INSULATED CONCRETE FORMS FREQUENTLY ASKED QUESTIONS
ThermoForm creates homes and buildings that are more energy efficient, stronger, more sound resistant, and more environmentally sustainable than any other construction method.
Yes. Every major code body in North America, including ICC and CCMC, has approved the use of ThermoForm as an accepted method of forming walls. Also, ICFs are listed as a prescriptive method of building in the International Residential Code and can be built to commercial design specification using the International Building Code.
Yes. ThermoForm buildings are up to 8.5 times stronger than wood framed buildings. As a result, ThermoForm walls are more able to withstand severe weather. Also, ThermoForm has passed its corner burn test issued by South West Research Laboratory.
A wooden or vinyl buck is built and incorporated into the wall as it is being stacked prior to pouring the concrete. Once the concrete is cured, doors and windows are installed as usual.
As with any form of below-grade construction, waterproofing is required. Recommended waterproofing of ThermoForm walls consists of a protective sealant to the EPS and XPS foam, coupled with a drainage mat surrounding the foundation wall. A drain at the footer is recommended and may be required by code. ThermoForm foundation walls should be allowed to cure for a minimum of 7 days and the first floor set in place or the top of wall braced prior to backfilling. The backfill material should be well drained and free of construction debris and large rocks. Once in place, backfill should be properly compacted and graded so that water does not collect around basement walls. Landscaping should be kept clear of the immediate perimeter to prevent accidental water damage from irrigation.
The points at which utilities connect to the building should be identified prior to the pour. This will allow for conduits to be placed through the wall so that the utility can enter. Once the concrete is poured and cured, for ThermoForm channels or grooves are cut directly into the form using and electric hot knife or router. Plumbing and electrical lines are then inserted into the grooves and covered by drywall
The best method to protect against termite infestation is to eradicate the colony and prevent them from setting up shop on your property. The National Pest Management Association recommends preventing termites by: “Removing the conducive conditions termites need to survive.” Termites love moisture; avoid moisture accumulation around the foundation of your home. Divert water away with properly functioning downspouts, gutters and splash blocks. Reduce humidity in crawl spaces with proper ventilation. Prevent shrubs, vines and other vegetation from growing over and covering vents. Be sure to remove old form boards, grade stakes, etc., that was used during building construction. Remove old tree stumps and roots around and beneath the building. Most importantly, eliminate any wood on the building from contact with the soil. An 18-inch gap between the soil and wood portions of the building is ideal. It doesn’t hurt to routinely inspect the foundation of your home for signs of termite damage.” Additionally, the Insulating Concrete Form Association recommends soil treatment and re-treatment over the life of the home. Just because the home is built of concrete does not mean the termite will give up trying to get to its food source: wood! When using ICFs below-grade, the International Residential Code calls for chemical treatment of the soil and an approved method for protecting the foam, such as physical barriers. TF Systems allows you the unique ability to use Perform Guard (a borate treatment) in its polystyrene as an additional defense against termites and other burrowing insects.
No. The combination of concrete and two layers of foam means that the ThermoForm walls acts as a natural barrier against air and moisture.
A ThermoForm wall has a sound transmission classification of approximately STC 50, which is twice as high as a typical wood-framed wall. Loud noises outside a ThermoForm building will be reduced to a whisper inside the building.
Over the last 20 years builders have been asked to build tighter wood homes using house wraps, seals, caulk, tapes and gaskets to reduce the amount of air infiltration/loss in the home. When these products fail, moisture gets trapped inside the open cavity of a wood stud wall, causing mold and mildew problems and rot. ThermoForm is a closed cavity construction, with the concrete filling the entire cavity of the wall. They are resistant to mold and mildew problems because they are composed of three inorganic materials that do not attract water: foam, steel reinforcing bar, and concrete.
