Round interiors

Hi everyone. As I'm quite new to the topic I would like to ask for your advice. My husband and I we are planning to build our earthbag home (which I've been studying for a while now). We love those round interiors in some of the houses we have found on the internet (we hate square and pointy, anything modern is a no for us). And here is my question: how to make them happen? How to build those beautiful round interiors? Do we need to use cob or other materials? I tried to find some info on the internet but as English is not my first language I can't really figure out the search phrase that would give me the results I want. We appreciate any help.

Maggie, Welcome to the forums!

Since the title is "round interiors" are you planning a square foundation/building with just round interiors.

Yes, I feel the interiors are Cob.

Here are some threads you might find interesting:

https://permies.com/t/138968/logs-trusses-green-roof-oval

https://permies.com/t/139433/Earthbag-shed-foundation-cheap

https://permies.com/t/141317/build-earthbag-home-close-city

I am sure some of our earthbag builders will chime in.

Hi Anne
Thank you for your answer. No, we are planning to build earthbag dome as we fell in love with round shapes. We also would like to know what to use and how to shape the interiors to be round (like those sleeping alcoves, shelves and the whole interiors in general).

You might watch the forums or your local area for Cob Workshops.

Here is our Cob Forum:

https://permies.com/f/76/cob

Here is some info on cob to get you started:

https://permies.com/wiki/8313/Hand-Sculpted-House-Ianto-Evans

https://permies.com/t/16233/Making-cob-basics-basics

https://permies.com/t/166230/Interior-walls

Those curves are readily made with Earthbag construction and they are probally easier to do with earthbags.
Here is a video on the subject
If you search "earth bag construction" you will see a range of books, all of which I have and they are all ok.
The reason I say earthbags may be better is that from experience cob is harder to work with when inexperienced, earthbags have
an ability to hold together as you bring the walls in ti create a curved ceiling.
If you can purchase the long sausage bags in Poland, it will be a lot easier.

John, thank you for your answer and video. It's a great video showing the process of building. I'm afraid it will be hard to find those bags in rolls in Poland. I tried to research it but all we seems to have is a single bags in different sizes. Non in rolls in UK either.
The shape of the dome itself will give us nice curves of the building but I would like to know how to do the interiors similar to the pictures I have attached to this post (benches, alcoves, shelves etc). Should I use earthbags as a base and then cob over it and use some limewash at the end?

Also one more question popped into my head after watching your video John. Roof. As in Poland we have proper 4 seasons which means hot summer, cold snowy winter and fair amount of rain during spring and autumn, there is a question of waterproofing the building. As I read on Owen Geiger's blog waterproofing domes is always tricky as we want our walls to breathe. I was thinking that maybe I should keep the round structure but instead of complete dome make a round roof like on the video you posted for me. I can see them filling up the roof area with some sort of material and I'm guessing it is done to insulate it. What can provide me with the best insulation in this type of roof?

I will answer the question about forming the curves a bit later.
In Melbourne, Australia we have similar weather, so I am familiar with it, its nice.
Most of the buildings you desire are built in dry areas, but I will find something for you after a bit of research.
Essentially the shape waterproofs it, but regular rain can cause issues.
the-best-introduction-to-cob-house-and-cob-building/



A collection of photos of cob homes
You will see they all have a flattish roof. And not a lot of 3 D curves.

Images of earthbag building

You can see the curves coming into the designs, earth bags lend themselves to this shape because they are a lot drier when being laid. Thus they do not collapse as easily.

As for the bags, you dont need to get "earthbags" I am sure there will be manufacturers of woven bags for chaff and other things that you can get. Sometimes the printing on the bags is incorrect and of no use to the chaff people, but ideal for earthbag construction.

Side issue - info for Aussie building, even in colder areas, may not be appropriate for central Europe! Poland gets a LOT colder than Melbourne, so would need more insulation. In Australia even the coldest areas tend to just have cold nights but the days are always above freezing. I was shocked my first properly cold winter in the UK to have an entire week where the temperature never got above freezing and the ground froze solid! And Poland is colder than the UK.

Maggie, I don't know a lot about earthbag building, but I've seen videos where people use the sort of empty sack used to make sandbags for flood protection. After filling them with earth from your site, you'll need to sew them closed flat at the open end with wire and a large needle. Here's a place in the UK that sells them: https://uksandbags.co.uk/Shop?category=Empty%20Sandbags If you're building in Poland, they would most likely be cheaper there. The only issue I see using those bags is that they do deteriorate with UV light - but as they'll be plastered over, they should be fine.

You'll most likely find a mix of cob and earthbag works for building your interiors - earthbags to rough out the shapes and cob for the detailing. That beautiful bed set into a deep niche - could be that's built as a mini-dome? It's also possible that's an interior in a house carved from the rock. I've seen similar in underground homes in opal mining areas in outback Australia.

