Homebuyers in today's business climate expect homes with more than superficial value and with beauty that's more than skin deep. Buyers are looking for long-term benefits like lower energy bills and maintenance costs. This is a major reason why Insulated Concrete Forms (ICFs) are gaining popularity with builders. The inherent strength and solidity of concrete and the insulating value of foam give ICFs several advantages in terms of energy efficiency, safety, and soundproofing.
ICFs are hollow foam blocks or panels stacked together and filled with concrete. Foam not only helps to form the wall, but it also provides insulation that’s built into the permanent structure. The two types of plastic foam commonly used in ICFs are expanded polystyrene (EPS) and extruded polystyrene (XPS); XPS is slightly more resistant to moisture and air and has a greater R-value. Some ICFs contain small, pre-assembled blocks that lock together like LEGO® bricks, while others use panels or planks that are connected with brackets or ties.
Advantages
With built-in insulation and heat-absorbing concrete, ICFs create an exceptionally airtight and energy-efficient home. Concrete is a thermal mass material, which means it absorbs and stores heat and then releases it when the surrounding air is cooler. The thermal mass of ICFs helps to mitigate temperature swings in the home, eliminating drafts and cold spots. Because of this improvement to the building envelope, a home built with ICFs needs 30 to 40% less energy for heating and cooling. Smaller HVAC equipment can be installed to heat and cool the home, reducing construction costs by $500 to $2,000.
The tight, sturdy construction of ICFs enables the exterior walls to withstand hurricane winds and earthquake tremors. ICF walls also muffle noises better than framed walls, making homes quieter and more comfortable. Moreover, because ICF walls are made of concrete, they're more fire-resistant than framed walls.
Installation
Although building with ICF walls is similar to conventional homebuilding, it requires careful planning to determine where to locate openings for windows, doors, mechanicals, plumbing, and electrical wiring. Minimize running services through the concrete walls as much as possible. Also, choose a footing that’s engineered to accommodate the ICF system and is designed for increased loads.
Once the footing is installed, stack ICF blocks, panels, or planks. While laying the foam units, install reinforcement bars per the manufacturer’s or engineer’s specifications. The specifications for installing rebar vary depending on the type of ICF system and the region of the country in which the home is built.
Once the skeleton of the walls is in place, brace the walls temporarily to keep them straight when concrete is poured. Pump concrete in even layers. After a curing process of a few days, all temporary bracing can be removed, and construction on the house can resume. With all ICFs, you can easily fasten interior finishes, such as drywall, and exterior finishes, such as brick and stucco, onto the wall with the same ties that are used to connect panels or planks together. Channel electrical wires through the foam on the surface of the ICF walls.
By using ICFs, builders can construct stronger, more energy-efficient homes that reduce labor and construction costs and keep homeowners safer and more comfortable. For more information about Insulated Concrete Forms, visit the Insulating Concrete Form Association site.
More Best Practices® for building durable foundations can be found in the following online training courses from BuildIQ University:
Foundations: Basements & Crawlspaces
Foundations: Slab-on-Grade
Water Management: Basements & Crawlspaces
Water Management: Slab-on-Grade Foundations
