Exploding the Myths of Insulating Concrete Form Construction Technology
The insulating concrete forms (ICF) industry is rampant with inaccurate information. Some have been passed along by industry members, while others represent simple misunderstandings about the technology. Most of these misstatements are made by persons that simply without the appropriate knowledge behind the information. The toughest part of researching ICFs is not finding the information, but sorting by all of the inaccurate information.
Virtually every aspect of the ICF industry is affected by misstated information, but the most shared issues include discussions of R-Value, waterproofing, and termites and bugs. R-value statements range from R-18 to R-50+. To explode this myth and get a clearer understanding of this myth, you will need a firm understanding of R-value and the difference between PERFORMANCE and TRUE R-values.
Myth 1: R-Value
An R-value is the measure of resistance (R) of heat flow. Heat flow can be resisted by insulating materials such as plastic foams or mineral fibers, or can be slowed by enormous thick materials such as thick masonry or concrete. The larger the R-value, the greater the resistance and the better the insulating value.
All building materials move heat to some degree. Heat move can be measured by any of the following: 1. Conductivity (k); 2. Conductance (c); 3. Transmittance (U); 4. Resistance (R).
The ability of thick materials to retard heat flow depends on their ability to store heat and is measured by specific heat and heat capacity. (BTU per lb. Per degree F; Density lb. Per cu.ft.; Heat Capacity BTU per cu.ft. per degree F)
When it comes to stating R-values in residential construction, the insulation values applied to a wall or ceiling typically refer to the R-value of the insulation material that is installed, not of the wall or ceiling assembly. For example, when a 2×4 stud wall is insulated with R-11 batt kind insulation, the builder states that the wall is an R-11. This is not totally accurate and is NOT TRUE since approximately 20% of the wall is not insulated at all. The wood framing and sheathing do have an R-value, but for the sake of making insulation claims, they add very little. The real R-value or PERFORMANCE R-value ends up between R-3 and R-9. Add to this, the fact that the wall is complete of penetrations, such as electrical outlets etc. and the fact that the wall itself is basically hollow in character. This additional thought leads to another discussion on air leakage by the wall.
With ICF technology, the TRUE insulation value of the wall is that of the Expanded Polystyrene (EPS) since the EPS provides a continuous insulation plane from the footing to the top plate. The insulation value of the EPS is determined by the density and thickness of the material. Some ICF systems have EPS that is of differing thickness (waffle and post and beam systems) that typically average the thickness of the foam. This is, in my opinion, not an accurate measurement since a bucket with a hole in the bottom doesn’t carry as much water as a substantial bucket with a hole at the top. Most ICFs utilize EPS foam that has a density of approximately 1.5 lbs pcf to 2.0 lbs pcf. The insulation values differ only slightly in that range and depending on the testing laboratory, provide R-values between R-4 and R-4.5 per inch of EPS thickness.
The claim that ICF walls are an R-50 started a few years ago after the Insulating Concrete Form Association (ICFA) and several members commissioned CTL Laboratories in Chicago to perform some R-value testing and examination. The summary of the report basically said that depending on the climate zone, the PERFORMANCE R-values for ICF technology is as high as an R-52 when COMPARED to typical wood frame and batt construction. In order to make the comparison correct, one must insure that the comparison is being done vs. the different to ICF on the particular project. On average, the performance R-value is much less than the claimed R-50. Research by the consumer must be done to clarify the comparison for the actual project. In short, ICF will PERFORM at an R-50, but that statement is not accurate as far as an insulation value goes.
For more information on insulation values, green building, and energy efficient building, try these websites for research:Energy Star Program, Concrete Homes. Do a Google search to find others many others. It is worth noting that there are many options for research on the internet and that I neither own nor control any of the suggested research links listed in this article.
Myth 2: Waterproofing
Yes, below grade concrete construction should always be waterproofed and this includes ICF technology. Three options include: dimpled membrane, peel and stick membrane, and roll-on/spray-on products. In some jurisdictions in the US, a combination of dimpled membrane and peel and stick membrane or roll-on/spray-on products must be used to meet local building codes. It is best to consult your local building code officials and your local ICF supplier to ensure that you meet the minimum code requirements and use only products that are compatible with EPS.
Myth 3: Termites and Bugs
According to the ICFA, the International Residential Code has provisions in the IRC to allow for foam to be used below-grade. The IRC stipulates in addition to chemical soil treatment, foam can be used below-grade on the exterior of the wall if one of the following requirements is met:
- All interior partition walls and roof trusses are built of a non-combustible material such as steel studs or pressure treated lumber.
- An approved method for protecting the foam plastic and structure is used.
Polyguard Underseal(TM) XT Waterproofing Membranes has an evaluation report that shows they are an approved method for protecting foam from termites below-grade. Checkout the Polyguard website for additional Polyguard information. Tip, you may want to install an aluminum termination bar along the top edge (AKA: termite stop-ant stop). One assistance, besides stopping insects, is that the termination bar helps out with screeding stucco, etc. over the foam which you will need to protect the exposed area of foam. Also, don’t run your siding down to the grade. This is just another shortcut for ants, termites, and other insects to get up the wall and start nesting behind your siding.
Remember, these insects don’t eat the foam, but they can burrow by it, especially in search of food. Eliminate the food source and eliminate the problem. Wood products can be totally replaced in your new home. There is no longer any reason to use wood products in areas of the US with high termite infestation. Consider steel framing, AZEK Trimboards and V-Buck for your next project and get the wood out! Although many additional myths exist and continue to thrive, it is important that you keep diligent in your information gathering. As you seek additional information, be sure to work with those that have the heart of a teacher. Seek those that have a passion for the industry and both understand and can explain the issues.