The One Year Report: Life in a Cob House

by ziggy on August 21, 2010 -- 14 comments -- Follow


On July 11, 2009, I moved into my newly completed cob house. It’s now been over a year since the move-in, and there have been many learning lessons along the way. I’d like to present a number of those lessons here in my one year report of living in a cob house.

Here we go…

Day to day life

I don’t tire of staring up at the reciprocal roof, taking note of the feel of the floor on my feet, and noticing all the small construction details in the house on a day to day basis. The house still feels fresh. The size of the house is just about perfect for two — any smaller, though, and it would probably be too tight. (The house is about 200 square feet or so.) This year’s mud room addition will be invaluable, I think, and if I were to build another house, I wouldn’t consider doing without one. It will help in the cold of winter, and it helps to keep dirty shoes out instead of tracking in lots of extra dust inside.

Cleaning house

Speaking of dust, there’s a fair amount of it. You can sweep every day and come up with a decent pile of grit. I think that’s in large part due to the small space we live in: there are not many spaces for that dust to hide (and it’s certainly made visible because of a lack of carpet, too, of course). But I love to sweep, thankfully, and it feels good to “housekeep” like that, so it’s not a problem.

Storage capacity

Again, if I were to do it all over again, I probably would have installed a few more storage shelves — perhaps up above the south window and in higher places up on the wall. You simply can’t have enough storage space, especially when you have tools and candlemaking equipment and off-season clothes and travel items and camera gear and lots of books to store. But we make do quite well, and to be honest, we don’t have that much stuff. We are very careful about what we acquire. Living in a tiny space really forces you to consider what you really “need” around.

The earthen floor

The earthen floor is aging pretty well. It quickly lost it’s dark oily hue once the house was inhabited. Overall, it’s a fairly durable floor, but certain pieces of furniture do leave their marks. The rocking chair, for example, will leave runner grooves on the floor if not on a throw rug. Perhaps my mix was not “hard enough”, but overall the floor takes wear pretty well. I’m not sure how different a mix I could have made to improve the durability. (I think I used 3 sand : 1 clay : 3/4 cow manure.) One other thing: I did not make the floor to be perfectly flat, so some furniture needs minor shimming to sit steady, which is okay by me. It’s mostly a non-issue.

Interior plaster

There’s been no change here. It doesn’t dust very much at all, except for one certain shelf in the house, where I simply used too much plaster to even it out.

Exterior plaster

The house has been hit pretty hard by the rain in several thunderstorms this year. We’ve had winds so strong that rain has come into the north window, which is barely below the (2.5 foot deep) eaves of the house! I re-plastered the west wall very early this year, and it’s been hit again, but not hard enough to warrant plastering it again so soon. The north needs another coat pretty bad, too, but the east and south are less prone to rain damage. I imagine I will have to re-plaster those north and west walls at least every other year, depending on the severity of the storms we experience. It’s not a huge effort to do so, though. (I re-did the west wall by myself in a morning.)


Ahh… moisture. We live in a very wet, humid climate. Many of the homes here have high indoor humidity levels as a result. We finally bought a hygrometer recently and have been surprised to see that the indoor humidity is often hovering around 80% inside Gobcobatron! This is a concern, because with moisture levels that high, mold and mildew development is an issue.

We have had bouts of mold on the floor, especially when the humidity or temperature has shot up significantly in a short amount of time. We keep a spray bottle of vinegar around to clean any mold that does form. Thankfully, the e mold seems to form mostly on the floor, which is easy to clean. You can’t really leave anything on the floor, like boxes and the like, without expecting some mold during this time of year, especially. It’s good to have furniture that is raised off of the floor slightly, or that has legs.

We are currently investigating how to better ventilate the house and to keep air moving to keep this issue to a minimum. I really think clever ventilation is the key here. Keeping indoor humidity levels low is one of the biggest challenges in living in a natural home, especially without electricity! (We can’t exactly just go and plug in a dehumidifier…)



Installing a giant single pane window was a bad idea. Sure, you can get away with that in Oregon and other mild climates, but don’t even think about it in a cold climate where temperatures are frequently below freezing in the wintertime. On cloudy winter days, the south window is constantly wet with condensation, and we need a towel always in place to collect the water that collects at the bottom. It’s a real hassle to constantly have wet towels around. Same thing for the skylight, but even worse: the skylight actually drips (when the condensation isn’t frozen to the polycarbonate, that is). We use a “towel on a stick” to wipe down the skylight daily in the winter to keep it from dripping. You can bet that we are considering buying a second pane to insulate the skylight, and possibly tear out the south window next year to install a double paned one.

