Benefits of ICF Construction

 

ENERGY EFFICIENCY

                       

                   In my opinion, energy efficiency is the most important benefit to ICF homes, with strength running a very close second.  Energy savings have been recorded to range 30-90% compared to a wood framed home, depending on the climate.  In an ICF home, the insulation is provided by the polystyrene forms, but there is more involved in the energy efficiency of ICF homes than simply the R-value of their insulation.  While polystyrene is an excellent insulator (used in commercial refrigerators and freezers), near zero air infiltration, continuous insulation, and the thermal inertia/mass of the concrete all play important roles in the energy efficiency of ICF homes.

                   An ICF home is extremely air tight.  No joints exist between walls, or between walls and floors.  This prevents conditioned air from leaking from the interior to the exterior and, likewise, prevents unconditioned air from penetrating from the exterior to the interior.  The fact that ICF homes experience much less air infiltration than conventionally built homes computes directly into energy savings for the ICF homeowner.

                   Another key benefit of ICF walls is the consistency of insulation throughout the wall system.  In wood frame walls, insulation is only placed in the voids or cavities formed between the studs.  Plate and stud areas are solid wood or steel,  which allows heat and cold to be conducted more easily.  Because the insulation is broken at the studs in wood frame construction, by placing R-19 insulation in your wood framed walls, you do not end up with an R-19 wall.  Your insulation is rated at R-19 but your total wall will only perform at about an R-11 or 12.  ICF homes, on the other hand, utilize continuous and consistent polystyrene insulation with no breaks, voids, or cavities.  Although the polystyrene insulation used in the majority of ICF homes has an insulating value of R-22, in most climates the actual effective insulating value of the entire ICF wall is between R-30 and R-50 as a result of the unbroken continuous insulation, near zero air infiltration, and the thermal mass of the concrete.

                   CTL labs in Kentucky performed a series of “hot box” testing on ICF wall assemblies.  This method was used because hot box testing is a far more accurate analysis of heat loss than simple calculated R-Values.  Although the calculated or “static” R-Value of most ICF forms is R-22, the certified hot box testing of ICF walls resulted in the following equivalent R-Values for the wall assemblies, at the locations shown, based on an 1800 square foot ranch home with 20% glazing (glass) area:

                                                                                                          Los Angeles – greater than R50

                                                                                                          New York City – R-42

                                                                                                          Minneapolis, MN – R-28.7

                   Regardless of how you look at it, ICF homes are simply much more energy efficient than homes built by conventional methods.  It is guaranteed that an ICF home will save you a substantial amount of money in heating and cooling costs versus a conventionally constructed home.  Furthermore, because ICF homes are so much more efficient, HVAC systems are actually DOWNSIZED from what would be required in a conventionally constructed home of the same size.  There is also less wear and tear on the HVAC systems installed in ICF homes because of the fact that they cycle on and off much less frequently.

 

STRENGTH

                       

                   As I stated earlier, I consider strength to run a close second to energy efficiency when it comes to the benefits of ICF homes over conventionally constructed homes.  Most people, however, consider strength to be the most important benefit of ICF homes, which is undoubtedly the reason that you will find more ICF homes on coastal areas prone to hurricanes than other areas of the country.  The raw strength and integrity of steel reinforced concrete is unrivaled as a practical building material.  That is a simple plain fact.  ICF homes have been tested and proven to withstand sustained winds in excess of 200 mph and the flying debris from the force of an F-5 tornado.  The true stories of ICF homes surviving various disasters while conventional homes around them are destroyed are far too numerous to tell here, but I will share a couple with you.

                   During the aftermath of Hurricane Katrina, the story of Scott Sundberg stands out as one of my most memorable.  Mr. Sundberg is an engineer by trade and decided to build his dream home on the Mississippi Gulf Coast.  To save money, he decided to build his home himself and, being an engineer, decided to build it using ICF construction.  Although his home was not yet completed at the time the hurricane hit, the exterior walls were complete.  After the storm, there was not a house in sight of Scott’s whereas before the storm he had neighbors everywhere.  The homes around Scott’s on all sides were built using conventional methods and not one of them withstood the storm.  Scott Sundberg’s ICF home, however, not only weathered the storm but is still there today.

                   Another story that comes to mind happened in Cape Coral, which is in Southwest Florida.  I forget her name, but the owner of this particular ICF home was asleep in her bed when she heard a slight thud.  Thinking that something had fallen off of a shelf or something of that nature, she got out of bed to investigate.  Upon entering her living room, she was surprised to find bright lights shining through her windows.  The thud that she had heard was actually a Pontiac Firebird crashing into her home at over 90 miles per hour.  Because of the level of sound insulation provided by ICF homes, she had no idea that a car had actually hit her home head on.  While the car was completely destroyed, only a small area of Stucco and a little polystyrene was damaged on her home.  There was not even one hairline crack in the concrete.

