Choosing Eco-friendly Foundations
Choosing the right, eco-friendly foundation for your upcoming building project here in the Fairbanks area is crucial to its longevity. Fortunately, there are a number of options for cold climate new home construction that can perform well despite the local weather and geological challenges, where we see everything from ground tremors to challenging levels of moisture to frequent freezing conditions.
Sorting through high-performance, Alaska-friendly foundation options for your home can be daunting–we are here to help. First, let’s look at the role your foundation must play in supporting your house: it must bear the building’s weight (vertical load); anchor the house against tremors or wind (horizontal load); protect the structure from soil moisture, and avoid movement from expansive soil or frost heaving. Your foundation must be protected from the elements and properly constructed to support your home (and fight heat loss) for the coming decades. To help you make an informed choice about your foundation, refer to our expert outline of some of your best environmentally sound foundation alternatives.
Insulated Concrete Foundations
ICFs or insulated concrete forms are typically made of rebar surrounded by a foam layer around the outside. This configuration uses light but rigid foam “bricks” which are designed to connect and interlock. They help to form the poured in concrete while it cures and also become part of the structure, acting as an insulating material. This is a strong, enduring solution that avoids the possibility of rot. The ICF design helps decrease heat loss (to increase home comfort and lower energy bills) while limiting concrete usage for additional savings.
In the Fairbanks area, foundation footings and walls must be more than 40” below grade, which can be costly. A frost-protected shallow foundation, or FPSF, is an option if your area is permafrost-free. The foundation has been used in colder parts of Europe for half a century and it enables much shorter foundation footings to save money, energy, and natural resources. Insulation under footings is used for frost prevention and to limit heat loss from the structure.
Fly Ash Fortified Concrete Foundations
Fly ash, a “side-effect” of production at coal-fueled power stations, will normally end up in a landfill. Instead of disposing of the material, the fly ash can be used to replace up to half of the Portland cement that goes into the concrete mixture. This creates stronger, less porous concrete, which protects the supporting fortified rebar from corrosion. Fly ash also uses less water in the mix, which is a sustainable, eco-friendly practice and saves you money.
The CCHRC (Cold Climate Housing Research Center) has pioneered a truly adjustable foundation to deal with variable permafrost depth. In this design, a 2X4 sits atop a spread footer. If settling occurs as the frost melts, hydraulic jacks are used to push the footer into the earth, creating a space where foam can be sprayed in to fill the space. The system uses embedded soil sensors which alert the occupants to ground temperature changes, so they can respond by using a heat pump to remove ground heat. This option may be out of the range of most homeowners but the innovative idea is an inspiring one.
When properly chosen for your specific property and soil, and expertly built, these foundations can provide a comfortable, enduring construction with the lowest heating and cooling costs possible for Alaskans.