Give me a counter-case for strawbales so that I can be aware of all the negatives, please.

Hi everyone. Been reading permies for a while. Love this place. This is my first post here.

For background, I'm planning out an earthship build using strawbale walls as the southern face of the structure.  Structurally it is post-and-beam timber frame on stone piling foundation.  Clay floor over gravel over insulative foamglass gravel.

Downsides I know of:

1) Financing is not a concern, I'll be self funding

2) Selling is not a concern, this house is meant to stay in the family indefinitely.

3) Labor is...gonna suck. NGL. Seems no worse than cob or insulated roundwood or something. Of the natural building methods it seems about on par. I'm happy to spend more labor to have a natural materials home.

4) Connecting the earthen parts of the building to the strawbales seems difficult as the strawbales can't be in contact with anything earthen where it might conduct moisture

5) Strawbales might not be compatable with the earthship front greenhouse. Could be too humid?

What sucks about strawbales that I **dont** know about? Dump all the negativity possible. Try to talk me out of it.

I think the greatest downside of strawbale is that it's some form of a cavity wall that at some point will host bugs and rodents which is unacceptable to me. If there is a place for pest to live in, they will find it, no matter what preventive steps are taken. Nature is powerful and merciless.

https://permies.com/t/113626/Straw-Bale-Don

Strawbales were originally used in western Nebraska, which is drier and sunnier than the rest of East and Midwest and i think it's best fit for such climate.

Where are you located?

What does this mean please? "NGL."
Labour is always an issue with earthships.
I think the use of a 'joiner' panel or system between earth and strawbale would work, where a timber plank attaches to earth and the straw attaches on the other side.
Even some fired bricks in the joiner area would work.

John C Daley wrote:What does this mean please? "NGL."
Labour is always an issue with earthships.
I think the use of a 'joiner' panel or system between earth and strawbale would work, where a timber plank attaches to earth and the straw attaches on the other side.
Even some fired bricks in the joiner area would work.

NGL is new-fangled slang for "not going to lie".  Basically a short form of "i admit that..."

Thank you for buttressing my own thoughts about the feasibility of a merger of straw, wood, bricks, and earth in different walls.

It seems to me that different walls have very different needs and thus should not be built the same.  I want to use strawbales for my outer walls where insulation matters, and perhaps one or two inner walls where sound isolation matters.

But other than that it's better to have thinner walls with a higher thermal mass, and I think building roundwood walls (or just whole vertical 6inch trees cut to fit the wall space and then covered with cobb!) would be both thinner, quicker to build, and give desirable thermal mass, as compared to the bales.  

Then you go over to the retaining walls on the back berm of an earthship and you have a third set of wall requirements, including the ability to handle some potential moisture, to consider.

Yeah, I considered straw bales as a neat project for a storage shed.  When I looked at all the labor and framing I was going to invest for something that, for me, was of questionable duration, I decided for metal.  Now, for a storage shed, the insulation value of the bales was virtually pointless. Though it would have provided me with experience.

For thermal mass, adobe or mudbricks as we call the in Australia are very good.
I build a press that makes 8 inch x 12 inch x 4 inch bricks that are easy to handle.
You can puddle them with wood or steel forms as well.

John C Daley wrote:For thermal mass, adobe or mudbricks as we call the in Australia are very good.
I build a press that makes 8 inch x 12 inch x 4 inch bricks that are easy to handle.
You can puddle them with wood or steel forms as well.

I agree adobe or mudbrick are best for thermal mass, but a freestanding adobe/mudbrick wall between rooms would be significantly thicker and take significantly longer to make than roundwood, right?

And then for the retaining wall at the rear...I need a wall material to replace the tires as I want to experiment with an alternative to tires. But I don't think adobe or cob or rammed earth are suitable for applications that might get wet, and the rear berm will get r

Below is a short list of stuff that turns me away from strawbale, in no particular order.

When I say "expensive" I mean not just in terms of money but also in terms of time and/or headache, the environment, etc. as applicable:

1. The labor (as you said). Labor always seems to me like one of those things that is consistently a lot more expensive than expected.

2. I worry about rot in strawbale, especially if it's built by someone without a lot of experience doing exactly the kind of construction called for (in your case, both Earthships & strawbale).

3. Straw bale makes sense in certain places, less sense in others. Which kind of place are you in? Depending on your location, it might be a lot less expensive to use a different material that is more readily available locally.

4. Strawbale walls are a significant gobbler of square footage unless the house's footprint is expanded accordingly; expanding the footprint will make the foundation (and most everything else) more expensive, especially it's made with expensive ingredients.

And then for the retaining wall at the rear...I need a wall material to replace the tires as I want to experiment with an alternative to tires. But I don't think adobe or cob or rammed earth are suitable for applications that might get wet

Maybe it would help to look at the berm as a compromise?

If you install everything that needs to be there and do it absolutely right, then you get thermal mass without water intrusion, possibly even without humidity or mold problems, and your thermal mass helps regulate the temperature so you don't have to use a lot of energy to heat the house.

But in exchange you probably can't afford to be too experimental or picky with the retaining wall. I don't like the tires either, personally; I think I remember seeing that earthbags are a popular alternative but they usually end up being filled in with a lot of concrete in the end anyway (in fact, tires do too). So I would probably build mine out of concrete block or something a bit more "proven".