                   These are just a couple of the many testaments to the strength of ICF homes, but there are countless more such as an ICF home in Wisconsin that withstood a direct hit from a tornado while all other homes around it were completely destroyed.  I could literally go on for days about the unrivaled strength of ICF homes, but instead I will leave you with just this – if you ever have the chance to meet a person who has weathered a hurricane or tornado in and ICF home, I guarantee you that they will tell you that they would never consider living in any type of home except an ICF home.

 

UNIFIED SLAB/WALL SYSTEM

                       

                   In ICF construction, the exterior walls and slab/foundation of the home are one unified unit.  Rebar (steel reinforcing bars) are not only placed throughout the slab, but from the slab into the walls and throughout the walls.  The rebar and concrete connect everything together, forming a sort of reinforced concrete box or bunker.  This feature of ICF homes greatly improves the strength and stability of both the walls and the slab.

                   Imagine that you have a flat piece of cardboard in your hands.  Certainly you can see that you would be able to bend the flat cardboard with very little effort at all.  Now imagine that you have a small cardboard box in your hands.  It would be more difficult to bend the box because the sides and the bottom work in unison to strengthen the entire object.

                   In areas with soil prone to shifting, the exterior walls of an ICF home actually reinforce the slab.  In a home built by conventional means, when the soil beneath the slab shifts excessively, the slab cracks.  Once the slab cracks and separates, so do the walls of the conventionally constructed home.  In an ICF home, when the soil beneath the slab shifts, the slab remains intact.  There is ICF engineering that states that you could completely dig all of the soil from under the slab of 1/3 of an ICF home and the structure would remain intact – slab and walls.  Now, I have never tried this nor have I seen it done, but the engineers are saying that you could basically pick up an ICF home and place it on the edge of a cliff with 1/3 of the slab hanging out over the edge and the home would be fine.  Try that with a conventionally constructed home and I am certain that you would be left with nothing but a pile of lumber.

 

SUPERIOR FIRE RESISTANCE

                       

                   This is a fairly simple concept to understand.  Wood burns and concrete does not – it is really that simple. 

 

SOUND INSULATION

                       

                   The vast majority of people who own ICF homes will tell you that their homes just “feel” more secure.  Probably the main contributing factor to the ICF home’s “feeling” of security has to do with its ability to isolate the home from outside noise.  This not only creates a “feeling” of security, but a more peaceful and comfortable atmosphere in general.

                   STC (Sound Transmission Class) rating is a single number quantifier used to rate walls, doors, and other partitions for their effectiveness in preventing sound transmission.  Basically, a higher STC rating indicates a more efficient sound absorption characteristic.  While the typical wood framed home has an STC rating of 33, ICF homes consistently achieve STC ratings of 55 and higher.

                  STC ratings, however, can be misleading because they are based on a logarithmic scale.  Therefore, an STC rating of 50 is not actually one better than an STC rating of 49.  Actually, and STC rating of 50 should be deemed twice as effective as an STC rating of 49.  Furthermore, the actual behavior of two partitions with the same STC rating can be dramatically different, as the STC rating is weighted in favor of the part of the sound spectrum that represents the human voice.  In the real world environment, one of the most annoying transmitted sounds between dwellings tends to be the bass in music, a part of the sound spectrum far removed from the human voice range.  This in mind, an ICF wall with an STC rating of 50 will perform much better than a wood framed wall with the same STC rating.  Same STC rating, but still the ICF wall is more effective in stopping the transmission of annoying sound.

                   Now let me give you a real world example of the ICF home’s ability to stop the transmission of annoying noises from my personal experience.  I have a close friend who lives in an ICF home just outside of Starkville.  He has (actually “had” but that is another story in itself) several geese as pets that just roam about in his yard.  If the fact that he has (actually had) geese roaming around his yard seems odd to you, it really is not as he lives outside of town and has the tendency to be a bit unique as well.  At any rate, if you’ve ever been around geese you know that they “honk” at people and it is a very annoying sound.  Well, these geese were no exception and every single time I pulled into the driveway these geese would honk like crazy until I entered the house.  This is something that is quite honestly very annoying.  One day I was at his home and one of his daughters who had spent the night with a friend returned home.  It occurred to me that I had not heard the geese announcing her arrival so I went outside to investigate.  As soon as I walked out the door, I was assaulted by a very annoying group of geese “honking” at me.  The second that I went back inside, however, the geese were silenced.  Looking out the window I could see that the geese were still going at it, I just couldn’t hear them through the ICF walls.

 

AIR TRANSFER RATE

                       

                   As I stated earlier, the fact that ICF homes experience a lower interior to exterior (and vice versa) air transfer rate than conventionally constructed homes is an energy efficiency plus, but it doesn’t stop there.  There are many, many more benefits as a result of a lower air transfer rate.

 

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