Jane thanks for the weather conditions update, I will defer to your knowledge.
Melbourne does not get snow etc, I guess I was thinking in terms of the changeability in a day concept.

It should be noted taht you will see it written that cob and earthbag has no insulating properties.
That is because the tests for insulation values are based on fibre insulation.
Cob, earth etc works differently, but insulation can be applied if you want it, but is harder.

Melbourne is definitely changeable. Four seasons in one day. Gotta love the place! Just - winter is a little more extreme on the continent.

The insulation value thing is interesting, and I think actual liveability and R values can turn out to be two different things. Earthen buildings usually have very thick walls and a lot of mass. What I see if that they are good for winter homes that are lived in and heated and built with passive solar heat gain in mind, but take a long time to get warm if left empty or if poorly aspected.

I'm in the process of buying a mudbrick house in Bulgaria, and am pondering adding extra straw-clay for insulation. They tradiionally used it in ceilings and floors, I wonder if a few inches  added on the interior walls would be good, or if it would interfere with some self-regulating process in the wall.

Don't want to hijack Maggie's thread, but John, I would like to ask you about metal roofing and rainwater harvesting for my house in a different thread at some stage as you clearly have excellent expertise. Neither are much used in Bulgaria, but with rainfall patterns changing and aquifers drying, I can see there's going to be a need.

Jane, you're more than welcome to hijack a bit of my thread because I can learn from that too . John, Jane is right. Our winters can get pretty cold, if we're "lucky" it can get to -10 Celsius and if we're "very lucky" it can even go as low as -20 Celsius. I know we will need a lot of insulation for this type of winter.
I was again reading on Owen Geiger's blog, that there is all sort of insulation materials to put in the bags in colder climates. He says: "Earthbag building has the unique advantage of providing either thermal mass or insulation, and therefore can be adapted for cold climates with an insulated fill material. Scoria, pumice, perlite, vermiculite or rice hulls could all be used for insulation". Most of those materials unfortunately is a mission impossible to get in Poland but thank God we do have perlite .
I was thinking as per Owen's advice to fill the bags with 50% perlite and 50% with earth and other recommended ingredients.
All I'm fighting with now, is a round roof... sadly my country is soooo backwards... Anything that is not square just doesn't exist, so finding simple materials to connect the wood together to build such roof will be another mission. Maybe I can get them in the UK before we go to build in Poland.

Perlite sounds a good thing to use - I was also considering this where insulation is needed as it's so readily available and I think more insulating than straw.

Hmm, not sure where you would find the fittings for a round roof. Once you've worked out the size of your house and know what size rafters you'll need and how many, you might need to talk to a metal fabricator and get something made for you. In my experience many Polish people are practical and resourceful, so you should be able to find someone to do that. That or get clever with metal strapping to connect it all together. If you'd have access to round poles where you're building, would a reciprocal roof work for you? They're used on a lot of round houses. Usually with a pole-framed supporting structure and infill walls, but I can't think of a reason they wouldn't work with a load-bearing earth bag wall.

The challenge would be dealing with the lateral forces of the roof trying to push the bags outward, and finding a good way to secure the roof to the wall. But earthbag builders would have worked out ways to deal with that, because pretty much any type of roof attached to a loadbearing wall has the same issue. Adding extra timber bracing between the rafters, or wood lining the ceiling under or on top of the rafters as they did in the video John shared, is a way to strengthen the roof to manage those forces better.

Don't limit your searches to just "cob" and "earthbag". Biomorphic Interiors" might help you in our search.

Robert, wow, that just opened a whole new level of research for me. Thank you for the tip!
Jane I have spoken to my Polish friend as he is an expert in building all sorts of roofs and he spent some good time working on different projects in USA and he said that there is no problem making those. Exactly as you said I can have them done by metal fabricator exactly how I want it. But scrolling through some videos I have came across something that could be a live saver in terms of doing the concrete bond beam to secure the roof. Here is the video:
https://www.youtube.com/watch?v=kvptRST4qTM&t=284s
They didn't use any of those metal fittings and also didn't need the concrete bond beam  (which I'm dreading to be fair). They have made those wooden elements (I won't even attempt to guess their English name ) to hold the rafters, secured them with nails to the earthbags and then tamped some more bags to secure the entire structure. Brilliant! And with overhangs from the roof my nightmares about keeping the building from leaking would be at least partially sorted.

That's an awesome video, Maggie! What a great job they've done there! Looks like as well as nailing the rafter holders to the earth bags beneath (LOL, no idea what the correct technical term for those wooden devices is!) and tamping bags over them, they used extra pinning down through the bags to keep it all in place.

I think the concrete bond beam is something that may be needed in hurricane or tornado zones, but what they've built looks plenty solid enough.

