• Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Strawbale Earthship

 
Tom OHern
Posts: 236
Location: Seattle, WA
12
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
A lot of people get put off from the Earthship concept because of the used tires issue. A little known fact is that you don't need to use used tires for it to be an Earthship:

An Earthship is defined by the following 6 principles:

- Thermal/Solar Heating & Cooling
- Solar & Wind Electricity
- Contained Sewage Treatment
- Built with Natural & Recycled Materials
- Water Harvesting
- Food Production

I've started designing a strawbale earthship that I hope t o build in the next few years. It is a work in progress, but the basic design it done. Any feed back or thoughts would be appreciated!

Attached are some pictures of the design and the Sketch-Up model can be downloaded here.
Strawbale Earthship1.jpg
[Thumbnail for Strawbale Earthship1.jpg]
Strawbale Earthship2.jpg
[Thumbnail for Strawbale Earthship2.jpg]
Strawbale Earthship3.jpg
[Thumbnail for Strawbale Earthship3.jpg]
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Great design Tom, but as a builder, I have a few questions regarding simplicity of the build.
The Mansard roof on the rear and the jettied second floor are going to increase difficulty and cost, are they really worth it?
I think it might be better for the green house to have a pony wall and steeper glazing angle instead of 2 glazing surfaces.
Add a small eyebrow roof for the clerestory for summer shading.
Just my 2 cents
 
Tom OHern
Posts: 236
Location: Seattle, WA
12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks for the feedback Bill!

I realized as soon as you said it I let my self get too constrained by some initial parameters I had started out with, that I didn't realize I was making so much more work for my self. I've simplified the design significantly. I got rid if the backside roof and the jettied second floor. In doing so, it actually fixed a few other issues I had been struggling with in both of the bathrooms. I got rid of the multi-slope roof in the front in favor of a single slope roof with a vertical front to the greenhouse. It still has two glazing surfaces, but I think this design will be much easier to construct (and prevent water infiltration). Also, I have added in the rocket mass heater, and closets to both the bedrooms to be code compliant.

New Sketch-up file since it wouldn't let me update the old one.
Front - Strawbale Earthship v1.1.jpg
[Thumbnail for Front - Strawbale Earthship v1.1.jpg]
Rear - Strawbale Earthship v1.1.jpg
[Thumbnail for Rear - Strawbale Earthship v1.1.jpg]
Interior Strawbale Earthship v1.1.jpg
[Thumbnail for Interior Strawbale Earthship v1.1.jpg]
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
That looks great Tom, but I think you may want to reduce the amount of glazing on the house by eliminating a couple of doors and on the greenhouse by utilizing straw bales for 1/2 the wall. The problem with excessive glazing is overheating in summer during the day and excessive cooling in winter during the night. The very best windows, you know the kind regular people can't afford, are R-9 and an energy star rated window for your area is R-2. I would recommend finding old wood windows and doors that are commonly removed and replaced. I pick them up for free at my local window shop. These are R-1, but when combined with a large air space as can be created with an interior storm window, R-9 is possible.
Good luck, it looks like a great project.
 
Jay C. White Cloud
Posts: 2413
46
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hello Tom,

I like the general concept of earth ship architecture and many are pushing the 25 year mark (not very long however as architecture goes) and few are "weathering well." Whenever a design relies on "proofing" of any kind to stay dry...there are eventually issues.

One of the ways to look at this is to consider the oldest architecture in the world, be it stone, earth, timber, or a combination there of. On these, what needs servicing and/or replacement? It is usually the Roof...which is...a "proofing zone." Since traditional roofs are designed for servicing and/or replacement this is not an issue. In many systems that use stone as the "proofing mechanism" these incremental servicing-replacement periods are well over 100 to 200 years apart. Even fossorial architecture (i.e. earth ships of old) that employs stone for their upper cladding systems are even more enduring often exceeding 1000 years.

Now that brings us up to current trends in fossorial architecture...we just are not really thinking through the viable life spans of these cladding systems, many of which have only been developed in the last 50 years. These all have limited serviceable "life spans," and require replacement and/or extensive invasive servicing. Add to this an insulative medium that is prone to moisture degradation and you are designing a system that is bound to have major issues in lest than 35 years of service life.

I am not suggesting not building a fossorial type of structure. I am suggesting strongly understanding what "will" go wrong (not if) and how you plan on servicing that both fiscally and mechanically. Knowing this now will give you the chance to consider alternative systems. I also agree with:

Reducing the glazing.

Installing at least a meter high grade wall (pony wall).

