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Why the Roof is the Foundation

It was a very blustery day in Bend today, with winds gusting up to 40 mph. But anyone who lives and works in Bend is used to the area’s quickly changing weather conditions–from 70 degrees and sunny one week to 50 degrees and raining the next. Rain or shine, snow or wind (or all of the above–completely possible on one day in Bend!), construction crews across town show up to work.

To the rear left you can see the roofing material now on the garage. To the right, the River Roofing of Bend crew is getting ready to place the steel roofing on the accessory dwelling unit.

The crew from River Roofing of Bend was on site at Desert Rain today, busy installing the metal panel roofing on the ADU (accessory dwelling unit). They completed the garage yesterday. To get video of the guys I climbed up onto the roof of the main home (you’ll find the video at the bottom of this post). You can really feel the wind from a rooftop! After an exhilarating hour up there, I climbed down to find a perfectly timed e-mail from Morgan Brown, president of Whole Water Systems in Seattle, Washington.

Whole Water Systems (http://wholewater.com)

Morgan is leading the way in engineering and managing Desert Rain’s water sustainability. Whole Water gathered more than two decades of rainfall data to develop a comprehensive water system–from rainwater collection (rooftops) to water storage (cistern) to water treatment (constructed wetland bioreactor)–that will allow Desert Rain to meet its water needs without having to rely on any water beyond that which is naturally available to it: rain and snow.

The roof design is an integral part of the home’s water use plan. In essence, it is the foundation of the water system. It is where precipitation first makes contact with the site, and, as a home being built to meet the Living Building Challenge, it is that water–and that water alone–that will provide for Desert Rain’s water needs. There must be enough roof surface area to effectively gather the needed precipitation. And determining roof area requires consideration of a variety of factors. Morgan explained the modeling used when calculating water needs for Desert Rain:

“Our engineer took into account the twenty year history of precipitation in Bend (average = 12 inches/year); lowest rain year (seven inches); amount of roof surface area available for collection; and range of anticipated user demand (occupants behavior, amount of water used). The resulting modeling suggested the need for a 30,000 gallon cistern to store enough water to get the occupants through the worst case dry spell without sacrificing on their intended average water use.”

Bear in mind that Barb and Tom’s intended average water use of 30 gallons a day per person pales in comparison to the national average, which is 98 gallons of water per person. Water conservation will come from a variety of areas, including Barb and Tom’s conscious behavior, high-efficiency plumbing fixtures, and a landscape that requires no irrigation.

The River Roofing crew installing the steel panels on the garage. May 2, 2012.

But to get the water we go back to where I started: the roof. “There are a variety of techniques that are employed to ensure the quality and sanitary nature of the drinking water collected from rain,” says Morgan. “First of all, the type of roofing material needs to be appropriate to assure that no unacceptable substances leach into the water.”

Jim Fagan, Desert Rain’s contractor with Timberline, said “It’s rolled steel from Kalama, Washington. They put an LBC [Living Building Challenge]-approved coating on it, and then place it on a big roll and deliver it to River Roofing here in Bend. And they actually fabricate the roof panels here. Steel is one of the things that LBC refers to as globally sourced. There’s a lot of recycled content in almost all steel now–there’s no virgin steel anymore. Steel is steel and we can get it from anywhere. But obviously if we can buy a coil of steel from somewhere in the Northwest, we’re going to stay close.”

This regionally sourced material serves to further the sustainability of the home and to create a dwelling that meets various aspects of Living Building Challenge standards, including respectful use of water.

I’ll close with a compelling quote from Morgan Brown about why water use and conservation is something we should all be thinking about–and why a standard like the Living Building Challenge is now more important that ever.

“From space, Earth appears as a water planet with two-thirds of its surface covered with the liquid. Unfortunately, this is saltwater and life on land requires freshwater to drink and grow the plants that produce our food. Of all the water on Earth, only three percent is freshwater and less than one percent is available to us in the form of rivers, lakes and aquifers that we can use to drink and grow food. To exacerbate the problem, we haven’t done a very good job of taking care of this one percent. With worldwide population at seven billion and climbing, we have been doing a miserable job of stewarding the finite resource we have available. Unlike oil and gold, we can’t live without freshwater. Necessity being the mother of invention, the near future will see drastic changes in how we use and value freshwater.”

– Morgan Brown, Whole Water Systems, Inc.

Video from the Desert Rain site today is included below. (Please excuse the wind noise; there was certainly no escaping it

Concrete Poured for the Cistern

Concrete being poured for the cistern's walls. April 10, 2012.

After weeks of building the form walls, the concrete was finally poured into Desert Rain’s cistern today.

Looking down into the cistern from the roof of Desert Rain (with thanks to Jason for climbing up for the shot!). April 10, 2012.

The men working on the cistern were in constant motion. A steady stream of cement trucks delivered concrete to the pumper. The concrete was then pumped dozens of feet up into the air through a pipe and back down to Andy, who guided the concrete into the wall forms.

Andy working the concrete pump. April 10, 2012.

Keith (owner of Central Oregon Concrete Construction)  and Mark followed Andy with a concrete vibrator, which vibrates any air out of the liquid concrete before it sets.

Keith (left) and Mark (right) using a concrete vibrator to settle the concrete in the forms. April 10, 2012.

They worked this way in three-foot increments—pouring and vibrating three feet of concrete at a time as they worked the perimeter of the cistern. They started the process again when they completed one layer.

The cistern is an essential part of Desert Rain’s “living building” design. Tom and Barbara may make one city water purchase to fill up the cistern when they are ready to move in. But after that, it will be a storage and filtration site for the precipitation (rain water and melted snow) that is collected from the roofs of the home and the accessory units. As stated in the Living Building Challenge 2.0 standards:

“One hundred percent of occupants’ water use must come from captured precipitation or closed loop water systems that account for downstream ecosystem impacts and that are appropriately purified without the use of chemicals.”

The cistern has three chambers. Water will flow from the roofs through downspouts and piping into an initial intake chamber; from there, the water moves into the largest of the three chambers, where it is stored before it moves to the third tank, where filtration takes place. From there, it moves into the home for use in everything you use water for in your home: drinking, cooking, showering, toilets, etc.

April 10, 2012.

After a day that saw nearly 160,000 pounds of concrete poured into the forms for the cistern’s walls, Barb and Tom are one step closer to achieving their goal of creating and living in a home that uses only the water that nature provides. We have a brief video of the concrete pour over on our Facebook site: https://www.facebook.com/desertrainhouse

Barb looks on as the concrete is poured into the forms for the cistern's walls. April 10, 2012.