Looks like with earthbag, it's very like cob in the overhang width and amount of advance planning that's needed. Down to where you want cabinets and electric fittings, so the wooden pieces to attach these things to can be incorporated into the wall as it's built.

It's all going to come together for you guys! A lot of hard work, and you'll have a beautiful home.

Jane,

(LOL, no idea what the correct technical term for those wooden devices is!)

Thingmajigs.

Robert, where on earth did you find this  word?

 Biomorphic Interiors"

"Biomorphic design is a design where forms and masses have organic abstract forms. that seem to be mobile, vibrant and far from geometric fixed forms. Biomorphic or organic. forms are linked to the natural processes which allow the designer to explore the natural. world, without being directly represented."

John C Daley wrote:Jane,

(LOL, no idea what the correct technical term for those wooden devices is!)

Thingmajigs.

Robert, where on earth did you find this  word?

 Biomorphic Interiors"

"Biomorphic design is a design where forms and masses have organic abstract forms. that seem to be mobile, vibrant and far from geometric fixed forms. Biomorphic or organic. forms are linked to the natural processes which allow the designer to explore the natural. world, without being directly represented."

I was first hit with that word in a sculpture class many years ago.

Hi, this is Rose.  We are currently building our earthbag home in Northern AZ.  After all the research and questions and more research, we decided on the 50/50 mix of our dirt/clay and volcanic cinders that are available in our area.  We are using Lime cement as a hardener.  Like you, we love the round shapes and all of our home will be domes.  A final total of 8.  We will be using cob, plaster and smaller individual sized sandbags to do most of the built ins.  The bags are so easy to mold into the correct shape and then cob over them.  It works very well and I have been experimenting with the different plasters and techniques to figure out what will work best.  I will share pictures as we start getting further along in the process.   Welcome to Permies

You can do those interiors in various ways. But there are two components to the task. 1) Provide tensile strength. 2) Support while the structure is curing.

For (1) you could either fill the sacks with a dirt-cement mix that will harden to provide structural strength. The other would be to use bricks/mortar or blocks/mortar then finish the surface with a cob mixture. Earthbag functions best where the entire structure is under compression. That means arches, not flat spans for example.

For (2) if scrap wood is available you could build forms to support the structure till complete. The other alternative would be to use tamped earth infill, lay the arch interior over it till complete then dig out the infill.

Good luck on your project.

hello everyone.
new to everything but was reading about this round structures with cob,etc. I watched a video ,cant remember where,but the homeowners decided to build their round structure with aircrete. concrete infused with soap and air. it makes it very light,and alot of projects and housing has been built from it.

Didnt know if any of you have experience with this?

thanks for reading
loren

Hi Maggie,
It's a lovely stage you're at, dreaming up spaces and figuring out what you want to do:) I know polish weather and I'm an architect. I'm not sure cob has the insulating capacity to withstand the kind of winters you get. Once it heats up, the thermal mass makes for a nice enough inside temperature, but you still need to keep the stove running all day.. Adding outside insulation to an earthbag dome.. can be tricky.
Cob has been used as a traditional material in Eastern Europe for ages, BUT people where cold. (I am writing this from my 16 Celsius living room in a traditional stone house in France, so...well, you get used to it :))..)

If pointy corners is what you want to avoid, you can render the walls with a thick lime render that rounds up everything.
How about a hexagonal (or more, or any shape) wooden structure with heavily insulated infill (like hempcrete) and a thick render on both inside and outside to round up everything? Plus a cool reciprocal roof above the whole thing.

On round-shaped plan layouts: they can get hard to furnish. I'm not saying don't go for it, but be aware of that. You usually get triangular rooms with a lot of lost space that you heat up but don't use.

Rocket Mass Heaters are a fantastic idea for your weather and for your style! You can get really cozy and warm in an organically shaped nest .. heaven :)

Earthen floors (with optional floor heating) are a lovely add-on, though I'm not sure you can find that in Poland.

Also, think about bio-climatics. Where is the sun passing? Where is the winter wind blowing? Rain direction, the best view, the noise, the neighbor, the garden, these things can guide you in your first steps. The land tells you what to build.

Rose, Please share more of your earthbag building. We are seriously considering going that route. When I did cob years ago I needed to dig up clay at a neighbors. He was happy to build a road so it was a win win trade. Hopefully most of the materials will be onsite this time however. Happy building.

  OR   -   you could have a round home. Check out the link below and make sure to browse the site.

https://www.monolithic.org/homes/featured-homes/there-s-a-dome-of-a-home-going-up-on-pensacola-beach

I know, I know, it isn't cob, but it is a featherweight type of concrete with insulation on the OUTSIDE where it does the most good.

Here are plan and section of the basic Cal-Earth superadobe (earthbag) dome.
the pockets are laid out with the spring lines and centers/chain compass placement as the building process requires.  

