Waterproofing

The Art of Building: Part 1


The framing stage of building a new home, design by Heliotrope Architects. Photo: Jill Hardy

The framing stage of building a new home, design by Heliotrope Architects. Photo: Jill Hardy

What is the process of building a new home? How do we go from architectural designs to a completed work of art? For those interested in building a new home, we've simplified the process by highlighting major construction milestones, and we take you on a visual tour of a house we're building in Seattle's Capitol Hill neighborhood. Designed by Heliotrope Architects, the front facade of the house features a prominent "floating gable." Read on to learn about the beginning stages of building a new home. 


EXCAVATION

Excavation allows for utilities to be buried. Photo: Duane Robinson

Excavation allows for utilities to be buried. Photo: Duane Robinson

The first step in building a new home is to excavate the site. Excavating, or removing soil, serves several purposes: it levels the site; allows for below grade utilities to be laid, such as mechanical, electrical, and plumbing; and prepares the ground for pouring the foundation. Above, one of the main plumbing lines, the side sewer, is installed. 


FOUNDATION FOOTINGS

The concrete foundation footings of a new home. 

After excavating, laying subgrade utilities, and leveling the site, trenches are dug for pouring the foundation footings. Constructed of concrete and reinforced with rebar, footings support the weight of the house and prevent it from settling. If a house is a like a sculpture, the footings are like the platform on which it sits. The size and type of structure determines the depth, width, and placement of footings. In the photo above the footings have rebar protruding through the concrete, anticipating the next phase of construction, pouring the foundation walls. 


FOUNDATION WALLS AND WATERPROOFING

Foundation walls wrapped in waterproof fabric. 

Foundation walls wrapped in waterproof fabric. 

Next, the foundation walls are poured. The foundation walls transfer the load of the house to the ground. They also act as a barrier between the wood of the house and the soil of the earth. The oldest and simplest foundation walls were constructed using large stones. In contemporary building, foundation materials have advanced dramatically, but the concept remains the same. 

After foundation walls have cured, the exterior walls themselves need to be waterproofed in order to prevent water from seeping through the concrete. Above, a skirt of drain board waterproof fabric is applied to the exterior foundation walls, which protects the foundation from water. 


BACK-FILLING AND LEVELING THE SITE

The foundation walls, once exposed for waterproofing, now just peak up above the ground. 

All the exterior utility lines are laid and the foundation walls are constructed and waterproofed, then soil is brought in to bury the utilities and grade the site. An incredible amount of work and infrastructure becomes hidden beneath ground. 


HYDRONIC HEATING SYSTEM 

Vapor barrier, insulation, and radiant heating tubes are installed before the foundation slab is poured. 

Vapor barrier, insulation, and radiant heating tubes are installed before the foundation slab is poured. 

This home has a hydronic system for radiant floor heating, which is highly energy efficient. Above, the tubing is installed over insulation, which prevents heat-loss toward the ground. Because concrete conducts heat well, a concrete slab is then poured on top of this hydronic tubing. 


FRAMING

Framing is the next step in the building process. Here studs and headers form walls, ceilings, windows, and doorways. Then, the frame of the house is bolted to the foundation. Framing provides the structure to support the form of the house, it also creates an armature for the network of electrical and plumbing utilities to come. 


SHEATHING

Plywood panels attached to the framing sheathes the house.  

The plywood panels applied to the outer framing of the house are called sheathing. Sheathing strengthens the structure and serves as a base for exterior weatherproof siding. In the Pacific Northwest, an earthquake region, sheathing stabilizes the structure and helps prevent sheer forces from pushing and pulling the house in opposite directions. 


FRAMING THE ROOF

Cathedral ceiling with framed skylights.  

After the sheathing is applied, framing the roof begins. Above, manufactured trusses create the vaulted ceiling and the roof line simultaneously. Modified trusses are erected where skylights occur. 


ROOFING

The roofing stage. 

