Living Roof Helps Orcas Island Home Blend into the Landscape

This residence on Orcas Island is crowned with an extensive green roof from XeroFlor.
Photos: Terra Firma NW LLC

Orcas Island is a horseshoe-shaped island in the northwest corner of the state of Washington. With an area of 57 square miles, it’s the largest of the San Juan Islands, and accessible only by ferry. When a client approached him about building a custom home on the island, Justin Paulsen jumped at the chance. Paulsen is the owner of Terra Firma NW LLC, a general contractor located in nearby Eastsound, Washington. “We were hired directly by the owners to build the project from the ground up,” Paulsen notes.

The 3,400-square-foot home features 3,850 square feet of roof area, which is crowned with a living roof. The system specified for the project was a XeroFlor extensive green roof, which was installed on top of a PVC membrane roof manufactured by Versico.

The green roof system consists of a root barrier with a drainage composite, 1-1/4 inches of growing medium, and pre-vegetated sedum mats. The system was installed in the late fall in 2018, so many of the plants were dormant. Photos: Terra Firma NW LLC

“The roof system works well for the home, which is designed in the style of the Bauhaus school of design,” notes Paulsen. “The home features many linear design elements, and the green roof gives it a sense of blending in with the natural surroundings.”

It was only the second green roof Paulsen had been involved with, so he made sure to do his homework. He knew from experience that work on the island would pose logistical challenges, so he tapped a talented to team to help design and execute the project.

The Roofing Contractor

Paulsen wanted a skilled roofing contractor to install the waterproof layer beneath the green roof system. The Versico rep in the area, Ken Stillwell, recommended All Weather Rooftop Solutions, headquartered in Everett, Washington. The company, owned by partners Todd Severson and Greg O’Neill, typically focuses on commercial work, but this project was right in their wheelhouse. Severson knew the company had to plan ahead to ensure the everything went smoothly.

Crews from Terra Firma NW installed the green roof system. The sedum mats arrived on a pallet and were unrolled on top of the growing medium. Photos: Terra Firma NW LLC

“Working on the island was the biggest challenge of the whole project,” Severson notes. “We wanted to complete the project in one week, so we had to make sure we had everything ready to go. Everything had to be transported by ferry, so we had to schedule all of the trucks and make sure all of the material landed at one time. We just had to make sure we had all of the material and manpower on that ferry.”

The PVC roof system was installed over a plywood deck. Crews first installed two layers of 3.3-inch insulation to achieve an R-value of 38. Tapered insulation system was then added to ensure proper drainage. The insulation was topped with half-inch DensDeck Prime cover board, which was mechanically attached. A gray 60-mil PVC membrane from Versico was then fully adhered over the entire assembly.

All Weather crews also installed OMG SpeedTite roof drains with Vortex-breaker technology, as well as Solatube light tubes. The large skylight was installed by the manufacturer, CrystaLite.

All Weather Rooftop Solutions installed the PVC membrane to provide a waterproof barrier beneath the green roof. Photos: Terra Firma NW LLC

The sheet metal work was completed by All Weather on a second trip, with a smaller crew returning to complete the flashing and edge metal. The roofing portion of the project went smoothly. “Justin from Terra Firma was great work with, and our superintendent, Jeff Gale, did a great job quarterbacking it on our end,” Severson notes. “Everything went off without a hitch. It’s a pretty unique little structure.”

Paulsen agrees. “They did a great job installing the insulation and the membrane,” he notes. “The biggest thing we had to deal with after that was protecting the membrane from other trades. Our stonemason had to go back up on the roof and complete the chimneys.”

To preserve the integrity of the membrane after it was installed, Terra Firma crews cut a 20-mil pond liner pond liner into sections that were used to protect areas of the roof that had to be accessed by other trades.

Installing the Green Roof

After all the other work was completed on the rooftop, crews from Terra Firma installed the green roof system in the late fall of 2018. Paulsen had heard about XeroFlor from another contractor and did some research. He then contacted Clayton Rugh, director of XeroFlor America, to design and specify the system.

“I thought it was really top-notch system,” Paulsen notes. “I went to Clayton to document some other examples that had been installed in the area, and I pitched it to our client. Clayton did all of the functional engineering work on the green roof system and determined the soil requirements. The plantings by XeroFlor were sourced very close to the project site, which helps to ensure successful future growth.”

