Date:October 25, 2012
Posted by:Gary Brown
Tags:icficf constructioninsulated concrete formswood-frame
Are ICFs worth the added initial cost?
The Canadian winter is a worthy adversary and every year we utilize a wealth of natural resources in keeping it at bay. One of the most effective arrows in the green building quiver are ICFs. These insulated concrete forms enable home and business owners to protect their buildings against the winter cold and summer heat. Creating an effective building envelope helps to reduce greenhouse gas emissions and slash energy consumption. ICFs do cost more and so we must weigh the benefits of this cutting-edge building technology against the added cost to see if the initial outlay is worth it.
So just how much more do ICFs cost?
ICFs are polystyrene blocks that are stacked to form the building’s outer shell. The wall systems are reinforced with rebar and then filled with concrete to form an insulated barrier against energy loss. Thanks to the revolutionary construction method, the walls can be built in a fraction of the time it takes to create traditional homes. Despite the savings in labour and time, the ICF wall systems will still cost 10-15% more than a traditional 2×6 wood-frame structure.
Despite the large initial outlay, ICFs have a ROI of 10-12 years as the home and business owner enjoys reduced utility bills. It must be noted that this saving can only be expected in structures where the insulated building envelope’s integrity remains high. This means that ICFs must be complimented with high R-value window systems and adequate roofing insulation. Where the building envelope is sound, owners can anticipate a 30-40% reduction in energy bills when compared to a stick-frame building of equitable proportions. Of course these estimates do not take into account the increased resale value of a property built with ICFs.
Benefits of ICFs over wood-frame homes
Wood-frame homes have insulation gaps and thermal bridging through which precious energy is lost. The ICF structure is not afflicted by any of these issues and will enjoy an R-20 to R-28 rating for its entire lifetime. ICFs are extremely resilient and offer protection from fires, earthquakes, severe storms and flooding. ICF buildings can withstand winds of 200-300 mph (compared to the 120 mph of stick-frames) and have a 4-hour fire rating.
Because ICFs are made with concrete, they don’t rot or mold and are not affected by insects as is the case with wood-frame structures. Wood-frame buildings contain chemicals and adhesives that compromise indoor air quality throughout the building’s life. The concrete and EPS of ICFs are non-toxic and do not compromise indoor air quality at all.
The thick concrete walls created by ICF wall systems reduce noise by 30%, making them the perfect option for buildings near high traffic zones.
Impact on the environment
ICF homes last longer than wood-frame homes so the natural resources are used to maximum effect. Wood-frame homes utilize valuable timber and require more energy to heat and cool which results in more greenhouse gas emissions.
One of the biggest advantages offered by ICFs is thermal mass. Here the concrete walls absorb heat during the day and radiate this energy back into the house when temperatures drop. ICF buildings contribute a thermal mass of 20Btu/sq. ft. x °F compared to the 3 Btu/sq. ft. x °F offered by timber-frame homes.
Building with ICFs also vastly reduces construction waste when compared to timber-framed homes. 60% of the weight of ICF blocks is made up of recycled materials and ICF wall systems contribute 20 points to LEED ratings.
Accurate comparisons between homes are difficult at best. The integrity of a timber-frame home envelope depends largely on the quality of its construction. You can only take advantage of the added insulation offered by ICFs if the entire structure of the building is properly insulated (doors, windows, roofing and HVAC systems). Different ICF manufacturers offer different R-values and workmanship also plays a part in the overall energy savings.