This all kind of leads up to the question, why are you berming at all? Might it be simpler not to, and find some other way to get a bunch of thermal mass? You could also do all four walls strawbale that way and avoid the joint issue.

Daniel Andy wrote:I agree adobe or mudbrick are best for thermal mass, but a freestanding adobe/mudbrick wall between rooms would be significantly thicker and take significantly longer to make than roundwood, right?

For adobe/CEB  it's recommended for the height to not exceed the 10 times wall thickness, so for 300 mm/12" block you could build 3 m tall wall.
Do you mean cordwood wall or just using round logs to make a rough looking wall?
In general I would recommend to not mix many building systems and reduce them to two main materials. It reduces number of tools needed and number of future problems of incompatibility and imperfect workmanship.
It would help if you shared with us some info about your location, terrain, soil type, etc.

Firstly, you are building an earthship, space should not be an issue.
When you think about we are talking about 4 or 6 inches across the building, its negligable!
As Christabel mentions, we need more information about the land, the climate location to give opinions about the rear wall.

John C Daley wrote: you are building an earthship, space should not be an issue.
When you think about we are talking about 4 or 6 inches across the building, its negligable!

Straw bale walls are what, 18” thick? 24”? Maybe more if you want them higher. That’s thicker than a conventional wall by at least 12.5”. There are a few ways to find out approximately how much square footage that eats up, but as a rough estimate you multiply the strawbale wall perimeter in linear feet times the thickness of the wall. If your equator-facing wall is 30 feet wide and sticks out 10 feet from the berm, that’s 50 linear feet. 50 x 12.5 is 625, so you’d lose approximately a Tiny House worth of space, or need to expand your footprint by that amount to keep it. (That’s if that wall is only like 8 feet tall, but I’ll bet you want it taller; strawbale has to be 5 and a half feet tall for every foot thick, according to what I’ve read.)

You might consider some hybrid, like proven hemp crete.     or dust crete ( sawdust )   instead.    

Much depends on where you are building.    I considered insulating my shipping container with straw bales, but the humidity here is florida  is such that that would be a very bad idea.

Other options like using styro crete with chopped styrofoam may be an option with high R values, but, that may not be a direction you would want to go...

Each choice you make has pros and cons for cost and R value, and longevity.

The one strawbale house I helped build, and then lived nearby for years afterwards, was almost lost to fire one night.  A woodstove located in one corner heated the straw behind a layer of stucco enough to start smoldering.  When the people realized what was going on, they broke through the stucco from the outside to get at the fire, which let in more air, and for a long time made the fire worse as they dragged out flakes of straw with garden tools and doused them with water.  Eventually they got it out.  But the whole corner behind the stove had to be replaced with cement blocks.  More attention to clearance and heat shields was obviously necessary.  Stucco of any thickness may be fireproof itself, but still conducts heat to whatever is behind it.

Thanks everyone for the thoughts. I see a lot of the requests for location but honestly i dont have one yet. Western north america but that doesnt narrow it down very much. I will happily share that once i have a location to tell you about.

The concrete and styrocrete suggestions are well taken but if i wanted non natural building materials then i ought to just use the standard tires as they are tried and true for the application.

I dont think a standing log wall with clay cover will increase my tool or repair complexity because its a combination of other parts of the house (timber frame and the clay cover on the strawbales.

This is advice I try to give myself, and try to remember to take:

The more you learn about construction, the less you will attach to any one particular method or material, and the more you will allow the location and the process and context to inform the decisions. These don't wrestle the decisions away from the guiding principles or sensibilities entirely, but all of them must communicate.

Keep learning and experimenting, and keep an open mind!

If you can, visit different kinds of "natural built" homes or structures, and pay attention to details there. What problems does it look like the builders had, and how did they overcome them? How do they solve or prevent the sorts of problems found in conventionally-constructed buildings? What lessons from conventional construction translate well to natural buildings? What do natural builders have to do that is completely different? Are there hidden costs about the natural buildings that videos or articles don't show? Etc.

Ned Harr wrote:

John C Daley wrote: you are building an earthship, space should not be an issue.
When you think about we are talking about 4 or 6 inches across the building, its negligable!

Straw bale walls are what, 18” thick? 24”? Maybe more if you want them higher. That’s thicker than a conventional wall by at least 12.5”. There are a few ways to find out approximately how much square footage that eats up, but as a rough estimate you multiply the strawbale wall perimeter in linear feet times the thickness of the wall. If your equator-facing wall is 30 feet wide and sticks out 10 feet from the berm, that’s 50 linear feet. 50 x 12.5 is 625, so you’d lose approximately a Tiny House worth of space, or need to expand your footprint by that amount to keep it. (That’s if that wall is only like 8 feet tall, but I’ll bet you want it taller; strawbale has to be 5 and a half feet tall for every foot thick, according to what I’ve read.)

That math doesn't work out, you're multiplying feet by inches. 50*12.5/12=52 sq ft. Not nothing, but definitely not a whole tiny house.

Nick Williams wrote:That math doesn't work out, you're multiplying feet by inches. 50*12.5/12=52 sq ft. Not nothing, but definitely not a whole tiny house.

Oops, you are correct. Good catch!