The roofing stage. 

The design of this house calls for two different kinds of roofs. On the left is a "flat roof" (actually, it has a slight slope to prevent standing water), and the right side is a pitched shingle roof. The main role of the roof is to prevent water from entering the house. The roof is also part of the "building envelope" or the physical barrier that separates a building from water, air, and heat. The Northwest is known for its wet winters and the roof is an important element in the overall waterproofing system. 

Waterproofing itself is a crucial and complex part of building, and the next post will focus solely on the various steps in the waterproofing process. 

THE LIVING FUTURE UNCONFERENCE: Biomimicry and the "Adjacent Possible"


Janine Benyus presenting at the Living Futures unConverence 2015, Seattle, WA

Janine Benyus presenting at the Living Futures unConverence 2015, Seattle, WA

The evening was breezy and brisk as we traversed Seattle’s downtown streets, heading for the Living Future 2015 unConference and its opening night events.  After mingling our way through the vendors section, we followed a man in a salmon costume into a large hall for the keynote address. Several elders from local Native American tribes began with a prayer. Then Sarah Bergman, director of Pollinator Pathway, described her a large-scale participatory project connecting cities, farmland, and national parks for bees and other pollinators.

It’s when Janine Benyus, the keynote speaker, took the stage that the tenor of the conversation shifted. With the earlier speakers we were still thinking about and existing in the present tense. With Benyus, we were in the future – the distant future – where biomimicry is a given and humans have restored balance to our natural systems thereby “creating conditions conducive to life.”* It was a paradigm shift, and that’s where she began her lecture, and it took me a minute to catch up. The thing is, Benyus is so far ahead of us that she’s actually inspired by the future. But, before we launch too far into that future, you may be asking, “What is biomimicry?”

Biomimicry is a term coined by Benyus herself that’s defined as “learning from and then emulating natural forms, processes, and ecosystems to create more sustainable designs.”* It’s using nature as a mentor. It’s “the conscious emulation of life’s genius.”* Studying the design of a leaf in order to create more efficient solar cells is an example of biomimicry. Or examining how Namibian beetles catch fog and condense it into water, then applying that design to a desert irrigation system. Benyus, a biologist, innovation consultant, and author, stresses that for any given design challenge – waterproofing, heating, daylighting – there are millions of organisms to learn from.

Benyus is also quick to point out what is not biomimicry. It’s not designing something and post-fabrication saying, “It reminds me of a whale.” This, Benyus sites, is convergent evolution, the development of similar features in different species. Biomimicry, on the other hand, is a design process that requires consciously consulting the natural world as a starting point. Additionally, using a renewable resource such as cork flooring, although it’s eco-friendly, is not biomimicry but bio-utilization. What about purifying water with bacteria? Again, not biomimicry but bio-assistance. Benyus explains that biomimicry is not using an organism itself, but borrowing a design idea from an organism.

Throughout her presentation, Benyus returned to a common refrain, “the adjacent possible.” It was the first time I’d encountered the “adjacent possible,” so I did some quick research. It’s a term introduced by theoretical biologist Stuart Kauffman that refers to an evolutionary process where biological systems are able to morph into more complex systems by making incremental changes – not great leaps. We did not go from walking to spaceships without first building bicycles, cars, and rockets. Or, to use a building analogy: you build a first floor with stairs, then you build a second floor with stairs, and finally a third floor. Each floor makes access to the next floor possible. You can get to the third floor because of the second floor. That’s the adjacent possible. You can’t see it or get there today, not directly. But through small steps, one next to the other, you can arrive at a vastly different place from where you started. It appears that Janine has applied the adjacent possible to biomimicry and can see into the future the elegant and innovative solutions to design and building challenges.

