Frequently Asked Questions
What Is ICF?
ICF stands for Insulating Concrete Forms. They are comprised of two pieces of EPS foam and a plastic tie often referred to a as webs. The webs hold the foam apart to forma a core where concrete will be added when the construction is complete.
ICFs are a wall system comprised of concrete and a form that remains in place after the concrete is poured and cured. This creates a very strong, energy efficient, stable wall that provides safety, security, comfort, and less maintenance over time for the building occupants.
Cost Comparison Of ICF To Wood
This is a common question that is not easy to answer. Ultimately people are trying to determine what this will do to the construction budget for the structure. The trouble is this is like a sedan with a high-performance sports car. They don’t perform or operate the same and the cost difference shows this.
They are looking at comparing wall systems, wood framed and ICF. The wall system is one component of the whole house. ICF when compared to wood wall systems is not cheaper but it affords benefits that cannot be accomplished by wood. If we were to adjust the wood walls to make then perform like the ICF, the cost of the wood wall could triple and it will still not perform as well as the ICF.
Generally, folks are trying to maximize the amount of home they can squeeze out of the budget. Often, we discuss the difference between construction costs and operation costs. Folks asking this question are focused on construction costs only. The rule of thumb is pay now or pay alter. In our case the balance is the same. Typically, spending more on construction to get better quality nets a savings in operations later. A home developer or spec home builder will focus on construction costs because he is not going to operate the home. When you are considering the balance between today’s budget and tomorrow’s, a savvy homeowner will realize the operation costs are present every year you own the home. Buying an older home can cause these operation costs to increase. The benefits of ICF allow for lower operating costs overall. Keep in mind that even after the home is paid off, this benefit continues.
The conversation about price is simply very similar to quantity over quality. They will typically not pursue the ICF option since it can add up to 10% to the total cost of the home when compared to traditional wood framed construction. Let me stress this is on the bottom line cost or the mortgage. This will amount a small amount each month as the cost is amortized over the term of the loan. The savings on the operation and maintenance of the home offsets these added costs each year.
Ultimately, a person interested in ICF is looking for one or more of the benefits ICF provides. The cost for modifying a wood structure to perform with the same benefits of ICF is hard to calcite since some of the benefits are not able to be achieved. With ICF, if you are attracted to one of the benefits, you get the others for no extra cost!
Construction Speed
Speed of construction is a benefit of ICF. In colder weather climates the walls can be poured in winter time due to the foam preventing the Concrete from freezing. when compared to other construction methods ICF can save steps and labor as the wall system is 3 components in one product. There is the structure, insulation, and framing in one step. Some examples to illustrate the point, if you are building with CMU (cinder block) to place sheet rock or most other finishes, a framing member will need to be added. ICF has the members already.
What Do You Do About The Lack Of Air Flow
Part of the energy efficiency of an ICF house is no air leakage. Since the building will be so tight, care should be taken in the design and selection of the HVAC systems to provide good indoor air quality. Controlling the humidity and moisture is critical. The size of the unit will need to be reduced when compared to a traditional building. An oversized cooling system will short cycle and add humidity tot eh space that can lead to mold and mildew problems. All wet areas should have an exhaust fan to remove moisture to the outside. You should consider adding filtered makeup air and, in some areas, dehumidifier may be required. A good HVAC contractor is a must to have on your team.
Expected R Value
R value is the measure of how well the product resists heat flow. Since we do not have a measuring device that determines this r value it is calculated through laboratory testing. The industry uses it like a barometer to give some semblance of comparison and quantifying the amount of certain material to achieve an equal resistance to heat transfers. When comparing ICF and other systems there are several other factors to consider. The short answer is ICF provides a more consistent interior temperature by reducing heat radiation, conduction and convection on the exterior walls. To help you get an idea of what the potential could consider the walls can provide and equivalent of R50 when constructed correctly.
How Do You Hang Into Your Finishes
The foam is held apart by the web, which also doubles as attachment points for all types of finishes. Essentially any finish on a traditional building can be applied to ICF.
How Do You Hang Pictures?
Typically Picture hangers are using the gypsum to carry the load. So, this will not change. Buildblock feature a connection point every 6 inches that provide 150 lb. of pull out strength and ‘hardpoints’ that can provide 400 lbs. of pullout strength. In short, you have several options to hang heavy items that cannot typically be installed in wood framed construction.
What If You Have To Add Plumbing Or Electrical Later?
Remodeling gin ICF is possible and simple for those that are familiar with it. Most builders will not know what to do. As an ICF expert, contact us for more information or if you have need to remodel your ICF house.
Finished Wall Thickness
ICF walls are thicker than traditional walls. ICFs are often referred to by the width of the core of concrete. Always make sure you are on the same page with those you talk to by confirming the thickness of the foam on the block. BuildBlock feature two pieces of expanded polystyrene (EPS) that are 2’1/2 inches thick each for a total of 5 inches of EPS. These 5 inches will be added to the core of concrete for the total wall width ranging from 9 up to 29 inches.
Please note, the minimum thickness is 9 inches but most folks us the 6” block which is 11 inches overall.
Does It Change Slab Requirements
Adjustments are often made to the slab to maintain the interior dimensions. This is especially true when converting a structure to ICF from another method. The overall slab design should not need to change too much, however always consult a geotechnical or structural engineer since soils are different in all places.
Does It Require Anything Special To Run Electrical Or Plumbing
No. Running electrical and plumbing is easy. The most difficult thing is the plumber and electrician will need to get used to a different method of installation. We have had several experienced contractors tell us it is easier to install.
Requirements For Water Proofing
If you are planning on using ICF for a basement you need to apply some waterproofing to the foam that is compatible with EPS. We can recommend contractors or install this for you. Above grade walls do not need any additional waterproofing, or air barriers except at window and door openings. We can assist you with the details of your project.
Can I Have A Fireplace?
Absolutely! Fireplaces can be included. Some considerations of the quality and type of fireplace should be considered to maintain the efficiency of the home.
What Type Of Windows Should I Get?
We strongly recommend you get good quality energy efficient windows. You will have a high-performance wall and the window will be the weak link in that. Typically, you want to look at the performance of the window comparing the U factor and solar heat gain coefficient values. these are the values that show the performance of the windows. The closer the values are to zero the better the performance. TO assist in selecting windows we recommend you look at the window selector tool at https://efficientwindows.org/window-selection-tool/
Fire Protection Ability
ICF can be used as a fire wall with a 4-hour fire rating. The materials in ICF do not contribute to the fire. Extensive fire testing has been done on ICF walls. A sample assembly of a six-inch wall was placed in a furnace at 1500 degrees Fahrenheit. It was then cooled quickly with a 2-water hose. It was load tested and passed with no deflection or damage. The report is here https://buildblock.com/technical-support/product-testing/buildblock-firewall-test/
Here is some additional info https://buildblock.com/insulating-concrete-forms-icfs/icf-disaster-resistant/fire-resistant/