LEED Construction Company Articles
the Myths of Insulating Concrete Form (ICF) 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 lack the appropriate knowledge behind
the information. The toughest part of researching ICFs is not finding the information,
but sorting through all of the inaccurate information.
Virtually every aspect
of the ICF industry is affected by misstated information, but the most common
issues involve 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
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 massive dense materials such as thick masonry or concrete. The larger the R-value,
the greater the resistance and the better the insulating value.
materials transfer heat to some degree. Heat transfer can be measured by any of
the following: 1. Conductivity (k); 2. Conductance (c); 3. Transmittance (U);
4. Resistance (R).
The ability of dense 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 2x4 stud wall is insulated with R-11 batt type 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 full of penetrations,
such as electrical outlets etc. and the fact that the wall itself is basically
hollow in nature. This added thought leads to another discussion on air leakage
through 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 solid 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 analysis. 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 ensure that the comparison is
being done vs. the alternative 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
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.
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.
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:
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.
Underseal™ 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 benefit, 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 through 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 remain 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.
is the founder of the Get Ready to Win Network. Contact Eric at email@example.com
or 928-255-5379. For more information about Eric, click here: ericwilliams.48dayscoach.com
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