Earth-friendly homes can be 'super-sized,' too.

Tara and Jerry Wolf's straw bale home dispels one key notion. Building with straw doesn't mean you have to stay small.

"You can be earth friendly and still have your dream home," Tara said, looking up at the family's chalet-style home under construction southeast of Blue Creek. "We wanted people to realize a straw bale house doesn't have to be 600 square feet. It can be as big as you want."

And the Wolfs are going big: 8,000 square feet on three levels. Five bedrooms, four-and-a-half baths and a huge game room and great room.

And, it's all off the grid.

"We're doing it kind of over the top," Tara laughs. "It's kind of a 'Jurassic Park' thing."

But don't get the wrong idea, the spacious home is more than rustic upper crust. Tara said her goal is "an organic feel."

With sand from the Yellowstone valley, timbers from the hills of central Montana and straw from the irrigated wheat fields of a Denton ranch, they have certainly hit that target.

Building with straw was Tara's idea, says Jerry, a local contractor. But it didn't take much to win him over. His company, Millennium Homes, now specializes in timber frame and straw bale construction. She's a real estate agent with Rimrock Realty.

"I figured, we're surrounded by wheat fields," Tara said. "So, we can be a little earth friendly."

The concept so intrigued the Wolfs, that in the summer of 2002 they signed up for a class at the Yestermorrow Design/Build School in Vermont. That's where they learned the ins and outs of straw construction.


Hybrid house
There are two distinct techniques for straw home construction. The more traditional type -- the Nebraska-style straw home -- is reminiscent of the homes that dotted the prairies a century ago. That's the same technique used recently to build straw homes on several of Montana's American Indian reservations. However, because the bales in that type of construction are used to create weight-bearing walls, the homes are limited in size.

"If it's too large, the straw tends to sag," Jerry said.

The "hybrid" straw home, which the Wolfs are building, incorporates straw into a frame house. Because they don't have to worry about bales sagging, the sky's the limit on size.

"The straw bales are not structural," he said. "They're just fill for insulation purposes."

And insulate they do. Jerry says the 16-inch thick bales -- finished both on the interior and exterior with an earthen plaster or "stucco" -- provide an insulation value that ranges between R-50 and R-60, compared to the R-19 that is required by code.

Until the house is complete, Tara says, it will be hard to estimate how much that'll save them in heating bills.

"But they say it's less than half," she said.

Going green
The Wolfs, however, are banking on more than just straw. Passive solar and solar panels are incorporated into their home. The couple carefully positioned the house to get the maximum benefit from the sun, which washes in through a wall of windows on the south side. All told, there are 130 windows, Tara said.

"It took some homework," Jerry said, "and a lot of plotting."

Down at the "power house" -- a small straw-construction building that served as a test run for the main house -- solar panels on the roof charge a bank of 32 6-volt batteries that provide most of the Wolfs' electrical needs.

"On nice days, during the day, it'll run everything we need," Jerry said. "But when the inverter senses too much electricity has been used or there's not enough (sun)light, the diesel generator will automatically kick on."

In keeping with the earth-friendly premise, Jerry plumbed in two water systems. Sewage and the kitchen sink are discharged into the septic system, but "gray" water that flows from the showers and wash can be recycled for other outdoor uses.

"Recycled" describes several of the home's features -- from the Turkish double door they discovered in New Mexico to the Jacuzzi and cabinets that Tara's sister donated from a remodel.

When all's said and done, Tara expects their 8,000 square-foot house will come in under $300,000.

"But if we were to build it for someone else," she said, "it'd be more like the cost of a custom log home -- about $250 per square foot."

Do the math: that calculates into a $2 million house.


From the ground up
The Wolfs are sold on straw, and they'd like to clear up some misconceptions. In all their research, they've never come across problems with bugs or rodents. Secondly, the straw bales used for construction are packed so tightly that a wooden stud would burn easier, Jerry added.

As for rot, they say straw remains in excellent condition for centuries when kept dry. Someone recently cut into a century-old straw house in Nebraska, Tara said, and the straw inside the walls was just like brand new.

"The number one enemy of straw is moisture," Jerry said.

For that reason, Montana's semi-arid climate is ideal for straw house construction. Also for that same reason, Jerry uses a moisture meter probe to make sure the bales are dry before they go into the walls.

"I don't want any more than 12 percent moisture," he said.

Stacked like bricks on edge, the bales are secured with packing straps. Once the wiring has been threaded through -- "You run it right through the straw, without any conduit," he said -- the bales are encapsulated on both the exterior and interior with a stucco mix of clay, lime and sand.

The Wolfs use clay to make "earthen" plaster, which differs from the concrete plaster more typically used. Concrete plaster is harder, they say, but the earthen plaster is breathable and not so likely to crack.


Don't sweat the small stuff
From the get-go, the Wolfs learned that straw construction is conducive to modification.

At Yestermorrow, Tara said, "They told us, 'as you're building, you can change the design. Don't sweat the small stuff.' "

The couple started with a basic floor plan and adapted it as they went. The 9-foot ceilings they originally envisioned were bumped up to 12 feet because they hated to cut the support timbers down. Where bay windows would have added extra roof work and costs, they extended the walls out to where the windows protruded.

"We were trying to cut corners but we added footage," Tara laughs.

Permits, financing and insurance were issues they considered up front. Permits (aside from the standard septic permit) weren't a concern, because they live outside city limits. Nor was lending an issue, because they borrowed from family.

Insurance, however, was a concern. But, in the end, even that didn't pose a problem.

So what about finishing touches, like hanging artwork and installing electrical boxes? Pictures and lighter pieces of art can hang from fixtures screwed into the plaster, Jerry said. For heavier pieces or even cabinets, backboards are attached securely to the bales before the plaster is shot. As for electrical boxes, they're screwed onto a 2-by-4 stake that's jammed securely into the bales, also before the plaster goes on.

By LINDA HALSTEAD-ACHARYA lhalstead-acharya@billingsgazette.com.