Keeping cool

In the summer, the house remains quite comfortable in high heat. This year, we’ve had long bouts of 95+ and even 100+ degree days (actually, it’s felt like way too many days with a heat index of 110 or even 115 to even count… ugh…), but despite those high temperatures, the indoor temperature has rarely crept past 83 degrees. More than likely, it’s been around 80 or 82 inside, and lately, in the mid to upper 70s (with the recent break in the heat). We have made a conscious effort to close the windows and shades during the heat of the day, only opening them at night when the temperature drops into the 70s.

We even put a tarp over the skylight so that the house is really dark. It’s amazing how much cooler a room will feel just because it’s darker than normal! I think better shading on the west wall of the house will actually help quite a bit, too: on really hot days, after the sun has gone down, you can actually feel the heat radiating off the west wall when you walk past it outside. I think a few grape vines are in order here. (Actually, the wood shed will block a fair amount of the late afternoon sun on the west wall, too.)


Keeping warm

Last winter was cold. Really cold. Inside and out. The rocket stove was a failure, so there was no truly adequate way to keep the house warm. The indoor temperature plummeted to below freezing before we were able to install a temporary wood stove. The temporary stove kept the house from literally freezing, but it wasn’t the most efficient setup, obviously.

I have much higher hopes for this winter, with the new Morso wood stove and the addition of the mud room. I don’t think it will be as great of a struggle, BUT last winter really brought to mind the question: how appropriate is a 100% cob house for the harsh north Missouri climate, anyway? I now believe that I probably wouldn’t do an all cob house again (in northeast Missorui, that is) — I think some straw bales, or bale cob, or even just a better insulated roof and floor would make all the difference. Again, in this climate, I think some insulation is necessary. Or at the very least, maybe some thicker walls. But this winter will be a truer test…

The living roof and skylight

The skylight is in fine shape. The foam seal has broken down a bit in the sun, but it’s not been an issue. Last winter, we had what we thought were some leaks in the roof, but once spring came around, those mysterious wet spots vanished, even after a record-setting rainy spring. Perhaps there are no leaks after all…

The roof has a tendency to dry out after long bouts of heat without rain since the soil is pretty shallow, but plants perk up once it does rain. I haven’t really selected for certain plants to grow up there, so whatever was in the soil originally comes up each spring. I wonder how the roof ecology might change over time, but perhaps I’ll try to grow a certain type of grass up there if the same old plants come up year after year. Some are less than desirable (ragweed… bleh), and I do cull those from time to time. Because of the shallow depth of the soil and the angle of the roof, it’s not terribly great for growing edibles.

I’ve yet to figure out how to gutter the roof, which would be hugely beneficial, because rainwater sheets off the surface in heavy rainfalls (of which we have many during the spring… and summer).

I do love the option of being able to climb up onto the roof and even watching shooting stars at night…


The foundation

Again, is clay/sand mortar really a good idea in this climate? It’s actually held up extremely well, but when it gets wet, it’s a problem. Last winter, when it snowed (and snowed and snowed), the foundation was in contact with that snow for a long stretch of time, and that’s what caused the mortar to wick moisture to the interior of the house. I think. This is my theory. In spring, we had earthworms tunneling through the mortar of the foundation! Ack! Portions of the floor around the wall were wet, too. That was not fun.

Will the same thing happen this winter? We’ve done some earth work around the foundation to keep water away, so perhaps we won’t experience the same thing. Here’s hoping.

In the end… after one year of life in a cob house

I love life in my cob house. It’s been a huge pleasure. Sitting in the rocking chair in the beautiful silence of the house, entering on a blazing hot day and feeling the cool of the floor on my bare feet, laying in bed and staring at the spiral of the roof, watching lightning storms through the giant south window, lighting candles and admiring the glow of the flame in the niches of the wall… these are a few of the moments that make living in this house so special.

Sure, there have been very difficult times, too, times when a certain problem caused so much stress (the failed rocket stove, or condensation) that I thought things were doomed, but it’s easy to get caught up in the moment. There has been much creative problem solving thus far, and life in Gobcobatron is a constant learning experience. I imagine that learning will continue for a long time. I’ve noted above several of the things I would do differently, were I to do it again. But there are many things I wouldn’t change, either.