LEED was launched in an effort by the United States Green Building Council to develop a “consensus-based, market-driven rating system to accelerate the development and implementation of green building practices.” The LEED NC V3 (New Contruction) rating system has four main credit categories: sustainable sites, energy and atmosphere, materials and resources, and indoor environmental quality. Each category is divided into credits, which correspond with possible points. The rating is based on the entire building system, and not on any individual product. The most important and direct contribution by ThermoForm walls are toward the Optimization Energy Performance credits, which offer up to 19 points. This is the only credit with so many points possible and represents a significant portion of the overall 49 point possible for a LEED Certified Project. The Energy Optimization Credit is based on the percentage of energy savings above the ASHRAE benchmark. The energy savings benefits of ICFs can play a significant role in the gaining of these points. ThermoForm and concrete can also contribute toward credits for recycled materials, sustainable sites, regional materials, and durable structures. To learn more about this program, please visit the US Green Building Council’s website at http://www.usgbc.org/
Based on research performed by Building Works, Inc, houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable wood-frame houses. A typical 2000 square foot home in the center of the U.S. will save approximately $200 in heating costs each year and $65 in air conditioning each year. The bigger the house the bigger the savings. In colder areas of the U.S. and Canada, heating savings will be more and cooling savings less. In hotter areas, heating savings will be less and cooling savings more. The energy efficient performance comes in large part from the polystyrene foam on the interior and exterior of ICF walls, which range from R-17 to R-26, compared to wood frame’s R-9 to R-15 walls. Also, ThermoForm walls are tighter, reducing infiltration (air leakage) by 50% over wood-frame homes.
Yes, our certified contractors would be more than willing to assist in the beginning stages of building in order to train individuals.
This will be determined by the design parameters of the building, and in accordance with local building codes. Additionally, Portland Cement Association and ICFA sells Prescriptive Method for Insulating Concrete Forms in Residential Construction (2nd Edition) through its bookstore, which provides tables that provide a guideline for most common applications.
ICFs have been engineered and built to 48 feet tall (free standing/load bearing). It is important to note that in most applications, ThermoForm projects can be designed using ACI 318 and are designed like any other steel reinforced concrete wall. Residential projects of up to two stories may also be designed in accordance with the IRC Section R611 or the Prescriptive Method for Insulating Concrete Forms in Residential Construction (EB118)
It’s best to try and avoid this condition – particularly mid-height of a wall (i.e. halfway between lateral supports such as a floor slab, an interconnecting floor or a roof) This is because that point on a wall height is where the maximum bending movement or deflection will occur in the wall when the backfill comes against it (in a below grade application) OR when the wind acts against it (in an above grade application). It’s at this point that the wall requires its greatest strength to resist bending. In fact, the wall acts just like a floor slab does in a suspended floor assembly when load is placed on it. However, in many cases with taller wall heights (above 10 feet), it’s simply impossible to practically construct without having a cold pour joint, particularly when the contractor is also concerned about maximum drop height of concrete in the wall or access for internal vibration. Fortunately, the ACI 318 Concrete Standard (the concrete code) in the US and CAN/CSA A23.3 in Canada both permit walls to be constructed in stages with cold pour joints provided that: A. The vertical reinforcing bars that are installed in the base portion of the wall are cut such that they will extend upward beyond the designated cold pour joint line by at least 40 times the diameter of the reinforcing bar being used. Most reinforcing bars will either be #4 (4/8 or ½” diameter) or #5 (5/8 or 5/8” diameter) bar Therefore, 40 x ½” = 20” or 40 x 5/8” = 25”. More lap length is obviously better. As long as it exceeds these minimums, the installation will comply with Code. This lap area in the wall is known as the lap splice length. B. As an alternate to above, reinforcing stubs cut to twice the designated lap splice length could inserted into the top of the first pour immediately beside the bars of the base pour such that ½ of the bar is buried in the first pour and ½ extends above the top of the concrete pour. If your bar spacing exceeds 2’0” on center, you will need to cut a sufficient number of bars to assure that the maximum space between these bars is no greater than 2’-0”. C. In addition, the vertical reinforcing bars between subsequent pours must never be spaced more that 1/5th the lap splice length apart from each other nor any greater than 6” apart (so if the lap splice length is 25” the bars should be no farther apart than 5”). To attain this, you’ll see some ICF installers use a 2-inch deep ring of 3” diameter ABS pipe cut-off dropped around each bar to assist the installer in holding the bar in place. D. Next, the top of the first pour of concrete should be left rough in texture between the pours so that the wet concrete of the subsequent pour is able to secure a better grab to the previously cured lower layer of concrete below. E. Finally, the second pour of concrete should be adequately vibrated to consolidate the wet layer at the cold pour joint as much as is physically possible to assure there is as little honeycombing as possible at this very crucial joint. All of these steps will help to ensure that a cold pour joint in your wall will conform to the ACI 318 or CNA/CSA A23.3 requirements for wall pours.
