Let’s Talk About Insulated Concrete Forms (ICF)
Connecticut Passive House welcomed featured guest Ken Lynch from Tremco Construction Products Group (a BuildGreenCT Supporter Sponsor) to our March roundtable. He shared an overview of Tremco’s extensive product line designed to protect building envelopes from moisture, air infiltration, and thermal inefficiencies.
His primary focus was on Insulated Concrete Forms (ICFs), a construction method offering energy efficiency, fire resistance, soundproofing, and structural durability. An ICF system offers energy efficient benefits through its continuous insulation, thermal bridge-free construction, airtight construction, and thermal mass. These factors lead to lower heating and cooling demands, reduced air infiltration, stable temperatures, enhanced comfort, and decreased energy consumption.
Did you notice how many Passive House boxes are checked?
Nudura ICFs are composed of two expanded polystyrene (EPS) panels held together by engineered ties, which also support reinforcement bars. Once filled with concrete, these forms create an insulated, reinforced monolithic concrete wall. This product line offers large panel sizes for faster installation and reversible corner pieces that simplify construction.
Ken shared some perks of ICF construction:
- Seven Elements in One Product: A single product installed by one subcontractor can cover structurally reinforced concrete, a continuous air barrier, continuous insulation, a vapor barrier, a fire-resistant assembly, integrated interior and exterior attachment strips, and a high sound transmission classification (STC). This streamlined construction reduces scheduling conflicts and avoids incompatibility between materials.
- Installation & Labor Advantages: ICFs fall under the carpenter trade for union projects, but any trade, including concrete contractors, can be trained to install ICF, making installation easier to staff compared to traditional concrete forms. The lightweight forms simplify construction, reducing labor needs, increasing speed, and improving job site efficiency.
- ICFs in Passive & Net-Zero Buildings: A net-zero school in Kentucky – the first in the country – uses ICFs to reduce energy costs, improve durability and indoor air quality. A Passive House affordable housing project in Queens, NY uses ICF technology to meet stringent energy efficiency standards and help reduce sound from a busy city environment.
- Reducing Embodied Carbon: ICFs help lower embodied carbon by reducing concrete use in foundations by up to 40%. Using alternative materials like slag, fly ash, or recycled glass pozzolan further reduces the carbon footprint.
- Resilience Against Natural Disasters: Fire and wind events are becoming more prevalent. ICFs offer up to a four-hour fire rating and can withstand winds up to 250 mph.
Remember that “last house standing” picture after Hurricane Michael in Florida? That was ICF. - Soundproofing Benefits: With an STC rating of 50-70+ (compared to 30 for wood-frame construction), ICFs reduce noise transmission — a concern for apartments, hotels, offices, and medical facilities.
Did you know sound is a top reason people move? Consider that from a developer’s standpoint. - ICFs & Building Codes: Classified as “mass walls,” ICFs leverage concrete’s thermal mass to regulate indoor temperatures. In Connecticut, ICFs need an R-13 rating compared to R-30 for conventional construction. Factoring in reduced air infiltration and thermal bridging, they can achieve effective R-values above R-40.
- Habitat for Humanity Likes It: If a non-profit with volunteer labor uses it, it has to be affordable and simple to construct.
Want to learn more? Connect with Ken on LinkedIn.
Connecticut Passive House and BuildGreenCT extends our appreciation for Tremco’s Annual Supporter Sponsorship and to Ken Lynch for generously sharing his time and expertise.
Visit the Connecticut Passive House Community page for more details and sign up to stay connected.