Photos: Terra Firma NW LLC

The extensive green roof system consists of a root barrier with a drainage composite, which is an open-flow zone of polymer coils with a bonded fleece fabric sheet. The drainage material was topped with 1-1/4 inches of growing medium, followed by 1-inch-thick pre-vegetated mats, which contained a mix of sedum succulents.

The pre-vegetated mats are installed just like sod. “They arrive rolled up on a pallet,” Rugh notes. “You just align the roll adjacent to the previously installed roll, abutting it tightly, and roll it into place.”

Terra Firma also installed the edge metal and rock ballast around the perimeter. “I was amazed at how simple it was to accommodate the green roof portion of the project,” Paulsen says. “Once the membrane was down, we knew we were rock solid and the house was well protected. The green roof portion was easy to install. I’d definitely do one again.”

Paulsen is proud to have this project under his belt. He can’t wait to see it in the spring, when the green roof is in its full glory.

“Terra Firma NW thrives on jobs that have complex and unusual requirements,” Paulsen says. “This job, from foundation all the way through the roof, presented numerous design challenges. We have a $2 million-dollar house under this roof. If I had to give advice to anyone doing a green roof, my advice would be: Don’t cut corners.”

TEAM

Architect:  Harlan Pedersen AIA, Orcas, Washington

General Contractor: Terra Firma NW LLC, Eastsound, Washington, www.tfnwllc.com

Roofing Contractor: All Weather Rooftop Solutions, Everett, Washington, www.allweatherroof.net

MATERIALS

Extensive Green Roof System: XeroFlor XF + GM Assembly, XeroFlor North America, www.xeroflornorthamerica.com

Roof Membrane: 60-mil PVC, Versico Roofing Systems, www.versico.com

Cover Board: DensDeck Prime, Georgia-Pacific, www.densdeck.com

Skylight: CrystaLite, www.crystaliteinc.com

Daylighting: Solatube, www.solatube.com

Roof Drains: SpeedTite roof drains, OMG Roofing Products, www.omgroofing.com

A Roof is a Building Owner and Homeowner’s First Line of Defense in a Storm

The Midwest has been battered by unrelenting storms this year. Last week, I spoke to a friend who had just returned from visiting mutual college friends in Minnesota. They experienced a strong storm during the visit, and while they were all sleeping, our friends’ house was struck by lightning. The acrid smell of smoke awoke them and the eight people (four of which were children) scurried outside in their pajamas, leaving all their belongings inside. The local fire department contained the fire to the garage, which is attached to the house. However, the smoke damage inside is so severe that the family of four is currently residing in a hotel while their house is professionally cleaned.

Stories like these are all too common recently and this one hit a little too close to home for me. It seems easier (and less scary) to think storm damage won’t happen to me when those who are affected are strangers on the news. However, according the Alexandria, Va.-based Independent Insurance Agents & Brokers of America Inc., extreme-weather events and natural disasters are becoming more prevalent. The organization reports that since 1987 there have been eight natural disasters with insured losses greater than $1 billion; before 1987, there was one.

Although the Greensburg, Kan., EF5 tornado that occurred in 2007 didn’t cost that much, it destroyed 95 percent of the town, which is scary enough. Greensburg is coming back as a model for the rest of the country—rebuilding stronger and more sustainably. Read about one of the town’s strong, sustainable projects—the BTI-Greensburg John Deere Dealership, which is a metal building featuring roof-integrated daylighting systems designed to withstand high-velocity impacts—in “Tech Point”.

About 550 miles to the east, an EF4 tornado inflicted $30 million in damage on the Lambert-St. Louis International Airport in 2011. To rebuild four copper domes that were the crowning glory of Terminal 1, airport officials opted to use copper-clad stainless steel, specifically because they wanted something beautiful that could withstand harsh weather. Read about the roof system in “Tech Point”.

The other night, a clap of thunder actually shook my house for what seemed like a full minute. I’ve always been the type of person that enjoys storms but, after my friends’ incident, I have to admit I feel less safe in my home. I immediately looked online to determine whether I should move to the basement and then I stayed awake until the storm passed to ensure my roof didn’t catch on fire. I think it’s time I look into a better, stronger roof.

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