Standard depth electrical boxes can be cut and fitted directly into the interior foam panel beside a metal or plastic rail by cutting the foam to a 2 ¼” depth (leaving 3/8” foam covering the concrete). Boxes can either be metal or plastic (Nurell® Nylon or other ULC or CUL approved box products). Normally cuts are made using pre-profiled hot knife attachments.
ThermoForm walls have metal or plastic rails that run vertically from the top of the form to the bottom, allowing a fastening strip for mechanical attachments, such as exterior siding, brick ties and drywall. The flange is engineered to withstand high pull out stresses and is designed to keep the materials securely attached for decades. In all cases, most exterior and interior cladding can be installed with common attaching screws.
Most acrylic finishing systems are comprised of a reinforced base coat, optional primer and a 100% acrylic polymer finish. Finishes are available in a limitless color selection and offer performance enhancement options. Exterior acrylic systems are perfectly suited to ThermoForm walls that have exposed exterior foam, as the preparation for applying an acrylic system to the walls requires only rasping the foam before application. Portland cement stucco is also a very durable and can create an endless variety of colors and textures for an exterior of a ThermoForm house or building. When stucco is applied to metal lath, three coats of plaster form a 7/8-inch total thickness. A vapor-permeable, water-resistant building paper separates the plaster and lath from the ThermoForm. It’s a proven system that works in all climates.
Having the right concrete mix design is important to ensure that a project goes smoothly and without incident. In ThermoForm projects, it is recommended that a 3000 psi with a 3/8” smooth aggregate and slump of 5 ½ – 6 be used. However, there have been great advancements in mix design over the past several years that allows one to alter the design mix to provide for better flow and viscosity without increasing hydrostatic (or what is commonly referred to as form) pressure. A common mistake individuals make is adding more water to the concrete on the jobsite to the mix to increase the flow and viscosity. Do not do this. If the slump is above 6, it will cause the form pressure to dramatically increase, causing a tear in the foam form. Instead, consider asking for a percentage of fly ash to be added to the mixture prior to delivery to the mix to increase the flow. Not only is it increasing the flow of the mix, it is also reduces the amount of cement in the system allowing for the increased use of recycled product in the project.
Concrete placement ThermoForm walls is best accomplished with a concrete pump, or alternatively from the truck chute or conveyor belt for below grade applications. Concrete placement in ThermoForm walls is governed by the ACI-318, Building Code Requirements for Structural Concrete. There is no limitation on concrete pour heights or lifts in this document, nor is there any requirement for the pump to be lowered into the formwork. Field studies have shown that free fall from great distances doesn’t result in concrete segregation nor in reduction in compressive strength. In ThermoForm construction, concrete placement will typically begin by placing concrete through opening in the window sill plate. Subsequent placement will take place from the top of the form, in lifts of approximately 4 ft, for a continuous pour to the final wall height. It is recommended to avoid placing concrete too close to corners, openings or thin columns, in order to not unduly stress the forms. A hose reducer with a flex hose is helpful for more precision placement. During the pour, the ThermoForm walls should be monitored for plumb, and the bracing adjusted accordingly.
Yes! Becoming an ICF Construction Specialist takes a little bit of skill and a lot of heart. TF Forming Systems offers professional training for those interested in becoming construction specialists, and it only takes a small investment. The tools needed for ICF construction are basic tools because of our efficient application of the system. There is always a need for ICF Construction Specialists, so if you are interested in learning, contact us today!