Frequently Asked Questions
Does it cost more to build a CELBLOX ICF project than to build with wood-framing, CMU, or poured wall?
The cost of building with CELBLOX® is comparable to building with 2 x 6 wood framing and insulation. However, CELBLOX can reduce initial HVAC installation costs since smaller size equipment is needed for both heating and cooling. Heating and cooling costs for the completed structure can also be reduced by up to 50% or more due to the superior insulative properties of ICF walls. Upkeep costs like maintenance and insurance are also less.
While the initial cost of ICF walls can be more than standard poured concrete or CMU walls, CELBLOX ICFs stay-in-place forms provide the insulation, furring strips (the polymer web), and vapor barrier that poured and CMU walls cannot provide without the extra costs of adding insulation and furring.
THE RULE OF 72
The Rule of 72 is the time it takes to double your investment. Applying this principle shows the value of building with CELBLOX.
Although building with CELBLOX may cost more when compared to wood-framing, you gain the benefits of sound attenuation, disaster resistance, and lower maintenance costs. The energy savings that CELBLOX walls provide is payback on the extra investment needed to purchase these benefits.
For example, suppose you invest $2,000 to upgrade your building envelope from wood-framing to CELBLOX ICFs. This upgrade then saves you $400 per year on energy costs. In five years the income from the energy savings has paid for the added cost of building with CELBLOX. You now own the CELBLOX walls and your original cash investment. You have therefore doubled your investment! Your return on investment would be 14.4%!
Are there any insurance benefits to building with CELBLOX?
CELBLOX ICF can qualify for lower insurance rates since the walls are considered by insurance companies to be a “superior” type of construction as they have a 2-4 hour fire rating and can be used in Types I, II, III, IV, and V construction. Studies have shown that CELBLOX ICF wall assemblies can withstand winds of up to 300 mph.
Does it take more time to build with CELBLOX?
An experienced ICF contractor can install CELBLOX ICF walls in the same time, or less, than building a traditional wood-framed building. ICFs are faster than CMU construction since CMUs are labor intensive, have daily stacking height limitations, and require heavy equipment to move product to job staging areas.
If your installer has never worked with ICFs, CELBLOX has the expertise to provide training and technical assistance for your project. We are committed to fully supporting your project through the CELBLOX ICF installation process.
Are CELBLOX ICF walls stronger than traditional poured walls?
Yes. CELBLOX ICF walls produce a moist cure allowing the concrete to cure chemically to its maximum strength. An ICF walls reaches 4800 psi strength at 28 days and continues to cure beyond that to up to 50% stronger traditional poured walls. When cured, CELBLOX walls can reach strengths of up to 8000 psi – more strength than traditional poured walls.
How does a CELBLOX ICF wall compare to that of a concrete block wall in terms of structural capacity?
An 8’ below-grade wall backfilled to 7’ with sand and gravel would require a 12” CMU block without reinforcement or an 8” CMU block reinforced with vertical #6 rebar on 4’ centers. A CELBLOX ICF 6” concrete core wall with #4 rebar on 16” centers can be built faster and with less labor making CELBLOX the better choice.
What is the R-value of CELBLOX ICF walls compared to other construction methods?
The actual R-value of a CELBLOX ICF Wall, with concrete in place, is 22 for all concrete core widths. The R-value of a typical 8” thick concrete wall is 1.35 according to the American Society of HVAC Engineers’ Handbook. Doubling the wall thickness only increases the R-value to 1.85. According to the Masonry Advisory Council, a typical 6” CMU without additional insulation has an R-value of .45.
However, the performance R-value of a CELBLOX ICF wall, based on energy savings and studies of thermal resistance, can commonly reach R-50.
Is CELBLOX a “green” building product?
CELBLOX is green in many ways. CELBLOX ICFs have hinged connectors allowing more product to be shipped in less space, saving on fuel and shipping costs. The EPS can be 100% recycled and emits no CFCs, HCFCs, or VOCs. Building with CELBLOX saves about 21 trees per typical residential project and considerably more on commercial projects. Heating and cooling costs can be lowered up to 50% or more for a CELBLOX ICF building and minimize impact on natural resources. These are just a few of the reasons why CELBLOX ICF is an environmentally “green” building material.
Does the CELBLOX ICF emit any VOCs or other gasses?
In CELBLOX ICFs, the panels are composed of Expanded Polystyrene (EPS). EPS does not contain any VOC, formaldehydes, or other toxic gasses. It is not considered toxic by the
Are CELBLOX ICF buildings more comfortable than those built with other construction methods?
Although reduced energy costs and disaster resistance are typically reasons given for choosing CELBLOX ICFs, people working and living in ICF buildings most often say comfort is their favorite feature. There is no air leakage through the walls which eliminates drafts and hot or cold spots. Outside noises are reduced and/or eliminated by ICF walls that have an STC rating of 51 or higher – much better than any other construction method.
Are CELBLOX ICFs susceptible to mold and mildew growth?
EPS, concrete, and rebar are all inorganic materials that do NOT provide moisture or a food source for mold or mildew. If an EPS panel is completely saturated in water, it can only absorb .3% moisture by weight – and most ICF panels are extremely lightweight. However, since the CELBLOX ICF building envelope is tighter than other methods of construction, it is important to work with your HVAC contractor to ensure correct airflow in the building.