Extensive drainage systems and podii style foundation system whether below grade or above.

I would further suggest no major or primary glazing on the living space itself but instead a separate attached green house solarium that can be isolated from the rest of the architecture when need be.
 
Tom OHern
Posts: 236
Location: Seattle, WA
12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks Jay,

I agree that the older earthship designs had issues that lead to longevity issues, but I think the newer designs have corrected a lot of those issues, and they should be much sturdier structures. I think in any event, they are probably as well build, if not better built than traditional stick built houses. I think a well ventilated strawbale houses with a metal roof, as I am planning on using, are going to be about as long lived as one could possibly get without building out of stone. If I am understanding what you are saying, it sounds like you think strawbale houses have more moisture degradation issues than other houses. That is not the impression I have got, and I don't see anyone making that out to be a major issue. Can you point to any particular issue with moisture being a problem in strawbale houses more than it is in stick built houses?

I am not sure why I would want to reduce the amount of glazing. Bill suggested reducing the glazing surfaces to just one, but not necessarily the amount of glazing. In tandem with your final suggestion, it sounds like you think having the attached greenhouse is problematic... Since the attached greenhouse is kind of fundamental to this design, separating it would seem to destroy most of its functionality. Is there a reason you think this should be done?

The podii foundation info looks interesting and I will look more into that.
 
Jay C. White Cloud
Posts: 2413
46
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Tom,

I apologize if it sound like I am trying to dissuade you from you current plans...I am more concerned with details and modalities than overall concepts, and this only comes for decades of experience. I love, in the correct environment, with appropriate design, and approach methods fossorial architecture. It has been with us for millenia, and more than proven its worth. Unfortunately I see few (not all or them mind you) than actually will have a viable life span of more than 30 years without major intervention...and more abandoned each year for a "redo" and/or complete rejection for a surface dwelling. Some of the "Wofati" style structures show great promise, as these follow a traditional matrix more than most, and Walipini or "Bikooh Garden" logic is also very applicable in the correct environment.


... I think the newer designs have corrected a lot of those issues, and they should be much sturdier structures...


Hmmmm....this is probably both subjective and academic on both our parts, and I don't find it to be the case. Most are too "young" to really know how they are going to fare over time, and the ones that do work are being built with more traditional methods and/or following the "Wofati" outline. We will only know as time goes one what is really going to work well with the "reinvented versions" of a ancient method...and now it would seem...to be the one that stray little from proven forms. This is kind of my point...I see so many trying to "reinvent wheels" when proven traditional systems are already viable, have and do work, why take a chance (unless you are a building scientist with a budget to conduct these living experiments) with the only home you have.

...I think in any event, they are probably as well build, if not better built than traditional stick built houses...


I compare nothing to "stick built" architecture, as I find it one the lesser forms of architecture since its inception around 1850. It was and is "transient" in nature, and developed out of the need to "build the west fast and with unskilled builders," as well as support "industrial revolutionary" concepts of architecture and profit.

I think a well ventilated straw bale houses with a metal roof, as I am planning on using, are going to be about as long lived as one could possibly get without building out of stone. If I am understanding what you are saying, it sounds like you think strawbale houses have more moisture degradation issues than other houses.


I love SB, and have even facilitated a few over the years, as well as consulted on many. Great form of architecture if the bales do not have to be shipped 100 or 1000 of miles. The new (actually very old) concept of "straw clay" or "insulative cob" is probably a better form of it. My only concern and one that I would only facilitate with great caution and a layered design modality would be SB below grade as you are suggesting.

I am not sure why I would want to reduce the amount of glazing. Bill suggested reducing the glazing surfaces to just one, but not necessarily the amount of glazing. In tandem with your final suggestion, it sounds like you think having the attached greenhouse is problematic... Since the attached greenhouse is kind of fundamental to this design, separating it would seem to destroy most of its functionality. Is there a reason you think this should be done?


Yes, I do believe, again from experience and feedback from many that have them, that attaching green house walls to structures can be very problematic in numerous ways from overheating, becoming to cool at night and during winters, leaking, etc. Making them a self contain separate structure removes issues with heat and cold, while still giving the benefit of having a "weather lock" space between them and the primary living space. Some of the better built Wofati style fossorial architecture with attached Walipini or "Bikooh Gardens" work much better, in my opinion and shared observations, than any of the "earth ships" I have seen.

Whatever the outcome, we all look forward to following along on your building adventure.

