We use top quality, eco-friendly materials.
It is very important to us that our projects are built with the healthiest materials available. Several years ago this meant our attention was focused on researching straw bale construction as a building method, but we have evolved since adopting the Passive House approach to building design and deciding that we wanted to build the highest performing homes available. We now use various materials to ensure a durable, energy efficient assembly—all zero VOC (or as close as possible), locally produced and from renewable sources when possible. We prefer to use simple, natural, minimally processed materials where appropriate, such as natural wood finishes, polished concrete floors, natural stone, porcelain tile and other classic, healthy materials.
All of our building systems are based around the concept of Vapor Open Construction. All building assemblies are susceptible to problems relating to moisture accumulation if they are not properly designed or built; as the assemblies get thicker, with higher levels of insulation, the risk only increases. We have designed all of our systems to be able to dry readily to the interior, exterior or both, while remaining airtight and watertight, for the most resilient, durable building envelopes on the market.
In choosing a product to use at the core of our building assemblies, we researched all available insulation materials. We were looking for a product that was non-toxic, with no VOC’s, that would redistribute moisture that accumulated within the walls, that didn’t change properties over time, and that had excellent thermal resistance. We found all of this in 100% mineral borate treated, fiberized cellulose insulation. We have our own heavy-duty blowing equipment and have developed specialized methods to accommodate our thick assemblies. It works well installed at high densities in our walls, floors and SuperRoofs, and it works well blown loosely into attic spaces. We do most of our insulating in our shop, and bring our equipment to the job site to finish the project.
For supplemental insulation in the Service Cavities integral to the Structural Layer, which are filled after mechanical and electrical rough-in work is complete, we recommend and use one of two products. When the project is close to us and we are doing more than just the exterior shell, we generally use the same dense-packed cellulose that we use elsewhere in the project, blown behind a porous, gossamer fabric known as Insulweb. For other projects, we recommend either dense-packed cellulose installed by others, or mineral wool batts, such as Roxul Comfort Batts. With the majority of the insulation in the Blanket Layer, on the outside of the Airtight Layer, the service cavity insulation is well enough protected that nearly any insulation product will perform as advertised.
While we seek to minimize the use of plastic foam, it is arguably a better use for oil than burning it in energy-wasting cars or homes. We use the highest quality material with the lowest global warming potential, EPS (expanded polystyrene), in our Raft Slab foundation system, and also to insulate on the exterior of doors and windows, where the additional thermal protection is warranted. The product we use is the only rigid foam rated for termite resistance, using a natural borate additive.
We love natural wood and use it where appropriate, but we mix in engineered material when it serves a specific function. “They don’t build them like they used to” is true, but if they had the materials we have available today, the story would be different. Engineered lumber makes stronger beams; engineered trusses make clear-spanning floors and roofs simple and save material; high-quality OSB, properly located near the warm side of the wall, makes strong, vapor-permeable airtight layer. Our “Blanket Layer” is supported with wood I-joists, with solid wood flanges and an OSB web, which are incredibly strong, lightweight and minimize thermal bridging. All of these items are produced within a few hundred miles of our shop.
Our primary insulation, 100% borate cellulose, is literally chopped newsprint. It turns what would otherwise be a waste product into high-performance insulation, resistant to pests and fire, with a chemical and physical structure that protects adjacent surfaces by safely and effectively absorbing and releasing normal fluctuations in moisture content.
Some of the most critical elements of our assembly are also some of the lightest in weight: the membranes and tapes we use for the Airtight Layer and the Weather Resistant Barrier. There is nothing currently manufactured in North America that performs these important functions as well as what we use: the top-performing air sealing products imported from Germany, made by Pro Clima and supplied by 475 High Performance Building Products in New York.
High Performance Homes require high performance windows and exterior doors. We have sought out the products with the best quality, best performing and best value, and can review the various options with you. Passive House windows and doors are different from typical American products. The exterior doors seal securely against air and water infiltration, and triple-pane glass panels perform even better than the well-insulated frames, so we usually recommend all exterior doors to be glass. Windows are never double-hung units, as they are too leaky for a Passive House. We use European tilt/turn windows, which operate like an inswing casement window and with the flip of the handle hinge to be open at the top, like a hopper window. This style is capable of sealing tight against air infiltration. We also use large fixed windows where appropriate. We have developed our own installation systems to ensure that the windows and doors perform at the absolute highest levels.
Borates are naturally occurring minerals formed from rocks and minerals containing Boron. Seawater also has naturally high levels of borates. Borates are mined around the world, with the largest mine located in the US near the town of Boron, California, in the Northwest Mojave Desert. More than 4 million tons were mined worldwide in 2007.
The primary use of borates is in impact and heat resistant borosilicate glass. They are also used to impart flame resistance to cellulose insulation, wood and cotton products, and furnishings. When heated, the borates melt into and protect the fibers by surrounding them with a protective glassy coating. Further heating of the borates causes decomposition, producing water as a byproduct.
Borates are less toxic than table salt. They are commonly used in cosmetics, medically as an eye wash solution, as a water softener, and in many other products as a neutralizing or buffering agent. Due to their fungicidal properties, borates are used in many natural products, ranging from green lumber treatments and mildew resistant paints to coatings on organic fruit to prevent mold. Borates are also toxic to insects and are used widely in integrated pest management and control.
All of these properties make borates the natural choice for use with clean, recycled paper that has been fiberized, to create fire-retardant, high quality cellulose insulation for dense-packing and loose-blowing into our projects.
Check out our Passive House Components. Our Panelized Construction approach to passive house building is perfect for all high performance building applications.