Is the EPS used in CELBLOX ICFs flammable?
The outer walls of CELBLOX ICFs are made from flame-retardant EPS foam which is fire resistant, non-toxic, and has a flame spread of zero. The inside of the walls are solid concrete which is not only non-flammable but can even act as a barrier providing protection against fires.
What types of design and plans can be used for CELBLOX ICFs?
Any design or any plan can be adapted to CELBLOX ICF construction including curved walls, open floor plans, tall walls, gable ends, and limitless other possibilities. While your plan does not have to be designed specifically for CELBLOX ICFs, you do need to consider the added width of the exterior walls. Although the exterior of an unfinished CELBLOX ICF wall may look dramatically different from traditional wood-framed construction, exterior finish methods are very similar. In fact, most exterior finishes can usually be applied to ICF walls more quickly and cost-effectively than can be applied to a wood-frame building.
Is there a maximum height for CELBLOX ICFs?
With proper engineering, CELBLOX structures can be designed for any number of stories above or below grade. There is no limit to the height of a project because CELBLOX walls, when engineered correctly, are structural, load-bearing walls and can be incorporated into any commercial or residential project.
Does CELBLOX have engineers who can review my drawings?
Although CELBLOX is committed to making the permit and design process as easy as possible; we do not have engineers on staff. However, PCA prescriptive data for residential construction is available in our installation manual for common building situations. Available prescriptive data includes typical details and wall sections, backfill tables, typical reinforcement requirements, and lintel information.
The CELBLOX installation manual is available at the following website link.
How are utilities installed in CELBLOX ICF walls?
EXTERIOR penetrations such as openings for incoming water, electric, and sewer lines, dryer vents, and penetrations for exterior electrical outlets and lights are cut through the EPS prior to pouring concrete.
All other plumbing and electrical is installed after the concrete has been poured. Channels can be cut anywhere needed directly in the 2 1/2” thick EPS panel which is deep enough to meet code requirements.
How do you attach siding, drywall or other finishes to CELBLOX ICF?
All exterior finishes and interior drywall are attached to the CELBLOX ICFs 1½” wide web located every 8” on center and indicated by a deeper and wider groove. These webs provide a continuous “furring” strip up to ¼” from top and bottom of the form, allowing for easier horizontal utility installation, and have a higher pull out strength than a dimensional stud.
Always follow manufacturer’s guidelines for specific product installation.
Is a vapor barrier required with CELBLOX?
According the standard ASTM E 96, to qualify as a vapor barrier, a material must not exceed 45 ng/Paּsּm².This unit denotes the ‘permeance’ of the material, meaning how much moisture per force applied (air pressure), in a second over a square area. CELBLOX EPS foam has a permeance value of 36 ng/Paּsּm² and, therefore, qualifies as a vapor barrier.
Do below grade walls in habitable space need to be covered?
To meet a thermal barrier requirement,
Is waterproofing required on CELBLOX ICF walls?
All below-grade walls in habitable space require waterproofing. Any waterproofing product used must be EPS compatible because solvent-based products will damage the EPS. Costs vary from product to product and type chosen will depend on project cost constraints. For whatever type of waterproofing used, ensure that the product meets local building codes and follow manufacturer’s installation recommendations.
What are the best increments to use for stepped footings?
When using CELBLOX ICFs for a stepped footing, 16” increments work best. However, if your stepped footing is not formed in 16” increments, you can cut the CELBLOX ICF forms from the bottom to match your footing.
Can concrete be poured into CELBLOX ICFs in cold weather?
Yes. If the average temperature in a three day period is below 40̊ F or 4.5̊ C then this would be considered to be a cold weather pour. Heated water can be added to the concrete and the mixture can also be changed so the full compressive strength of the concrete can be achieved in lower temperatures. If you have further questions please contact CELBLOX Technical Service Department or your local distributor.
Is there a maximum height that concrete can be poured from?
There is no clearly defined height at which the concrete and aggregate separate. In CELBLOX ICF walls the tie and rebar configuration does not cause segregation of the concrete and aggregate when poured from any height.
How tall can a CELBLOX ICF wall be poured in one day?
Concrete is typically poured to heights of 10’ to 12’. A lift height is how high concrete is poured in one pass around the perimeter of the wall. CELBLOX ICF walls are typically poured in lift heights of 4’ per hour according to ACI 318 standard practice. Therefore, a typical pour would consist of 2-3 lifts.
How is concrete properly consolidated?
The best way to consolidate a CELBLOX ICF wall is to internally vibrate the wall with a 1” or smaller vibrator. The vibrator should be lowered to the height of the lift and then vibrated one second per foot while pulling it out. Vibration is done the total height of one lift every 16” across the wall.
Do CELBLOX ICFs deteriorate when exposed to UV?
UV rays can deteriorate the surface of the EPS if not covered in a reasonable construction cycle. Therefore, it is best to leave them wrapped until being placed in the wall. After the wall has been up for a length of time without being covered, it will chalk. Chalking is a surface condition and does not affect the integrity of the CELBLOX ICFs. It can be easily brushed or washed off before applying stucco-type coatings.