When one takes a look at the five-in-one construction components provided by insulating concrete form (ICF) construction, and combine that with the major performance benefits of building with ICFs, it becomes evident that ICF construction is a better way to build. Here is the breakdown:
Five-in-One Construction
The 5-in-1 wall assembly provided by insulating concrete forms means you complete five steps – steel reinforced concrete walls, furring attachment, insulation, air barrier and vapor barrier – all at the same time. Any other wall system would require additional material (and labor) added to the wall to achieve what one inherently achieves with the ICF wall. For example, a wood or metal framed building would still need to be insulated, as well as have the air and vapor barriers added to the wall, and a comparable masonry wall would need to be furred out and insulated.
Major Performance Benefits
R-Value
Typically ICFs have a steady state actual R-Value of R-22. While this does not include the thermal mass and lower infiltration rate effects that add to the overall energy performance, it is still a higher R-Value than the other standard wall assemblies. A wood or metal stud wall will typically be insulated with an R-13 to R-19, and an un-insulated masonry wall will have an approximate R-Value of R-2.
Combine the higher R-Value with the thermal mass and lower air infiltration rates, and a building with exterior ICF walls will significantly lower the heating and cooling costs.
Strength
There are a couple of different ways to look at the strength of a wall, such as lateral and axial capacity.
Example: If you take a 10 foot wall, braced at the top and bottom, and apply a uniform 25 psf lateral load to the wall, the axial load capacity of an 11 inch iForm from Reward Wall Systems is 22,000 pounds per foot, and the 13 inch iForm has a capacity of 50,000 pounds per foot. A 2 x 4 wood stud wall with 16 inch spacing has a capacity of 425 pounds per foot. A 2 x 6 wood stud wall with 16 inch spacing has a capacity of 3,220 pounds per foot. A 3 5/8 inch and 6 inch 18 gauge metal stud wall has capacities of 500 and 1,775 pounds per foot respectively.
Looking at just the lateral load capacity, a 10 foot tall 11-inch iForm wall has a 65 psf capacity without any axial load applied. In comparison, a 2 x 4 wall has a lateral capacity of 37.5 psf.
Fire Resistance Ratings
Depending upon which ICF wall assembly is used for the building, it will provide a two to four hour fire resistance rating. In comparison, a wood or metal stud wall typically provides a 30 minute to one hour fire rating (depending upon the wall assembly and gypsum board), whereas a partially grouted masonry wall will provide around a two hour fire rating.
Sound STC Ratings
Sound ratings provided by the base ICF walls also out perform other wall types. A Reward ICF wall with gypsum board on each side will have an STC rating of 44 for the 9 inch iForm and 51 and greater for the 11, 13 and 15 inch iForm. A wood frame cavity wall will have STC values in the low to mid 30s, and a metal stud wall will lie in the mid to upper 40s. One thing to keep in mind is that the difference of sound ratings is exponential when it comes to actual sound transfer.
In directly comparing wall assemblies with the ICF system, it is easy to see that ICF construction not only inherently provides more, but also outperforms. When you add five-in-one construction to the comparative performance benefits, the already impressive ICF wall becomes even more attractive.