As I sat in the darkened hall, I began to wonder what that might look like. What are the biomimicry implications for the building industry, and how might the “adjacent possible” transform the field? What is biomimicry from a builder’s perspective? How might the “adjacent possible” help us innovate and envision the future of building? One obvious result of applying biomimicry to building would be an even closer collaboration with architects and designers. Because biomimicry looks to nature at all the stages of making – planning, designing, fabricating, evaluating – it’s easy to envision architects and builders communicating and cooperating at the planning phase. Additionally, with the utilization of biomimicry, the very nature of building may increase in technical and chemical sophistication. We could sub-contract biologists and chemists. There may even be a need for an on-staff biologist. Or, builders may borrow from birds the design for creating extraordinarily colorful plumage, and act more as scientists, combining molecules and chemicals, then overseeing as fibers organize themselves to create color by scattering light. At the very least, the fields of building and architecture will cross-pollinate with the fields of biology and natural sciences, creating a need for multi-disciplinary practitioners.

     Nanofibers of bird feathers create color by scattering light. 

     Nanofibers of bird feathers create color by scattering light. 

Furthermore, biomimicry could change not only the products and materials we utilize (that’s happening already), but our fundamental building systems and processes. To address the first point, our waterproofing products are advancing dramatically. Dovetail is currently building a net-zero energy home using a new product, Wet-Flash, which wicks moisture on the outside while allowing water vapor to escape from the inside, creating a waterproof yet breathable barrier. Sound familiar to human skin? That’s not just a coincidence, but a deliberate design choice, says Tom Schneider, the chemical engineer who developed the product. It’s not a far leap, then, to imagine a future of builders creating structures that are living and breathing and productive.

Addressing the point about process, we take for granted our current organizational structures and construction order of operation because they are tried and true. But, what could we learn from bee hives, a pride of lions, or a flock of crows? How could natural processes inform and improve the design of our building processes? Expanding on the idea of the adjacent possible, Benyus asked, “What did you make possible today?” As builders, we’re in the business of making. It’s an exciting moment when we can ask not only what did we make, but what did we make possible today.

How do you think biomimicry and the adjacent possible will influence design and building? How do you think builders will adapt in order to leverage biomimicry? What do you think is the adjacent possible for our field?

 

*Janine M. Benyus, “A Biomimicry Primer,” Biomimicry 3.8, 2014

FINELY CRAFTED WATERPROOFING FOR EXPOSED WOOD


The Pacific Northwest, in all its wonder and glory, does in fact experience extreme weather - long periods of winter rain followed by arid sunny summers (shh, don't tell anyone about our amazing summers). These weather extremes are particularly challenging for waterproofing exposed wood, which has the potential to soak up water and rot. Then, when it dries out, it can shrink and crack. In order to prevent water from damaging exposed wood, Dovetail employs several strategies: best practices (what we like to call "the fundamentals of building"); expertise built through years of applied knowledge and experience; and the highest level of quality and craft. 

The Challenge: Exposed wood subject to weather extremes - prolonged rain and sun. Repeat. 

The Solutions:

  • Paint: these deck posts will be painted, the first step in waterproofing. 
  • Ensure water does not become trapped. Within the design, allow for shedding and drainage.
  • Protect end grain: no exposed end grain. End grain that's exposed sucks up moisture and begins the rotting process.
  • Joints: fully glue all joints, which protects end grain and minimizes water retention
  • Minimize seams: when possible, build details out of one piece of wood
  • Reinforce seams: dado (cut a trench in the wood) and glue up wood details to prevent water from creeping in between two pieces of wood
  • Use exterior-rated plywood even in areas with minor moisture exposure.
  • Fasteners: stainless steel fasteners are superior to galvanized
  • Choose appropriate materials: clear Western Red Cedar, for example, is indigenous to the Pacific Northwest and thus acclimatized to Northwest weather. It's naturally resistant to rot, decay, and insect attacks. 
  • Sustainability: Cedar is a renewable resource, often harvested from some of the most sustainably managed forests in the world.

Architects and home owners: we'd love to hear about your experiences designing and living with exposed wood. How have your homes and projects held up?