HOW TO FINISH AN EARTHBAG HOME (PLASTER/STUCCO): Here is a guide to build a ROUND EARTHBAG HOME including the plaster for the interior and exterior:  https://www.instructables.com/How-to-Build-an-Earthbag-Roundhouse/

AIRCRETE: loren todd: I saw something on "Building Off the Grid" that sounds like what you are referring to:
Season 4, Episode 3  Hawaii Dome House
A mother-and-son team pulls up stakes from the crowded confines of Orange County to build an off-grid family commune outside Keaau, Hawaii. With the help of a skilled aircrete instructor, the duo overcomes a learning curve to make their dreams come true.   https://www.diynetwork.com/shows/building-off-the-grid-1/episodes/4/hawaii-dome-house

OR the DomeGaia fellow has lots on YouTubeDomeGaia also sells building plans for AirCrete domes and offers 5- and 10-day building workshops in Hawaii, Mexico, and Chile for anyone wanting a little bit of practice before constructing an AirCrete dome by themselves:  https://www.treehugger.com/diy-dome-homes-made-aircrete-affordable-ecofriendly-option-4858759  
 
This is a video of what can be accomplished with aircrete dome construction:  https://www.youtube.com/watch?v=4VcdwDRNPzA

WHAT IS AIRCRETE: a process where air (in the form of super fine, thick soap bubbles) is added to regular concrete expanding it by a factor of four (each bag of concrete goes four times further); plus the air pockets increase the insulation factor by a massive amount, and allows you to form "blocks " or "bricks" that are then used "igloo" style (snow domes built by the indigenous Inuits in Canada) to build the domes.  The exterior walls are best covered with a thin layer of water proof crack resistant stucco.  Interior walls can be finished with a thin layer of plaster and paint.  It is an excellent base for natural plaster.

Apparently it is critical that the density of the foam be EXACT - this is determined by measuring a set amount and weighing it.  Due to the air, the blocks are super light, and easily maneuvered, by hand, when 2x3 feet and 8-10 inches thick.  In some ways strength is compromised - a long skinny piece will sag and break under it's own weight - but once stacked and mudded with more aircrete the design of the structure makes it strong.  https://diyaircrete.com/howtomakeaircrete/

"Air- Crete is easy and inexpensive to make yourself with a small Air Crete machine called the little dragon that can be ordered from www.Domegala.com and a bag of concrete.

It is waterproof, fireproof, and insect proof. It offers good thermal and acoustic insulation. It will not rot, warp, or corrode. Unlike concrete which is hard, heavy, cold and difficult to work with, Air-Crete is easy to work with. It dries overnight and can be cut, carved, drilled and shaped with wood-working tools. It accepts nails and screws and is easily repaired. It had good compression strength to make excellent foundations, sub-floors, building blocks, poured walls, domes or whatever. It can be molded or formed into practically any shape. Air-Crete can cut the cost of conventional methods of construction by a factor of 10 for several reasons."  https://sustainablelivingcenteroregon.com/2019/02/13/affordable-housing/

https://www.domegaia.com/how-to-make-aircrete.html

https://www.landzero.com/blog/how-to-make-aircrete/

CORDWOOD/STACKWOOD BUILDINGS: Another option might be a "stacked wood" or "cordwood" style of building; to go round you would just alternate a shorter length (to the outside edge) with a longer piece that would be the full 18-24 inch length.  With your climate, this may be a much more viable option for both insulation, and access to appropriate materials.  Basically all you need is seasoned (fire wood that has sat for at least a year, under cover, to release it's moisture) wood, cut to length, sawdust and concrete.  

This site shows a host of pictures of various styles of alternative building:  https://www.pinterest.ca/hannequigley/stacked-log-structure/

This YouTube shows how to build a round cordwood structure:  https://www.youtube.com/watch?v=FR1CSMApGXg

This has the basics of cordwood construction:  https://www.accidentalhippies.com/cordwood-beginners-faq/

Rose Nicholas wrote:Hi, this is Rose.  We are currently building our earthbag home in Northern AZ.  After all the research and questions and more research, we decided on the 50/50 mix of our dirt/clay and volcanic cinders that are available in our area.  We are using Lime cement as a hardener.  Like you, we love the round shapes and all of our home will be domes.  A final total of 8.  We will be using cob, plaster and smaller individual sized sandbags to do most of the built ins.  The bags are so easy to mold into the correct shape and then cob over them.  It works very well and I have been experimenting with the different plasters and techniques to figure out what will work best.  I will share pictures as we start getting further along in the process.   Welcome to Permies

Wow guys! Thank you so much for such a great response to my post! So many great ideas and hints. I really appreciate it!

Rose, thank you for your welcome and please share some pictures as I'm so excited to see your progress