March 23, 2018

How to Build an ICF Home

Why build an insulated concrete form (ICF) or insulated concrete block (ICB) home?

An ICF or ICB home, like the Bautex Block System, is a wise choice for today’s energy and safety-aware homeowners. An ICF home is energy-efficient, fire-resistant, and can withstand flying debris from tornadoes and hurricanes with wind speeds of up to 250 mph. ICF and ICB construction is also quiet, low maintenance, healthy, and has a lifespan that is significantly longer than traditional building methods. Specifically, ICF and ICB homeowners can expect the following benefits over a wood-frame home: 20 percent or more energy savings, 10-30 percent less outside air infiltration, twice the strength, three times quieter and a 4-hour fire rating. Building an ICF or ICB home saves money, energy, and improves the safety and comfort for its occupants.

What to Consider When Building an ICF Home

Building an ICF home can be an enjoyable and exciting experience for new homeowners. An ICF home provides many of the essential features today’s homeowner is looking for, like energy-efficiency and disaster-resistance. However, there are several things homeowners should consider before building an ICF home: risk and ease of construction, pest-resistance, moisture intrusion, wall thickness, and cost. Read on for considerations when building an ICF home and why the benefits of ICB, like Bautex, make it a better choice for your insulated concrete wall home solution.

Consider the Risks and Ease of Building an ICF Wall

How to Build an ICF Wall System: Insulated concrete forms (ICFs) are cast-in-place concrete walls, sandwiched between two layers of insulation. Insulated concrete form walls are made by dry-stacking interlocking hollow extruded polystyrene foam or expanded polystyrene foam panels to a wall’s length. The forms are reinforced and braced. Trained professionals then pour concrete into the hollow form panels. It is during the pouring of the concrete that problems occasionally occur that can impact the integrity of the wall.

1.  If the concrete is poured at too rapid a rate, it can burst through the polystyrene panels (a blowout). A blowout results in costly cleanup and construction delays. Bulging of the ICF panels can also result from going too fast, which can affect the straightness of the finished walls.

2. ICF panels are extremely lightweight and must be sufficiently braced and supported during the concrete pour to ensure that the walls remain plumb. Contractors must also make quick adjustments to the bracing to compensate for any movement of the walls during the concrete pour.

3. Sufficient vibration during the pouring of the concrete is essential for eliminating the formation of air pockets and voids. Air pockets and voids can reduce the strength of a home, along with the home's resistance to air, moisture, and insect intrusion.

Building an ICF wall requires experienced professionals that understand the complexities and challenges of ICF construction and have all the necessary equipment to provide a quality installation. When properly built, an ICF wall creates a tight building envelope with strong structural integrity. However, any construction defects can significantly impact the overall performance of the ICF building if not installed accurately.

How to Build an ICB Wall System: Insulated concrete blocks, like the Bautex Block System use similar technology as ICF but eliminate much of the complexity. The Bautex Block is a lightweight composite block with the strength and fire resistance of cement and the insulation properties of expanded polystyrene foam. The Bautex wall system is installed by first laying the blocks end-to-end to form the exterior walls of the home. After placement of the EPS-cement blocks, they are glued together for temporary alignment. During this step, it is easy to add design details and wall penetrations. Next, steel rebar is installed in all of the horizontal and vertical cores within the wall. Following an inspection, trained professionals pour high-flow structural concrete into the hollow cores formed by the blocks. The strength and composition of the composite blocks, the air permeability of the blocks, and the fact that only half the amount of concrete is used compared to ICF, all help to avoid issues of bulging, blow-outs, and air pockets sometimes experienced with ICF construction. The result is a single, integrated wall system, which provides structure, insulation, and air and moisture protection. The Bautex Block System uses one trade, fewer materials, fewer steps, less labor, and is simpler to install than foam plastic ICF systems.

Consider the Pest Resistance of ICF

ICF homes are not termite proof. Termites can enter an ICF home by tunneling through the EPS insulation. Once inside the home, the termites can feast on untreated wood in the walls, floors, and roof. Below-grade ICF is a particularly easy conduit for pests to enter a home. Importantly, the 2015 IRC, section R318 mandates that foam plastics not be installed below grade in areas where termite damage is heavy, like Texas. Termite protection is essential for ICF homes.

How to Termite Proof an ICF Home

1. Protect an ICF home from termites by using non-organic materials such as steel studs or pressure treated lumber on all interior partition walls and roof truss. This method denies the termites a food source.

