What’s a ‘cob’ house?

Published 4:43 pm Wednesday, January 9, 2008

Jai Boreen not only lives on the land, he lives surrounded by it.

His San Juan Island home is built into the side of a rock outcropping.

The home is heated by a rocket stove, a special wood-burning stove. Kale grows on his sod-covered roof. The wind blusters outside, but the inside of his home is cozy, dry and quiet. It’s warm enough and light enough for Boreen, an accomplished gardener, to tend to an array of cacti and succulents. In the summer, the home is pleasantly cool, he said.

The walls and floor are made from an adobelike mixture called “cob” made of straw, sand and clay pulled from the surrounding land. Cob is an English word that means lump, and indeed, this home was built by melding and sculpting loaf-sized lumps by hand. The cob dries, leaving a thick, strong wall that resists rain. The outside and inside of cob homes are typically sealed with plasters, lime washes or milk paint.

Cob sounds like the material the three little pigs ought to avoid, but these homes are sturdy, cozy and structurally sound in a Northwest climate, said Joshua Jayson Boreen, Jai’s son and the builder of the home. This style of building dates back centuries, he said, although with the exception of Southwest adobe it’s new to the U.S. Thousands in Great Britain live in cob homes, some of those homes have been lived in for more than five centuries.

Cob building in this area is limited to a handful of free thinkers. Boreen and his partner, Kirsten Carter, run a professional cob building business called Earthen Culture, based on San Juan Island. The Ancient Earth School of Natural Building, started by another couple in Freeland, offers summer workshops to the public on natural building techniques, including cob.

Natural building techniques are gaining some acceptance locally as more people become tuned into green building practices, said Christopher Schwarzen, a Snohomish County spokesman. Developers have expressed interested in alternative building techniques, he said, and the county also would like people to consider techniques that could reduce the carbon footprint.

“It’s cropping up in more and more industrialized countries, and you’re going to see it in Snohomish County as more people begin looking for alternatives,” Schwarzen said.

It can be hard for westerners to get over the idea of a house built of earth, but there are advantages, Boreen said.

The materials for a cob home are inexpensive, readily available and plentiful. It’s hard to get cheaper than dirt. Jai Boreen’s 800-square-foot hut cost $35,000 to build, most of that was spent on labor. Nearly all the materials were drawn from nearby fields, including the wood that makes up the roof. Owners willing to build their own cob home can do so for little money and a lot of hard work, Jayson Boreen said.

Cob homes can look and function as modern or as rustic as the builder chooses. Boreen worked on a home in Monroe with high-speed Internet access and other modern accoutrements, which he said was appraised at $250,000. Although Boreen’s father chooses to live a simple life, cob homes can have wiring and plumbing embedded in the walls, as well as doors, windows and ornamental embellishments such as glass.

Cob homes have an artistic, free form quality to them. Cob can be shaped, molded and sculpted into virtually any form. Builders fashion curved walls, arches, custom window seats, shelves, platforms, crannies, nooks and fireside benches.

Cob building also is inherently green. The materials are nontoxic, recyclable and often close at hand. Cob walls do not function adequately as an insulator in the Northwest, but the walls, once heated, can stay warm for days, Boreen said.

Cob building is relatively simple and requires few tools. It’s essential to site the home properly and build a solid foundation and a good roof, he said. Cob builders often talk about keeping the “feet” and “hat” of the building dry: deep roof eaves to protect walls and a foundation that doesn’t let water through.

Time shows cob homes can hold up as well as other homes, but many building inspectors have been reluctant to approve them because they’re unfamiliar, Boreen said. It may be easier to get a permit approved for a home built with a wood frame and filled with natural materials rather than a project where the cob walls are the load-bearing walls, he said.

In Snohomish County, homes built with natural techniques are given no more and no less scrutiny than homes built any other way, said Greg Morgan, deputy director of the county Planning and Development Services. Natural building projects have to comply with current building codes.

“The codes are intended to protect individuals from fire and life safety issues,” he said.

The county approved a permit for at least one home now under construction in Monroe that uses natural building techniques. The home is built with post-and-beam construction, but instead of wallboard and insulation, the builder is using straw.

Eli Adadow and his wife, Marta Mulholland, have run Ancient Earth School of Natural Building in Freeland for six years. Adadow became interested in natural building techniques after traveling to Asia and Africa. The simplicity and practicality appealed to him.

“They practice a way of life that is unknown to us because we do have Home Depot,” he said. “If our door breaks we buy a new one. If something breaks on their house they fabricate something from scratch.”

The workshops the couple teach in the summer draw people interested in green building and those who want to build inexpensively. Natural building encompasses a range of techniques and materials, including living roofs, earthen floors, straw bale and cob construction.

“Natural building is the greenest form of green building,” he said. “When most people think of green building they think of things like solar or wind power, or bamboo flooring, things that are fairly expensive. People aren’t sure they can afford to do green building. Natural building is not expensive. It is labor intensive, but there are ways around that.”

Enlisting family and friends to build is one way to lighten the load, Adadow said.

He has noticed an uptick in interest in natural building techniques recently, fueled by people interested in green building. He expects interest to grow.

“Natural building is still a very small part of the consciousness,” he said. “It’s a like a small revolution going on within the country.”

Reporter Debra Smith: 425-339-3197 or dsmith@heraldnet.com