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:

1. 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.

2. 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.

3. 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.

4. 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.