Regards,

j
 
Brian Knight
Posts: 554
Location: Asheville NC
8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
J & B have some good advice. I think we like your design overall but its in our nature to improve on what might otherwise be perfect. Youre wise to plan years in advance of actual construction.

Youre not thinking of backfilling strawbale walls below grade are you? I dont really have any problems with Earthship's use of tires for the indoor air quality concerns, as offgassing should be addressed with a proper fresh air system. Labor on the other hand.. My main problem with Earthships is with the attached greenhouse aspect. If you havent already, check out the many threads here on attached greenhouses. Iam curious what the main benefits of function you intend to get out of one. They tend to have wide fluctuations in temperature, high humidity and usually impact a home more negatively than what more typical passive solar design offers.

It looks like your upper windows will get too much shade in the cool seasons and the "panels?" might see too much shade in the warmer seasons. Those are small issues that would be easy to adjust the overhang for, compared to the overall performance problems you might have with the attached greenhouse and glazed wall separating the home from the greenhouse area.
 
Tom OHern
Posts: 236
Location: Seattle, WA
12
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thank Brian, the reason I posted here was becasue I wanted to get a variety of opinions. I may not always agree with them, but still I want to hear them!

Nope, no plans to berm up any of the walls. Here in the maritime PNW, our climate is mild enough that I am not convinced that any sort of buried walls/structures are really going to be an advantage. We don't get enough consecutive days of sunshine to really heat up any annualized solar thermal mass. This is the reason I'm not going with the traditional earthship rammed earth tires, and opting for strawbales instead and have a rocket mass heater for supplemental heating. Getting rid of the tires also gets rid of the labor issue. Strawbale houses are fast and easy to build in comparison!

Places where I have seen attached greenhouses have issues are places where you have high humidity/low dew point issues or where you have extremely hot summers and not enough ventilation. Neither of those factors are an issue for where I live. In fact, I have been to more than a few homes in the Puget Sound region with attached greenhouses that seem to do great and have heard nothing except praise for them from the owners. I've been reading this forum for a while and, while I've seen the occasional person object to them, I didn't really ever see why. I didn't find any particular in-depth discussion on this topic, but if you have a thread in mind (or specific keywords to guide my search) I'd love to read more. Even better, if there is a discussion of attached greenhouses in the PNW, that would be the best. I'll keep looking and see if I can find more.

But you were right on the roof shading. I thought I had been careful in calculating my overhangs to maximize exposure/shading at the right times of year, but looks like I was about 11 inches to long. That has now been fixed. Thanks.

And not related to my build since I am not using tires, with the idea off-gassing of tires in earthships that do use them, I think a lot of drama is made out of nothing. The research that gets pulled out to say there is an issue was done on shredded tires used in play areas. I have no doubt that freshly exposed rubber surfaces that are subjected to UV degradation, hot and cold extremes, as well as all the other weather elements, would start to offgas and leach. I think it is an entirely different issue when you take used whole tires and encase them in several inches of clay where they are not exposed to any degradating elements. The New Mexico Environmental department determined that there was no risk of off gassing or chemical leaching in such an environment, and I am inclined to accept that conclusion.
 
Jay C. White Cloud
Posts: 2413
46
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Tom, I am confused

If this is an "earthship," and you are using SB as a structural wall, then you are backfilling against the SB wall...otherwise this isn't an "earthship" but instead just another structural SB home?

If not, what did I miss?

How are you insulating the roof, SB again? Brian will follow right up behind me on this one, as SB architecture mus have an ability to permeate (breath) on both sides of the wall freely, with more than just "vented air."

If you have viable working attached greenhouses in your area, and no chief complaints from them, then you may have something unique to your region. As a professional designer and builder (like Brian) we tend to only choose a "system of building" after hundreds if not thousands of comparatives not just a few "possible" feedback loops in the "we like what we have," arena. Many folks with a particular system often will overlook the shortcomings because they really do not have an alternative to consider...they live there already. I would also ask how old these attached GH are? If any of these attached GH are over 40 years in age then that is a big positive to have one...otherwise I would continue my research.

I love meeting and working with clients, students and DIYers. I will share that way too many of them try to "reinvent wheels" without the background, experience or know how to fully understand an "integrated and disentangle architectural system." That is why folk like myself tend to suggest folks go with what "is known" to work, and has a track record of working...That being a track record of 100 year or more not just a few decades at best.

Either way we enjoy the conversation and you continueing to share you ideas. Please do keep us informed of how things go...no matter what you choose.

