Building A Cob House-Follow Up With the Mullenneaux's

In early November I wrote a post on "Building a Cob House" about the Mullenneaux family, and their personal cob building community story. The responses from readers were fantastic and inquisitive, so I felt a follow-up was necessary. I reached out to Hap and Lin Mullenneaux with questions readers had asked and how it felt to be living in their new cob house the past month. They happily obliged and also offered to serve as a contact for anyone else interested in cob houses. I hope you enjoy and learn from their responses as much as I did.

GB: With your cob home finished, how does it feel to be living in a home that you created solely with your own hands (and feet), especially with the help of Fairfield (Iowa's) supportive community?

HLM: We have been living in the house for one month. It feels more like a part of nature than a conventional house. As something natural, it is easy to accept it as it is. While there are some things that aren’t finished, we are beginning to realize that this house may never be finished because that is a static condition and this house is alive. We do look forward to running water inside and taking baths at home, coming as soon as the pond fills. Since summer ended we have missed our outdoor shower.

Loft Bedroom. The ceiling is bamboo matchstick blinds over reflectix. Photo Credit: Hap and Lin Mullenneaux

GB: What specific environmental benefits have you noticed in your new cob home?

HLM: In building this house we used much more “waste” than we created. Now our use of energy and water is a fraction of any house we have lived in before. We use rainwater from the roof. We heat with wood from the scrap pile at a nearby sawmill. Our total monthly housing costs are under $100, mostly phone and internet.

Cozy Kitchen-Photo Credit: Hap & Lin Mullenneaux

GB: In my previous post, I received a question regarding cob homes' flexibility and durability for various climates. Can you answer that comment, especially in light of Iowa's notoriously cold winters, wet springs and hot summers?

HLM: At this stage of our experiment the jury is still out. The season in question is winter. Cob walls give you excellent thermal mass. Heat them and they will radiate that heat back to you over time. But what happens when there is a sub-zero wind chill hitting the other side of the wall? Stay tuned!

GB: Are there any challenges you've noticed since moving in?

HLM: Balancing the heat was a challenge because we put the woodstove by the stairs. We are closing it in so that the heat spends more time downstairs. Condensation was an issue at first. We made the house very tight and there was still cob and plaster drying when we moved in. Add the vapor that we contribute from cooking, etc and you have high humidity. This is becoming less of an issue as winter progresses, but the interior plaster absorbs moisture easily and down the road we may cover it with something less permeable.

GB: So, if someone were interested in building their own cob home what insights, resources and advice would you give them and why?

HLM: In a climate with real winter you need to use every bit of the building season to finish a cob house before freezing begins. Keep the design small. Have the foundation and stem wall ready in the spring. Do the roof first on either permanent or temporary posts. We had to work hard to protect our walls before we got the roof on. Enjoy the process and encourage everyone to enjoy it with you. Cob is not meant to be done alone. To give cob a fighting chance in cold weather, do everything you can to help it. We made the house tight with good windows that are strategically located. We insulated the roof properly. We probably should have done more to insulate our stone stem wall. Keep the cob walls thick. In places where we sculpted seats or niches into the wall the thin wall tends to be cold and damp. Finally, don’t let heating be an after thought in a cold climate. Make sure you will have heat where you need it with proper placement of the woodstove or other heat source. Some folks who built a cob house in south central Iowa said that their home was a bit chilly when the woodstove was located on the north wall. The next winter they moved it closer to the middle of the house and were much more comfortable.

Be sure to get some hands on experience before you start your own project The workshop that we took at Cob Cottage was a blast. http://www.cobcottage.com/

Here are more great teachers we have met:
http://www.housealive.org/
http://www.emeraldearth.org/
http://www.cobincornwall.com/

We are happy to answer questions and share our experience via email: haplin[at]gmail[dot]com

Thanks for doing this, Grace.
Hap & Lin Mullenneaux