Our foundation system has been certified by the Passive House Institute in Darmstadt Germany as a Certified Passive House Componant
Our foundation system has been certified by the Passive House Institute in Darmstatd Germany as a Certified Passive House Componant
R 47.7 Under the slab and around the perimeter of the slab
Tapered frost wing
Contrary to what you might hear from others, Passive House certified buildings can be built on any type of foundation. Insulated slab-on-grade foundations are usually the most cost effective, but we also offer full foundations, crawl spaces, and foam-free pier foundations, each of which can be detailed for Passive House performance and comfort.
Our proprietary system for concrete slab-on-grade foundations is a raft slab, which we call the SuperSlab. Made from borate-treated EPS (expanded polystyrene), the most durable and benign plastic foam for this location, we designed the parts and pieces to lock together like Lego blocks—protecting the concrete slab from thermal loss, isolating the interior from radon and water vapor, and acting as a concrete form—all in one system.
Once the raft slab insulation is placed, we pour an 8 inch steel-reinforced concrete slab—thick enough that separate footings are not required under point loads, polished and sealed as a finished floor, or covered with another material.
Our Ecocor SuperSlab foundation system is certified by the International Passive House Institute to be free of thermal bridging, with a U value of 0.12 W/m²K (0.021 Btu/hr ft² °F), ≈ R 47.7.
For projects where treading lightly on the land is a key concern, eliminating plastic foam is a goal, or access to the site is compromised, we offer a pier foundation system. Using helical piers--galvanized metal posts with an auger screw at the bottom, literally drilled into the ground—we minimize disturbance of the site. The floor is framed with deep I-joists and filled with dense-packed cellulose, with an airtight, moisture-repelling skin applied to the bottom of the floor system.
We use a small, insulated chase to bring utilities into a central location. The same insulated floor system that we use for piers can be used on an uninsulated foundation or crawlspace.
Our foam-free framed floor system uses 24” I-joists filled with dense-packed cellulose, with assembly insulation values of 0.070 W/m²K (0.012 Btu/hr ft² °F), ≈ R 83.3.
Let us be clear: YOU CAN BUILD A PASSIVE HOUSE WITH A BASEMENT! It won’t be the “practically free” storage space that typical 1950’s style construction provided, but our Passive House basements are also not cold, damp, or moldy like those 1950’s basements, and they can be used safely as living space. There is a cost to waterproofing and insulating the foundation to a degree appropriate for a Passive House, but it can be done—we know, because we have done it on multiple occasions--typically when the building site is sloped and the basement can be a “walk-out” on at least one side.
Check out our Passive House Components. Our Panelized Construction approach to passive house building is perfect for all high performance building applications.