Regards,

j
 
Bill Bradbury
pollinator
Posts: 684
Location: Richmond, Utah
32
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Tom, I did actually recommend the pony wall and reduced glazing and I agree with Jay about SB being problematic when not detailed impeccably, especially in your mild, wet climate. I try not to broadcast my opinions, but if asked I would not recommend SB in your climate. SB makes a lot more sense here in the cold/hot, dry high desert of Utah, but i still would not utilize this method myself. There is a hi risk of failure if the house is not maintained. On the other hand, I have repaired adobe, stone, pise and even proper stick-built homes that were neglected for long periods of time. You don't sound like the kind of guy that would ever neglect a house, but what about 100 years from now?
I have experience with only one attached greenhouse. We had to install 3 fans(2 exhaust outside and 1 to the interior with speed control) on separate thermostats in order to gain control. It seems to work fine, but he uses an old parachute in the heat of summer to prevent over-heating. This is my climate though,-25F in winter and 100F in summer, so take that with a grain of salt.
 
Matthew Nistico
Posts: 269
Location: Clemson, SC ("new" Zone 8a)
14
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hello Tom,

Congratulations and best wishes on your project! Looks like you are putting a lot of time and thought into your design, including how it will perform and how it will actually be built and maintained, not just how you want it to look or how "cool" a particular material or method may seem. This is of course essential, yet seems inexplicably absent from the design process for so many owner/builders. I am a first-time straw bale owner/builder/designer myself, and have over the years met many others aspiring to projects like ours. Perhaps it has just been my bad luck to meet these people during the early, conceptual phase of their projects, but they almost never fail to impress me as being woefully uninformed and unprepared for what they are getting into. Most have seen a few pretty pictures in books and said "ooh, I want that!" Few have started with a methodical, introspective design process addressing the key questions: What are my design goals - practicality? economy? longevity? aesthetics? low energy consumption? resale value? What lifestyle do I plan for myself that this building will support, and why will one design or building material be better than another to do that job? Do I have a realistic and informed time frame/budget/pool of labor? Even fewer have even the tiniest inkling of the magnitude of research, planning, and hard work that will be required, or of the problems they will encounter along the way.

In any case, you are clearly not among that crowd. Again, congratulations. You clearly desire to produce a superior product ...and if the natural buildings we create are not actually superior to the industry-standard mainstream options already available to us, often for less cost and certainly for less effort, then I consider that a failure.

I will admit that I'm far better versed in straw bale architecture than I am in earthships, but I share Tom's stated surprise at your design. Or at least your nomenclature. I had actually caught on way further up in this thread, based on the look and placement of the ground level front door on your north side, that your design does not include earth berms. So I echo Tom's question: if it is not built into a hill, bermed up, or otherwise earth-integrated, why do you call this an "earthship" as opposed to simply a passive solar straw bale structure? I had thought that was part of the definition of earthships, at least in practice, if not according to your six principles.

Having myself also designed (and mostly built) a passive solar straw bale home with a metal roof and an RMH for supplemental heat, I am of course inclined to appreciate your design. (BTW, buy the metal direct from the factory and install the roof yourself - it is easy to pick up the proper technique if you have a drill with a clutch, and you will save so much money!) I also agree with your statement that a well-built straw bale structure should be no more inherently susceptible to moisture damage than a home built of wood. Wood rots when wet just as completely as straw; it only takes a bit longer. Of course, wall systems based on stone or masonry (or tires) don't share this problem. Bill is correct of course that straw bale must be "detailed impeccably" ...but shouldn't any owner-built structure be? It is only the mainstream construction industry that knowingly builds poor detailing into its product. And I don't even fault them for this; they are giving their customer exactly what he wants, which is low sticker price above all else, including longevity. I would have agreed with Tom that a straw bale wall has no business against an earth berm, no matter how well vented, but of course you are not planning to do so.

I must take issue with one thing you wrote, however, and that is "Getting rid of the tires also gets rid of the labor issue. Strawbale houses are fast and easy to build in comparison!" Oh, don't even be tempted to think so, good sir! And don't believe any of the books you have read that suggest as much. I read all of the same books, and they are false advertising. Straw bale walls are extremely labor intensive to raise and finish. Perhaps not as much so as monolithic cob, but make no mistake: the man-hours required to complete a straw bale structure will boggle your mind once you are actually into your project. I will concede that a VERY small, VERY simple, load-bearing design could be built reasonably quickly and economically, compared to the standard stick-built house. But this assumes 1) meticulous and flawless preparation of the site and materials and day-by-day schedule that will be used, and I'm talking about a quality of planning that no first-timer should ever expect to achieve; 2) a large and dependable force of free labor to aid in the initial bale raising, keeping in mind that "free" and "dependable" are often mutually contradictory terms; and 3) damned good luck.

