulated concrete from construction. A hot knife is used to cut a groove in the polystyrene where the wires are fitted in. If the insulated concrete form work was to fail and let in moisture, it could potentially short out the whole electrical system. The polystyrene is so compact that if water/ moisture were to get in it has no place to go so it would just sit in the grooves where the wires run.
HVAC- Depends on the insulated concrete forms to work properly in order for it to work most efficiently. If the ICF's fail then the HVAC will have to work to make up for the poor insulation which will cost the owner extra money.
ICFs are used both in residential and commercial construction; but residential construction has seen the use of ICFs as the primary building material across the country because of their superior energy performance and high sound absorption as compared to regular wood framed structures.
On an average, the cost of construction using ICFs is around two to five percent more than wood framed construction. This includes the cost of installation labor, reinforcement, bracing and concrete placement. The cost of ICF material ranges from about $1.75 per square foot to about $3.50 per square foot.
However, the energy savings of an ICF home usually result in lower cost for utilities from Day 1 compared to most conventional construction. Homes built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses. Consequently, HVAC systems are also downsized.
ICF walls are designed as reinforced concrete, having high wind and seismic resistance. The walls of a properly-constructed ICF home are resistant to loads imposed by high winds, and can be designed for all seismic zones.
ICFs can withstand extreme weather conditions because the insulating forms protect the concrete from freezing and rapid drying. In extremely cold conditions, only insulating blankets are required to protect the top of the form; while plastic sheeting is required to cover the form top as evaporation can be a major issue in very hot weather conditions.
Also, the moisture resistant qualities and safety from termites and pests make ICFs more durable than regular wood framed construction.
Additionally, ICF homes have a proven track record of withstanding the ravages of hurricanes, tornadoes and fires, when all the stick-build houses around them are in ruins.