So what is in store for the future of Gobcobatron? There are still a few projects to wrap up this year: finishing the stove installation and getting a second skylight pane are the big ones. But beyond that, there are musings of switching out the south window for an insulated one, and possibly even attaching a tiny greenhouse to the south. (It’s a wise idea to have two home heat sources, especially one that is passive.) Time will tell what happens and what new ideas we have for the house, though.

Now for year two of living in mud…

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  • Jenny

    Hi! I just wanted to drop a quick introductory line. My husband and I, along without our young son, will be visiting DR in the spring with an eye towards hopefully moving there not long after, and finding this blog has been sort of a lifesaver! I have been equally intrigued and intimidated by the idea of ‘building my own home’, not knowing at all what the process would be, nor what kind of finished product I could hope to look forward too. Your home is beautiful! Thanks to you for taking the time to blog about your experience. It’s made a world of difference to me, and has really eased some of my concerns. Hope we will have a chance to meet in the spring!
    PS – just out of curiosity, how to you do the solar panels? Do you purchase them made or do you buy the parts and assemble them yourself? feel free to email me if you want – whiskygo.go at

  • Karen

    I love the Gobcobatron, too, b/c of this wonderful blog! I would love to live in it for a year — post Morso, with second skylight pane and (my vote) a greenhouse on the south side. I’m looking forward to hearing about all further adventures in year two of occupancy and learning how the roof vegetation evolves over another season. Thank you!

  • McKenzie

    Thank you so much for posting this. It’s hugely inspirational knowing that other young people are making their dreams a reality! We’d like to build a strawbale home and nearly bought land to do it early this year. There are so many practical things to think about before diving right in though, so thanks for kind of “testing the waters.” Your home is beautiful. 🙂

  • John C

    About the towels to collect the condensation at the window – in Norway & Denmark they have two sets of windows, one on the outside of the wall & one on the inside, and they put not only their potted plants there inbetween, which do better, but they fill the sill inbetween with moss, which absorbs the condensation beautifully and stays very green and other worldly looking! Maybe try some moss there!!!! I love your endeavor, by the way. Next time make your walls thicker for more insulation, and maybe a storey and a half for warm wooden second floors.

  • Noah

    Just bought the Yes! Issue. Almost forgot! Hope all is well. Noah

  • Tom Meyers

    Rising damp. That is a phenomenom that involves water movement from the soil into walls. It is usually apparent in masonry where a white line will develop with white powdery efflorescence visible on the face.

    Not sure how cob reacts to this form of leaching. In any case, this is likely the biggest cause of your interior moisture problems. That and the fact that your floor is likely installed with direct contact with the ground. Both will allow moisture to wick up and into the interior by capillary action. Your “urbanite” concrete wall base is also notorious for this propensity.

    In retrospect, a damp course in the wall and some form of moisture barrier on the ground prior to installing the floor may have made a world of difference. Historically, masonry wall damp courses were slate or other impervious stone. Floors are a lot more difficult to damp seal without using some modern material such as sheet or insulating foam plastic. Sometimes we have to make some concessions to form a sustainable, yet livable environment.

    I had a discussion with David Eisenberg of DCAT about the mix of sustainable, natural and modern materials. He stated that he believes it perfectly acceptable to use modern materials in moderation when there is no better natural substitute. I have a feeling that one inch of R5 foam board under the floor would have made a remarkable difference in moisture and heat retention in your house. Small trade for the otherwise considerable effort you have made to promulgate sustainable alternative construction methods!

  • Josh

    This may not be the appropriate place for this, but your link to snail cabin on the side bar is dead.

  • Flik

    I’m incredibly impressed -thanks for the post

  • Josh

    Also, I just now realized that that first photo looks like a time lapse, based on the stars. You’ve got me curious…

  • Mark Angelini

    Wow, I’ve really enjoyed and appreciated reading about your successes and challenges. Keep up the great work!

  • bek

    we are in southern IL not too far from you, and have just “broke ground” on our year of mud…thank you for your help in this blog and your afterthoughts one year out have been particularly helpful!

    here’s to loving cob!

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  • Thanks for your report. It helps us know what we’re in for, and to know some things to avoid or to implement as we will be building something like this, but much bigger, for a family of 6. Wish us luck.

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