Building An Earthship In Darfield, B.C.

We are a family of five living in Darfield, BC.
Our house is six hundred square feet in total and we are feeling cramped.

We have decided to build an earthship!

So starts the adventure ...

Friday, January 9, 2009

We Visited the Potter Earthship (Chris' take)

On December 15th we started our Christmas holidays!

In the next four days we traveled halfway across the country (4300km) to visit my family for Christmas. We averaged 1000 kilometres a day and the relief in the car was obvious by the time we pulled into Portland, Ontario! The kids are excited about visiting the CN tower the following weekend, but my excitement was our planned visit to the Potters the next day.

Knowing that we were heading to Ontario we decided to look into the Potter’s earthship. The Potters built an earthship about ten years ago just outside of Bancroft Ontario. We found out about it on the web at, and found out that they will give tours of their home if you arrange to visit them in advance.

That was enough for us!!! Before we left BC we phoned the Potters and arranged to visit them and their house on the 20th of December, the day after we arrived in Ontario. The weather as we traveled across the country was pretty good; no new snow and reasonable roads. Literally within an hour of arriving at my parent’s house it started snowing, and was still snowing when we went to bed.

Fortunately the morning of the 20th the sky was clear and we slowly made our way to the Potter’s earthship. Despite all of the research we have done preparing to build our earthship we had not yet actually set foot in one, so both Sandra and I were looking forward to seeing this house.

When we arrived Chuck and Pat Potter met us at the door and we all sat down at their kitchen table. We talked to them for a couple of hours and the conversation alone was worth the visit. The discussion ranged from gray water recovery to permitting the building to the nuts and bolts of tire pounding.

The Potters built their home over three years and were the actual builders of the home. In their words they built the home from cash on hand so they did not have to take on any debt, and they estimate they spent $45,000 dollars on their home. The only down side to building the home this way is that it took them over three years to finish!

Their house is approximately 2500 sqft and built using the methods and layouts described in the first two Earthship volumes. I am not sure if the third volume was written when they built. We visited on the second shortest day of the year; the inside temperature was in the mid-sixties and their only heating source was a wood burning kitchen stove that they use for cooking.

Our discussion covered numerous topics and here is what I remember …

Pounding Tires

The traditional method of filling tires involves a sledgehammer and lots of manual labour. Each tire is filled with earth and literally beaten with a sledge hammer until 95% compaction is achieved. I had researched a method of tire pounding that involves cutting the top sidewall off of the tire after it is placed in the wall. The removal of the sidewall allows the tire to be easily compacted with minimal effort. The Potters cautioned against this method as the removal of the sidewall means that the tires will not bulge as they are filled. The bulging tires actually interlock with each other such that a tire cannot be pulled out of a finished wall. The Potters also said that the initial engineering analysis done on these walls in New Mexico was very complementary of this interlocked stack of tires and said that it was structurally sound and made the tire wall very resistant to lateral forces. Cutting the tops off of the tires minimizes this interlocking and reduces the structural integrity of the wall. It looks like we will be pounding tires the hard way!

Floor Insulation

There is a lot of debate about the use of insulation under the floor of an earthship. The Earthship books written by Mike Reynolds are pretty clear that you do not place insulation between the earthship and the ground beneath it. The earthship relies on the constant temperature provided by the mass of earth underneath it, and insulation cuts the earthship off from this ‘thermal battery’. There is some discussion in Canada that due to the colder climate insulation should be used. Chuck Potter was very emphatic on this point … do not place insulation between the building and the ground. I agree with this.

This lack of floor insulation can result in cold floors. We discussed the use of a radiant floor heating system (or radiant wall) to resolve this issue. This is something I would like to investigate more.

Wall Finishes

The Potters originally planned to use stucco on their walls. They wound up using a cement/sand mixture. They felt that stucco would require more maintenance over time. They are quite happy with this wall finish. They used cistern paint on the interior walls as this paint also provides the vapour barrier.

South Facing Windows

The Potters have never installed blinds on their windows. They estimate they lose 5-10 degrees of warmth overnight.

This covers off what I remember talking about. I will add more details to this post if and when I think of other things.


strawgeek said...

Hi Chris & Sandra,

Sorry I missed you during your recent trip.

Regarding floor insulation.... my opinion
is that adding it is a good idea.

Basically, any surface that is below
your comfort zone (say, 18 C) is a
heating loss. So a cold floor is
not good. You want to avoid this.

I will send more details by email.

John Kingsley

Anonymous said...

Hi, Chris & Sandra:

I told my mother about your visit to the Potter's Earthship in Gilmour, and she remembered reading about their "house built of tires" in the Bancroft Times several years ago.

She was fascinated by your project and asked me to keep her updated on your progress.

Cheers, Jan
P.S. Hi, John!

Chris said...

We're happy to provide a forum to reunite old friends....

Anonymous said...

I am currently in the planning stages of building an earthship near Winnipeg. I am curious If you have decided to install the radiant floor heating as backup. I too was debating radiant floor heating. I am currently thinking to go with Solar hydronic heating without floor insulation. What are your thoughts/advice?

Thank-you in advance,

Tara & Ben.

Chris said...

Hi Tara and Ben,

I discussed some more of my conclusions with regard to floor insulation at the posting ''.

The book I refer to by Rob Roy is an excellent read, and addresses this issue.

I did not in the end insulate under the walls of the earthship like I originally discussed in the link above. I found there were too many practical issues in doing this that I was not prepared to address.

However, I do plan to insulate under the floor (except for planter space and utility areas), and I will use the thickness specified by my local code (R10 without looking I think).

Even the Earthship Biotecture group is addressing increased insulation with their new ideas referred to as 'thermal wrap'. To be clear though they are still against floor insulation.


Anonymous said...

Thanks Chris!

The info is much apreciated.

What about radiant floor heating?

Tara & Ben

Sandra said...

Radiant floor heating ...

We are also thinking of using radiant floor heating.

We hope to have an option to use solar heated water for this ... but have not really thought about it enough.