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.