In any case, from studying your schematics above, none of these apply to you. Your house is not very small (two bedrooms, a stair well, a separate kitchen, and a separate living space ...I am guestimating just over 1000 sq ft, plus the greenhouse?), it is not very simple (two stories, two roof lines, and an attached greenhouse), and I can only assume given your location that it is a non-load-bearing design. Modified post and beam? That is what I chose, and it is a good system (including good for selling your design to code officials), but it means a lot of extra work compared to load-bearing.

BTW, if you were to say that you actually do intend load-bearing straw bale, I would emphatically advise against. Builders in the desert or Great Plains attempting a well-organized blitz on a maximum 500 sq ft, one story, simple square floor plan can get away with load-bearing designs. They can reasonably expect to get from bare foundation to completed roof sheathing within one month, and are accustomed to longer stretches without rain. You have no such luxury in Washington, nor I in South Carolina. Even those desert builders would still take additional weeks to finish up the first coat of exterior plaster, until which their walls are still somewhat vulnerable, even beneath a roof.

If you would like to provide more details of your design and construction plan by PM, I would be willing to make further comment based on what I've learnt through hard experience. I'm sure many other permies would have good advice for you as well, if you posted in the straw bale forum rather than the earthship forum.

As for the attached greenhouse, I share Jay's concerns over the basic design, though I can claim no first-hand experience in this area. But one of my PDC instructors gave me the exact same warnings that Jay has given here, and she should know: she lives out west and she is old enough to have been around the first generation of earthship architects as they pioneered the concept, and to have observed the results 30 years later. She called those early attempts at passive solar design "solar brutal," claiming they only resulted in unusable living spaces that were too hot during the day and too cold at night. You live in a more moderate climate than those earthship pionneers (PNW vs SW), with milder winters and much less solar exposure in the summer. This is surely in your favor, but still I would crunch the numbers rather than rely on such anecdotal logic. And/or design in features to mitigate temperature extremes, such as exterior shutters/louvers for reducing exposure on sunny days, and heavy interior drapes for insulating against cold nights. If manually actuated, such features shouldn't be too expensive. Even better, so long as you prepare for them in your design, you could plan so that they would be left as a possibility for retrofit only if proven necessary by the first year's experience.

And/or you could detach the greenhouse from the dwelling structure as Jay suggested, or at least place an insulated wall in between the two. With ducting through this wall, you could set up a blower system to transfer heat from one area to the other as needed, but under your control.

Some things to consider.

Again, best wishes! And thanks for posting your excellent schematics.
 
C. Hunter
Posts: 111
4
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
what about moving the greenhouse 6' out from the house and building a (vented with transom windows, maybe?) roof between the two? Heck, make it 8' and you'd have a very nice patio-sized weather lock/semi-outdoor living space that would mitigate, I think, the humidity up against the house?
 
Tom OHern
Posts: 236
Location: Seattle, WA
12
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks all for the comments,

Matt, those 6 principles I posted in the first post were actually copied and pasted directly from the Earthship Biotecture site. They are not mine, but are actually what Michael Reynolds defines an earthship as. It is true that most earthsips have earthberms as a way to store solar energy, as per the first design principle, but there is no requirement for it. The point is to have a home that is as self sufficient as possible, and in my climate, there just is not enough days of sunshine to justify a earthberm wall. Instead I've opted to go with the superior insulation of strawbale.

In this design it is important that the greenhouse is attached because I will be circulating the warm air from the greenhouse into the main house. I could do this with insulated vents and such, but that significantly increases the complexity, and probably makes passive air circulation much less of a reality. This would be a problem if the air in the greenhouse was very moist and I pushed that air into the house. But, and maybe I just use greenhouses differently than other people, but in my current, stick-built detached passive solar greenhouse, I do not have moisture problems. I do plan on putting a vapor barrier up between where the greenhouse attaches to the strawbale wall which will prevent issues there.

For me though, the last 5 points are far more important than the Thermal/Solar Heating & Cooling, and those self contained systems are what differentiates any other home from and earthship. And yes, I was thinking I would go with post and beam rather than load bearing strawbale. I've heard both your view that load bearing is much harder and the opposing view, but in the earthquake prone PNW, I think post and beam is a much more resilient structure. Plus, I want to get the roof up ASAP so I don't have to worry about a surprise rain storm that soaks my bales as I'm putting them up.
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic