A Surprising Innovation in Home Construction: The OA Awesome Wall

"“If it isn’t geared toward thriving, it’s going to fail.”"

One of the most essential choices homebuilders will make in new construction or a major remodel is the exterior wall. On the outside, this is the “face” your home shows to the world (or at least to your neighbors). Called “exterior cladding,” its primary purpose is to protect your home from exterior elements, with aesthetic elements also clearly crucial. Common exterior cladding options include brick and mortar, stucco, vinyl siding, wood siding, and metal cladding.

But what is behind that pretty exterior cladding? Depending on how it all comes together, it can make all the difference in the world between a comfortable, dry, and durable home—and one that is drafty, wet, and moldy. From the interior drywall to the exterior cladding, there are many variations of how these layers of the exterior walls come together. For both remodels and new construction, this might be one of the most essential components in which builders need to be experienced. And, it happens to be one area where most homeowners would not know the right questions to ask. So, for all the builders out there: wouldn’t you prefer an awesome wall?

What’s the Awesome Wall?

The OA Awesome Wall was developed by Otogawa-Anschel, a Minneapolis-based, award-winning design and build firm devoted to green building and urban living. According to OA’s owner, Michael Anschel, the wall is designed to be particularly “difficult to screw up.”   Performance, resilience, the ability to be installed in multiple scenarios, and its built-in redundancies to account for inevitable, real-life errors made in the field are what make it a uniquely preferable external cladding system for any residential building project.

The OA Awesome Wall consists of several layers of independently manufactured products, all of which work together to make the wall “awesome.” The innermost layer is wood 2 X 4’s. Next, moving from inside to outside is a two-inch layer of polyisocyanurate (rigid foam insulation also called “Polyiso”) bonded to OSB (oriented strand board, a type of engineered wood similar to particleboard), which, according to Anschel, “comes with an impregnated surface which is this [particular] product’s waterproofing system.” Polyiso has a high R-value compared to other materials: a two-inch thickness has an LTTR (long-term thermal resistance) value of 12.1. Other positive attributes of Polyiso include moisture-resistance, good stability, and recycled content. (From PIMA, the Polyisocyanurate Manufacturer’s Association: “Many facers on Polyiso products contain up to 100 percent recycled materials.”) Anschel adds that one advantage of this Polyiso bonded to OSB product is that it is lightweight and can be installed by a single worker with a pneumatic nailer, saving installation time. 

The Polyiso boards are taped into place with a Zip-System Tape, a product which Anschel says forms an excellent, smooth bond—particularly around window frames—and does not stick to itself as often as other products.

Next is an additional waterproofing layer called Benjamin Obdyke Home Slicker. Technically a ventilated rain screen, this layer adds space between the Polyiso and the final layer of external cladding. The vertically channeled, three-dimensional matrix of the home slicker leaves plenty of room for water to drain and evaporate away and air to circulate in all directions so that any water that gets behind the outer cladding of the wall dries out quickly. This is key for mold prevention.

On top of the rain screen, there are furring strips, to which the outermost layer of the OA Awesome Wall is secured: a solid cellular PVC (polyvinyl chloride) product, an example of which is “Celect,” by Royal Building Products, used for both cladding and trim. “Celect is warmer in the winter, cooler in the summer, and greener all year long. In addition to being completely re-usable and 100% recyclable, it provides an R-value that’s twice the thermal value of any other comparable material in the market. In other words, it’s as much of a renewable investment as it is a renewable material.”

Anschel calls the cladding a “very stable form of PVC,” by which we can assume he means chemically stable because one crucial aspect of this final layer is that it “moves,” i.e., expands and contracts according to various forces of nature, including temperature and moisture content. Its movement and the spaces reserved in its installation (e.g., the 90-degree angled vertical corner trim that overhangs the cladding and covers space allowed for the product’s expansion) assure adequate ventilation behind the cladding and around windows and doors. The system’s solid cellular PVC cladding carries a 25-year guarantee against 5 percent fade.

The final element of the system is Sierra Pacific windows. These are vinyl frame windows in which all of the vinyl remains in the frame, thus concealing what many consumers find unattractive about vinyl windows. You’ll find extruded aluminum on the outside and on the inside, natural wood that can be painted or stained.

How Awesome is Awesome?

Moisture in the walls in any home can lead to mold growth and poor indoor air quality. The redundancies in moisture control in the OA Awesome Wall guarantee that moisture and mold are minimized, and air quality maximized.

In a remodeling project in Minneapolis, a city noted for its extremely cold and dry winters and hot and humid summers, Anschel added about 2,000 square feet to an original 1,500 square foot house for a total of about 3,500 square feet and enclosed the entire house in the OA Awesome Wall. He estimates the home had about nine air exchanges per hour (ACH) before the remodel and about one ACH after. (A rule of thumb in a recent Rise article on energy-efficient ventilation systems: "If the house has less than 3 ACH, it is reasonably airtight and may need a ventilation system." A drafty house may have an ACH of 10 or more; a passive house may have ACH's in the 0.6-1.5 range.) So, this wall comes close to doing what a passive house can do in terms of the tightness of the home. While it does not come close to a passive home wall's R-value of about 60, with an R-value of 28, it is still significantly better than the residential energy code for all climate zones.

Anschel says, "you could put [the OA Awesome Wall] together 40% wrong, and we would still have a ventilated rainscreen. And that, to me, is key in ensuring that that wall can resist any rot moisture accumulation over the next 100 to 200 years. So, we call it the OA Awesome Wall, a 200-year wall because making that wall fail at this point becomes incredibly hard, even with people making mistakes along the way."

Costs and Benefits

Anschel expects the home's annual heating bill to be less than $500. How does that compare to average? According to tripsavvy.com, "In Minnesota, the heating season is from November to March. For large, single-family homes, bills can be as high as $500 a month when it's frigid but average more around $400 during warmer winters." That means the heating bills will be only about 20 to 25 percent of average—or a 75 to 80 percent savings. On the cost side, Anschel says it costs about 16 to 17 percent more than standard construction. That would make for a pretty reasonable return on investment.

Bottom Line

Less potential construction/installation error, less chance of mold growth, much more energy-efficient, more durable, and $500 per year vs. $500 per month in heating bills: pretty awesome. And last but certainly not least, Anschel has not put any patent on the OA Awesome Wall, preferring to promote it as much as possible, without any compensation, to demonstrate that "green" building is just "high quality" building. Now that's awesome.

Article by:

Donna Pols Trump

Donna Pols Trump’s work has been published in literary magazines and online. She has received several Pushcart Prize nominations. Donna’s education includes degrees in Biology and Physical Therapy and a host of writing classes taken and taught at The Loft Literary Center in Minneapolis. Her short story “Portage” was selected by judge Anne Tyler for first prize in a 2018 contest sponsored by december magazine.