2. In regions subject to termites, as indicated by Table R301.1 of the IRC, apply one or more approved methods1 for protecting foam plastic from termites: termite shields, inspection strips, insecticides, sand barriers, and membrane materials.

  • Termite shields create a barrier so the termites cannot tunnel through the foam. Typically termite shields, made from durable plastic or metal, are placed like a cap across the width of the ICF sidewall. The termite shield's goal is to force the termites out of the foam. Once out, the termites will build a mud-wall over the barrier to avoid light. The mud-walls alert the homeowner of the presence of termites so a treatment program can begin.
  • Create an inspection strip by removing the exterior foam in a six-inch strip around the entire building just above grade. The inspection strip forces the termites into the light, which exposes mud tubes and the presence of termites.
  • Treat the foam with an insecticide, like imidacloprid, which is highly termite-resistant.  Imidacloprid is fully certified by the International Code Council Evaluation Services (ICC-ES) as an approved treatment against insect attacks on EPS (ICC-ESR 2918) and meets the requirements of ICC-ES AC239, Acceptance Criteria for Termite-Resistant Foam Plastics.
  • Sand barriers are another effective measure of termite exclusion. Four important sand barrier properties must be considered to ensure effective subterranean termite exclusion: particle size, particle hardness, particle angularity, and interstitial space.
  • Install membrane materials that are effective in protecting the below-grade foam from both insects and moisture.

Termite-Resistant Bautex Blocks

Bautex composite concrete blocks are pest resistant. Utilizing Bautex Wall Systems eliminates the need for further pest-proofing measures required by ICF homes.

  • Bautex Blocks are free of organic material. Termites feed on organic material.
  • The Bautex Block encapsulates its insulation in cement, which further reduces the chance that termites will burrow into the material.

Consider the Waterproofing Issues with ICF

With an airtight, energy-efficient ICF home, even a small amount of water entering through the walls can cause major problems. Moisture can cause rot for some materials, which impacts the home’s durability. Moisture can also cause the growth of mold and mildew, which can degrade indoor environmental quality. While many in the industry argue that ICF walls do not need supplementary moisture protection, experience has shown that ICF homes are also susceptible to moisture intrusion problems.

  • The interlocking edges of the ICF forms are not watertight and can allow water to migrate behind the foam plastic.
  • Concrete shrinks as it cures, which creates tiny gaps between the concrete wall and the ICF panels.  These gaps are a perfect path for moisture to travel down the wall.
  • Building an ICF wall starts with stacking insulation panels that form the concrete wall. A tie is then used to hold the panels together and create a cavity for placing the concrete. The concrete is typically poured in multiple lifts using vibration to minimize air pockets. Improper pouring of lifts may create gaps that allow for water intrusion. If the first lift of concrete sets before the pouring of the next lift, the two batches do not mix well, and a cold joint can form, which may let water seep into the wall system.
  • Any voids in the concrete wall due to incomplete consolidation are also potential entry points for water.

Once water enters an ICF wall, it can create issues on the inside of the building including interior finishes, flooring, and adjacent intersecting walls, which can all be vulnerable to moisture. It is essential to include a quality waterproof system in the design of an ICF home.

While less likely to trap moisture like ICF, the Bautex Wall System also requires a quality above-grade moisture barrier system. A quality bulk water control system must include quality materials, good job site preparation, and careful application.

Application of a Quality Moisture Barrier System to ICF and ICB

The first defense for a quality water resistant wall assembly is applying a moisture barrier membrane to the wall. Common moisture barrier products include peel-and-stick membranes and fluid-applied membranes.

Peel-and-Stick Waterproofing Membranes

Peel-and-stick membranes are self-adhered membranes that consist of three layers.

A  backing that is peeled away just before application

The membrane

An outer surface film

Peel-and-stick membranes can be more costly than other options, but provide very consistent performance. Many peel-and-stick membranes require a primer to contain dirt and dust and increase adhesion. Most are water-based, but a few low-temperature primers are solvent-based. Importantly, solvent-based primers cannot be used on ICFs because the solvent will dissolve the foam. As with any moisture barrier system, ensuring complete adhesion to the wall substrate, proper lapping of sheets, and managing the details at openings and transitions is vital and can present some challenges to contractors.

