General

Problems with ICF Construction

Com­mer­cial con­struc­tion using insu­lat­ed con­crete forms (ICF) is an option avail­able to build­ing design­ers in cer­tain sit­u­a­tions. But there are impor­tant con­sid­er­a­tions to weigh when com­par­ing ICF con­struc­tion to com­pet­ing con­cepts.

What are Insulated Concrete Forms?

ICF walls are cre­at­ed by pour­ing rein­forced con­crete into hol­low pan­els, typ­i­cal­ly made of either extrud­ed poly­styrene foam or expand­ed poly­styrene. Before the con­crete is poured, the inter­lock­ing units are dry-stacked, which is a bit like build­ing with Lego bricks.

Once the con­crete is poured and cured, the ICF pan­els form a per­ma­nent exte­ri­or frame­work that can be used in struc­ture up to five sto­ries high. The inner and out­er poly­styrene pan­els remain per­ma­nent­ly in place, usu­al­ly sep­a­rat­ed by 6 – 8 inch­es of con­crete rein­forced with rebar. These pan­els allow the instal­la­tion of plumb­ing and elec­tri­cal con­duits lat­er on in the process. Dry­wall can be affixed to the inside pan­els, and exte­ri­or cladding can be attached to the out­side pan­els.

ICF con­struc­tion ini­tial­ly gained momen­tum in part because it pro­vid­ed greater wind resis­tance and ener­gy effi­cien­cy than wood-frame res­i­den­tial con­struc­tion. Insu­lat­ed con­crete forms have also been used in com­mer­cial struc­tures that are only a few sto­ries high.

The Disadvantages of ICF

Although there are advan­tages to ICF con­struc­tion, it has its share of prob­lems:

Con­struc­tion Issues — Dur­ing con­struc­tion, the process of fill­ing an ICF wall with con­crete some­times caus­es prob­lems. Expe­ri­enced con­trac­tors know how many feet of con­crete can be poured at a time with­out risk­ing so-called blowouts.” When con­crete is poured at too rapid a rate, it can burst through the poly­styrene pan­els, which can result in a cost­ly cleanup and con­struc­tion delays.

As it is poured, the wet con­crete must also be suf­fi­cient­ly vibrat­ed to elim­i­nate all air pock­ets and voids (a ten­den­cy often referred to as hon­ey­comb­ing”). Hol­low areas can reduce the strength of an ICF wall, decreas­ing its wind resis­tance. In extreme cas­es, an ICF wall con­tain­ing voids may even be unsta­ble.

Ground­wa­ter and Insects — Design­ers and archi­tects must account for the fact that reg­u­lar ICF pan­els are vul­ner­a­ble to ground­wa­ter intru­sion. Drainage tiles and drainage sheet­ing are often required to min­i­mize the adverse effects of the result­ing mois­ture. These com­po­nents add to over­all costs.

Although ter­mites are usu­al­ly asso­ci­at­ed with wood con­sump­tion, they have, on occa­sion, also bur­rowed through ICF poly­styrene pan­els and tiny cracks in the con­crete. Once they get through an ICF wall, they may go on to feast on joists, floor­ing and oth­er wood com­po­nents. Although the ter­mite prob­lem can be addressed proac­tive­ly through a vari­ety of means, these all rep­re­sent addi­tion­al steps to the exte­ri­or wall con­struc­tion process.

R-val­ues and Ener­gy Effi­cien­cy — It used to be easy to demon­strate that the insu­lat­ing val­ue of ICF pan­els is high­er than that of tra­di­tion­al wood stud walls con­tain­ing fiber­glass insu­la­tion. But since codes now require con­tin­u­ous insu­la­tion, ICF has now lost that advan­tage.

With the arrival of the 2015 Inter­na­tion­al Ener­gy Con­ser­va­tion Code (IEEC) updates, the ener­gy effi­cien­cy of exte­ri­or wall sys­tems has become more impor­tant than ever. While com­pa­nies want to accu­mu­late LEED points for ener­gy effi­cien­cy, they also want an ide­al bal­ance between R-val­ues and wall sys­tem costs.

Poly­styrene Pan­els and Recy­cled Con­tent – The con­crete poured into the ICF pan­els may con­tain fly ash or oth­er recy­cled mate­r­i­al, and the rebar may include recy­cled steel, but post-con­sumer waste can­not be used in the poly­styrene pan­els because of the poten­tial for con­t­a­m­i­na­tion.

Bau­tex Block wall sys­tems are a cost-effec­tive, ener­gy-effi­cient alter­na­tive to ICF walls. To learn more about using Bau­tex Block for your next project, please con­tact us.