Residential

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.