Straw bales to insluate the inside of a compressed earth block wall?

We are located in central Illinois, and want to build a family home with natural materials in an area that essentially has no building codes (my family has land in such a place).
The land has few trees, and indeed there are no forests in a 15-mile radius--it's prairie country, and we want to build a house reflecting that and using less wood, if possible. Because the climate gets very cold in the winter, straw bale tends to be the preferred natural building method in this region.

Has anyone heard of compressed earth block structures insulated with straw bales on the inside? Seems like it would require a very wide stem wall... but maybe not if the compressed earth blocks are laid lengthwise instead of widthwise?

I would consider load-bearing straw bale for a cabin, but it seems to have questionable long-term durability for a family home.

Aesthetically my wife and I are taking inspiration from the traditional Ukrainian mazanka, lime-plastered earthen buildings built in southern/eastern Ukraine, a place with a lot of similarity with northern/central Illinois in climate and terrain.

Hi Jonathan.

Welcome to Permies.

Cool idea, but I would flip it around. Put the mass on the interior where it can moderate the temperature of the living space.

I agree with Phil, use the insulative characteristics of the strawbale outside and the thermal mass qualities of the compressed earth bricks inside.
I have built machines and made many compressed earth bricks.
How do you propose to create them?

I would not mix two different building systems. Any interface between materials is a potential problem.
I would rather do 3 wythe wall: block - insulation - block. Also, I would never like to use straw in humid Illinois despite people thinking otherwise. Rain is the enemy of materials that deteriorate with water.

Cristobal Cristo wrote:I would not mix two different building systems. Any interface between materials is a potential problem.
I would rather do 3 wythe wall: block - insulation - block. Also, I would never like to use straw in humid Illinois despite people thinking otherwise. Rain is the enemy of materials that deteriorate with water.

I agree about mixing systems.

Could go with adobe or earthblock interior walls for thermal mass.

Many people build strawbale homes in wet climates, it is humidity in tropical climates that can cause problems. A good Natural Hydraulic Lime (NHL) plaster would work well.
I just did a strawbale home workshop in Michigan this past fall. with:
https://strawbale.com/

Great peeps and resources.

Kyle Hayward wrote:Many people build strawbale homes in wet climates, it is humidity in tropical climates that can cause problems. A good Natural Hydraulic Lime (NHL) plaster would work well.

It's possible, but not necessary the best choice. In California many people (like 99.9%) build houses from sticks and OSB board in the areas that are raged by wildfires. They burn nicely, I saw it. Then they rebuild - the same way.
In general I would not recommend a system that needs extensive plastering. It's a lot of work.
I'm plastering my house and we are only half way done and only in interior so far. I do it, because I like lime plaster finish and whitewash, but it's not necessary in my case, but for the straw it's a must.
Also, NHL is not something that is cheap or easily available. If anything I would go with regular high calcium lime plaster.

Cristobal Cristo wrote:

Kyle Hayward wrote:Many people build strawbale homes in wet climates, it is humidity in tropical climates that can cause problems. A good Natural Hydraulic Lime (NHL) plaster would work well.

It's possible, but not necessary the best choice. In California many people (like 99.9%) build houses from sticks and OSB board in the areas that are raged by wildfires. They burn nicely, I saw it. Then they rebuild - the same way.
In general I would not recommend a system that needs extensive plastering. It's a lot of work.
I'm plastering my house and we are only half way done and only in interior so far. I do it, because I like lime plaster finish and whitewash, but it's not necessary in my case, but for the straw it's a must.
Also, NHL is not something that is cheap or easily available. If anything I would go with regular high calcium lime plaster.

Not sure what the California home story is supposed to illustrate? Although strawbale home do very well in fires because the very thick plaster is resistant and compressed bales don't burn well, like a phone book won't burn well.

No doubt that plastering is work, but as you and I and I suspect most people that do it, find the finish very appealing. Also you can balance the cost of NHL or other lime with a natural earthen interior plaster.

Certainly everything has it's pros and cons, I was just offering an option/information to the OP.

Christobel

I would not mix two different building systems. Any interface between materials is a potential problem.

IMO potential problems can always be addressed, and I know of none in this suggested case.
Most houses will have a mixture of systems, and there is limited evidence of ongoing problems.
With regard to plastering,  hard work never hurt anybody who sets out knowing what the future will entail.
Just build a smaller house if the task is overwhelming or use a spray unit to apply the plaster material.

Of course systems are getting mixed, but I never saw strawbale/CEB wall and if someone is building the first/only house and asking questions I would simply not recommend it. On some shed yes, but not on the house.
Regarding plastering, it may just burn the new builder.  People on the homestead already have a lot of tasks to keep them busy.

What I would do is strawbale for the exterior walls and CEB for interior (partition) walls. That way you're not mixing systems and each gets to do what it's best at.

Jonathan,
I like the idea of mixing building systems but my concern stems from moisture migration. In Illinois winter wall temp will be well below freezing, making a condensing surface somewhere in that wall. If that happens to be the interior side of the block, will it rapidly degrade with the freeze / thaw of condensed moisture? Maybe you could create a small test area of your current residence to test? Here in Nebraska we still have straw bale houses standing after a century. Don't be afraid to use straw, you will not regret!

We have a straw bale home that mixes building systems, and after 20 years see no obvious moisture problems.  External rock, followed by vapor barrier, 2x4 framing, straw bales l, covered internally with gunnite (sprayed on) and final stucco finish.
No obvious way for air leaks (to bring moisture into the wall.  Super well insulated too.  

I can't imagine building anything with strawbales unless the bales were treated with clayslip/ borax.

That said, how about a light clay straw infill?
It would require some solid framework,probably out of wood, but not nesisarily "load bearing" wood.


If compressed earth block is none negotiable, I would build with  preparations for adding straw bales to the outside.
That would probabley mean either a really wide stem wall or floor joists that cantilever out past the stem wall.
The extra wide stem wall makes more sense in a context of wood being hard to come by.
Either way, the eves will need to be that much bigger.

I wonder if a meaningful amount of  insulating straw/cob mixture could be applied to a compressed earth block wall without risking delamination?

I imagine metal tie ins and lathe could make it possible,  but that would add time and expense.

CEB Inside and Strawbale outside has been done. For an example in Canada, see https://fifthwindfarm.blogspot.com/p/construction.html

Jonathan Carr wrote: taking inspiration from the traditional Ukrainian mazanka, lime-plastered earthen buildings built in southern/eastern Ukraine, a place with a lot of similarity with northern/central Illinois in climate and terrain.

not only lime, clay was used more often

Yaroslav, that is nice, of course we for get about the houses in Eastern Europe.
I guess there are plenty of clever designs aswell.