High Performance Homes
Foundations
After grading and site prep a home's foundation is the first house component to be addressed. The primary function of the foundation is to keep out moisture and pests, and keep in heat. There are several different types of foundations from a full basement of poured concrete or cement block to simple wooden posts stuck in the ground.
The type of foundation chosen depends on two things, budget and subsurface conditions, and to a lesser degree, on local building codes and ordinances. A high performance builder can guide homeowners through the process of deciding which foundation is the best for their particular application.
A high performance home is most likely to have a full basement constructed of poured concrete or cement block. Concrete is an excellent material for foundations. It was first used by the Romans while constructing their empire 3000 years ago. Like the Roman builders, today's contractors plan their pour carefully taking into consideration the load that will rest upon it, its drainage capabilities, and the soil that will ultimately support it. After excavation, a footing of concrete is poured conforming to local building codes and ordinances. If the basement is to have poured walls, iron bars, known as rebar, are tied both horizontally and vertically on the footing within forms and then the mixture of sand, gravel, water, and cement is poured or pumped in the cavity between the form walls. Once the mixture cures, the process of hardening and strengthening, gaining compressive strength through the chemical process of dehydration takes place until it becomes a single, hard mass. If the basement is to be constructed from cement block, the blocks are stacked in an interlocking pattern and bound together with mortar, a specific mix of concrete, to the required elevation within the excavation and allowed to cure.
In a high performance home it doesn't stop there. The contractor, prior to backfilling around the foundation, will seal the wall to prevent moisture from penetrating and creating a mold problem. He may insulate the outside of the wall. This is important in regions where condensation accumulates on the inside wall. Moisture, both inside the basement and out is the single reason basements fail and with moisture, there will be mold. He will most certainly consider the slope of the property and the drainage potential of the surrounding soil. Where warranted the contractor may then tile around the foundation in such a manner so that rain water doesn't settle against the foundation wall. This moisture may eventually soak through the wall, or worse, freeze causing the wall to collapse inward. A poorly constructed foundation puts the entire structure at risk.
