Michael Riccitelli always wanted to try straw bale construction.

So when his wife, Christine Farnandis, a yoga instructor/therapist, suggested he build her a yoga studio behind their house, the professional engineer did some extensive research to convince himself and her of the opportunity this presented.

Both are concerned about environment. He was drawn to the insulating quality of straw bales. She was drawn to its minimal impact.

"It feels good," Riccitelli says.

Eco-friendly

design features

Natural is the underlying theme of straw bale construction, with the use of minimal wood compared to standard construction. Any wood framing is done with FSC-certified and reused wood. For this project it was mostly post and beam with straw infill.

FSC stands for Forest Stewardship Council - which assured the homeowners that the lumber has been sustainably harvested. That means the truck used to haul the wood from its point of origin to its destination travels less than 500 miles and the product is found regionally/locally as well.

"This way you are supporting local mills and businesses like Spaeth Lumber rather than big box stores, using less fossil fuel, and your money stays in the community in which you live," Riccitelli says.

Some of the wood came from 120-year-old fir planks salvaged from a local barn in Sheridan. Riccitelli trimmed around the windows, skylight and ceiling using FSC hemlock and/or plywood.

The walls consist simply of straw bales that came from a local grass seed farmer. Bales are typically 18 inches thick and when covered with one inch of plaster on each side, have an insulation value around (R40).

Soundproofing is another bonus - a plus for this couple who live along a very busy street. Straw is also completely recyclable.

"This part of the construction was quick, easy and inexpensive," Riccitelli says.

Once the wood framing was done it took just one and a half days to put the walls up, windows in, and insulation (needed for the ceiling mostly). For this 500-square-foot yoga studio they spent roughly $600 for the walls rather than the thousands it would take for stick built.

Plastering on the other hand takes much longer. Preparing to plaster took Riccitelli about 3 weeks working 4 to 5 days a week to cover the straw with mesh, wire, cutting out holes for outlets, and windows. Plastering takes three coats inside and out for a total of 6 visits from that subcontractor. Each layer has to dry between 10 to 14 days before the next one is applied.

Materials needed for the plaster include St. Astier natural hydraulic lime, sand, water and straw.

Denim insulation comes from old blue jeans. The raw material is primarily scrap and waste material from manufacturing blue jeans and other cotton-based textiles. This helps the environment by keeping it out of the landfill, and is a natural alternative to fiberglass insulation. Riccitelli estimates the insulation value at R21 for 5-inch thick material, R30 for 8 inch. And you can handle it without gloves! The downside is the expense, but for a small space, he says, it's worth it.

All windows are energy efficient Low-E glass which provides protection against heat gain and heat loss, condensation and fading. Windows that are operable, a ceiling fan and solar circulation fan keep the air indoors fresh and healthy.

Paints and sealants used in this project were all low/no VOC (like Safecoat) that significantly reduce harmful fumes. The project required minimal flooring material, using a combination of dyed concrete over radiant-floor heat and in some places marmoleum (made from cork, linseed oil and other natural substances.)

The roof is made from 100 percent recyclable metal with high reflectivity, reducing the 'heat island' effect and energy costs (20 percent reduction). Metal is also the best option for rainwater harvesting (a subject I'm saving for another article.)

Most, if not all, of the eco-friendly materials for this project came from Your Green Home located in downtown Corvallis.

Take home message

Here are the most asked questions and answers about the yoga studio from this year's Northwest Earth Institute tour in August.

Q: Was the city permit process difficult?

A: In spite of the headache with the review and permit processes (straw bales are allowed in Appendix M of the Oregon Residential Code) and the fact that most contractors know little about this type of construction, don't let these things steer you away. The inspections have been going great.

Q: What was the cost difference?

A: Cost was 20 percent less than traditional construction, based on the fact that I'm doing a lot of the work.

Q: Am I concerned about water getting in and rotting the straw bales?

A: NO! However there are certain things during construction you have to pay close attention to. The floor was raised one foot above 100-year flood plain. Water tightness - no roofing issues overlooked. Go overboard around any penetrations - super flash around windows and where you put in exhaust vents, bathroom vents, etc. - and extend roof overhangs (2½ feet on all sides minimum).

The take home message is this. "Using straw bales is just ONE of the alternatives to get away from traditional stickbuilt (wood frame) construction - to go along with an environmental conscious," Riccitelli says.

"We need to explore more."