Fluid-Applied Moisture Barrier System

A fluid-applied air and moisture barrier system is an excellent option for waterproofing an ICF or ICB home.  Fluid-applied systems are applied as a liquid and cure into one monolithic seamless membrane that is fully adhered to the wall substrate. An advantage of the fluid-applied system is it gets into all the nooks and crannies. A fluid-applied system also has the flexibility to be touched up as the construction project progresses.  A fluid-applied membrane is an excellent moisture barrier option for ICF and ICB homes.

The Bautex AMB 20 Air and Moisture Barrier

The Bautex AMB 20 air and moisture barrier is a fluid-applied membrane that creates a monolithic protective barrier that prevents air and moisture infiltration to the interior of a home. The Bautex AMB 20 air and moisture barrier also meets and exceeds the requirements of most residential construction projects. Application of the Bautex AMB 20 air and moisture barrier to Bautex Block, concrete, concrete block (CMU), ICF, or exterior sheathing materials is quick and efficient and creates a quality moisture barrier system.

Design Considerations for ICF Home Plan

Insulated concrete form construction is compatible with essentially all home designs. Once built, an ICF home looks just like a traditional-framed home. A primary consideration when designing an ICF versus wood-frame home is the extra thickness of an ICF wall (12+ inches). The extra-wide walls reduce room sizes and lessen the square footage of the home, which essentially increases the cost per square footage of building an ICF home. If a homeowner wants to maintain the original square footage, they must increase the overall dimensions of the home, which will also impact the design of the roof and foundation. Also, windows and doors must have wider jamb extensions to accommodate the increased wall thickness. Homeowners should expect to pay about $1000 to modify traditional home plans to ICF home construction. Once a homeowner considers the width of the ICF walls, there are no limitations on the type of designs for an ICF home.  

A further advantage of the Bautex Wall System over ICF is the Bautex Block is only 10 inches thick, which saves precious indoor space.

The Cost Considerations with ICF Construction

According to the U.S. Department of Housing and Urban Development (HUD), the initial cost for ICF construction can be between five and ten percent, or two to four dollars per square foot more than wood-frame construction. However, it is important to weigh construction cost for ICF against the longer-term benefits.  ICF houses are more energy efficient than wood-frame houses, so ICF homes require smaller heating and cooling equipment. Less expensive heating and cooling equipment can cut the cost of the final house by an estimated 75 cents per square foot, according to the EPS Industry Alliance. Also, ICF walls reduce heating and cooling energy use by an estimated 30-40 percent, amounting to a savings of 200-300 dollars per year for a typical home.  A home built with high-quality ICF or ICB is the smart, economical choice because the long-term financial benefits outweigh the initial construction cost.

Building a home with insulated concrete forms (ICF) has many advantages, but there are a few complications new home builders should consider before choosing an ICF wall system. ICF creates a house that protects homeowners from tornadoes, earthquakes, and hurricanes. An ICF home also creates a building envelope that is energy efficient, quiet, and low maintenance. However, there are several issues new home builders should consider before choosing an ICF wall system. ICF homes are susceptible to problems during construction that can lead to pest and moisture intrusions. In addition, the thickness of ICF can impact the square footage of a home and may add cost to the project. A solution to these challenges is the Bautex Insulated Concrete Block System. The Bautex Block System is a monolithic wall that is energy-efficient, pest-proof, fire-resistant, and can withstand flying debris from tornadoes and hurricanes with wind speeds of up to 250 mph. Bautex Blocks are also easy to install and less thick than ICF. The Bautex Block System saves homebuilders time and money and reduces construction risk.

The Auto Haus - An Insulated Concrete Block Home in Texas

The Auto Haus, in Austin, Texas, exemplifies how the Bautex Wall System can create a secure, safe,  moisture-resistant, energy-efficient home with temperature and humidity controls. These features were essential to the Auto Haus homeowner who wanted to build a home that efficiently integrated a 15-car garage to store their prized car collection adjacent to their residential space. The homeowner wanted a home with a simple wall design, that was durable, fire-resistant, energy-efficient, moisture-resistant,  and low maintenance. The home also needed a high level of security. The Bautex Wall composite system simplified the overall design and construction of the home in one integrated wall assembly, which saved the homeowner time and money. The Auto Haus is a moisture and fire-resistant, energy-efficient home with temperature and humidity controls. The design of the home also protects the occupants, their belongings, and their valuable cars.

Visit Bautex Wall System for more information how to build an insulated concrete block home.

1 The definition of “approved protection” varies widely between jurisdictions and inspectors.


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