Insulated Concrete Forms
A home needs 30 percent to 40 percent less energy for heating and cooling if it's built with Insulated Concrete Form (ICF) walls instead of wood framing. 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.
With built-in insulation and heat-absorbing concrete, ICFs create an airtight and energy-efficient home. According to the Department of Energy, ICFs can cut up to 19 percent of enrgy costs. Also, concrete is a thermal mass material, which means it absorbs and stores heat, and 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, 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 also enables the walls to withstand hurricane winds and earthquake tremors. They muffle noises better than wood frame walls, making homes quieter and more comfortable. Because ICFs are made of concrete, they are more fire resistant than wood walls, as well.
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. As much as possible, you should minimize running services through the concrete walls.
When you're ready to start construction, choose a footer that's engineered to accommodate the ICF system and is designed for increased loads. Once the footer is installed, stack ICF blocks, panels, or planks. While you lay 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 wall is in place, you should brace the wall to ensure that it remains straight while you pour the concrete. Use a concrete pouring truck to pour the 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, you can build stronger, more energy efficient homes that reduce labor and construction costs and keep homeowners safer and more comfortable.