Knowing how to build a variety of different shelters is an invaluable skill to have. An earthbag dome house can be put together cheaply, quickly, and easily, and is ideal for any climate. Read on to learn how to build these low-impact shelters on your own property.
What is an Earthbag Dome House?
Humans have been living in dome-like structures for thousands of years. Turkish people in Harran built domed structures of stones packed with and covered in clay, while stone-age people in Ireland lived in beehive-type huts called clocháns, which were made of dry-stacked stones.
An earthbag dome house is constructed similarly to these old stacked rock huts, except the building materials are bags filled with sand rather than stone slabs.
Their consistent shape makes construction much easier, and the combination of sand and polypropylene is significantly more weatherproof than drafty rocks with large gaps between them.
One of the best things about earthbag dome shelters is that they can be made in just about any size. Additionally, you can make networks of them with little tunnels to connect them, or have several of them dotted around your property.
Some people use them as animal shelters, while others adore them as root cellars, but you can also use them as backyard meditation retreats, additional space to host guests, or fun little spaces for your kids to play in.
What You’ll Need:
Building an earthbag dome house doesn’t cost much, but you’ll still need to invest in some supplies. An average-sized structure may cost you between $500 and $700, depending on how many materials you already have on hand.
Additionally, you shouldn’t need any kind of building permit because these are usually smaller than standard structures, but check with your local building authority before you get started, just in case.
- Polypropylene sand bags: these often come in bundles of 200, so you can estimate how many you’ll need based on the shelter you’re building. Aim to get the ones that are about 18″ x 30″, and about three packs (so 600 bags) for an average-sized shelter.
- Several 2-gallon heavy-duty contractor’s buckets
- Heavy gravel
- Medium gravel
- A bucket chute (4-gallon bucket that’s had the bottom removed)
- Metal cutters
- 15-gauge galvanized steel wire
- 4-point barbed wire (you’ll lay this down between the layers/courses of sandbags)
- A long piece of wood to use as a center stake
- Metal slider
- Measuring tape
- Eco-friendly lawn paint
- Door anchors
- Steel mesh (optional)
- Landscape fabric (also optional)
Step 1: Make Plans
Before you even think about filling a bag, measure and sketch out what you plan on building. Determine the width and height of the earthbag dome house you want to build, and also take into account the buttresses that’ll need to flank the entranceway.
These will help to support the structure, and pull double duty as retaining walls for the earth that you’re going to pack around and over the dome once it’s built.
Also determine what kind of doorway you’re aiming for, as well as if this structure is going to have windows or not. You’ll need to take these into consideration ahead of time so you can build and place window butts out of wood (or old tires), and stack the sandbags around them accordingly.
The same goes for if you’re planning to build a balcony-type overhang to shelter the doorway from rain or snow. Draw detailed sketches, adding in as many measurements as possible.
Step 2: Prepare the Area
Now that you have a solid idea of the type of earthbag dome house you’re building, you’ll need to prep the site.
First and foremost, you’ll need to clear and level it. This will involve a lot of digging and hoeing (no pun here, honestly). You’ll need to refer back to the plan you’ve made so you know how large to make the building foundation.
For example, suppose you’re building something with a ten-foot interior diameter. Those sandbags are 18 inches wide, so you’ll need to add that much width all the way around to accommodate the bags.
Then, since you’ll be berming this structure most of the way around with soil, that’s another four or five feet that you’ll need to dig all the way around.
For the sake of ease, and because I failed math terribly in school, estimate that you’ll need to dig and flatten an area that’s approximately 20 feet in diameter (to be on the safe side) to create a shelter that has a 10-foot interior diameter.
Step 3: Create the Base
Since you’re building on top of the earth here, you’ll need to create a gravel base for your earthbag dome. This is essentially a drainage bed, allowing moisture to wick away from the shelter and into the surrounding earth.
Aim to dig down ten to 12 inches and fill that with heavy gravel. Then, use a hoe to spread it around and a tamper to level it flat.
Once your gravel is leveled out, you’ll need to draw a guide circle to lay the foundation layer of gravel-filled bags. The easiest way to do this is to use a stick and line.
Refer back to your design notes to determine your structure’s interior diameter. Tie some cord or string to a stick and drive that into the approximate center of your intended earthbag dome house.
Then measure out half of the diameter you’re aiming for and mark that on the string. For example, if you aim for a ten-foot internal diameter, the string should be five feet. This will give you a five-foot radius on either side of the central stick for a full diameter of ten feet.
Get someone to hold the stick in place and turn it while you walk around it, marking out the circumference circle with your spray paint.
Note: This gravel foundation will depend on what you’re building upon. For example, out here, we’re basically building upon the Canadian Shield, which is a massive, dense rock formation. If you’re building atop solid rock, you can simply lay down a layer of gravel, tamp it flat, and build from there.
Step 4: Lay a Foundation Layer of Medium Gravel-Filled Bags
For the gravel bags you’re going to use as your foundation level, it’s best to double-bag those polypropylene sandbags you have. Gravel is abrasive and may tear through a single layer.
Aim to fill each bag with the same amount of gravel (or sand, once you get to that step) for the sake of consistency with bag sizes.
Lay the foundation bags around the circle you sprayed, using it as a guideline for aligning their inner walls. Once these bags are in position, pack soil around them firmly to keep them in place.
Step 5: Fill Your Sand Bags
Now that you’re ready to start building in earnest, it’s time to fill those sandbags. The key here (and this is important to remember) is to wet the sand slightly before packing it in.
iUse a hose to moisten all the sand, and then test it before filling any of the bags. It should be just damp enough to hold its shape when you smoosh a handful of it together.
If the sand isn’t damp when you fill the bags, it won’t be dense enough to hold its shape. It’ll slop all over the place, and you won’t get consistent bag sizes or structural support.
You don’t want the sand to be so wet that water dribbles out of a squished handful, nor should it be so dry that it crumbles. If you can use it to build a sand castle, it’s just right.
Step 6: Start Stacking
Use your long piece of wood to ensure that all of the bags you laid down are leveled. You can do this by placing this plank across the structure like you’re measuring its diameter and placing a level on top.
If the happy little bubble is in the middle, then everything is kosher. If it isn’t, you may need to use your tamper to pat down the gravel inside certain bags to level out the tops.
Once you’ve determined everything is level, it’s time to stack the next level. It’s up to you whether you lay only one level of gravel bags. Most people lay at least three gravel levels before switching to sand-filled bags. This creates a sturdy foundation to work with.
Lay barbed wire along the center of the layer of bags you just tamped, and weigh it down with rocks or other people’s hands to keep it in place while you put down the next set of bags.
You can either place these manually, very carefully so as not to tear the bags open on the barbed wire, or use a metal slider for precision and safety. Remove the weights from the barbed wire as you move along.
Note that as you lay each bag in this level, you aren’t going to stack it directly on top of the preceding one. Since the radius of each level has to be a bit smaller than the preceding one in order to form the dome, you’ll need to overlap each bag slightly.
How much this overlaps will depend on the height of your structure, but the standard shift is an inch or two.
Remember to add to the buttress retaining walls as you go so they’re integrated into the structure rather than simply being add-ons at the end. Similarly, if you’re going to be building an overhang, you’ll need to stack the supports in between the sandbag layers as you go.
Step 7: Leave Room for a Door (and/or Windows)
Remember those designs you came up with at the beginning? You’re going to have to decide what kind of door you plan on having on this structure.
If you’re using it as a goat or sheep shelter, then you can leave the doorway open without a problem. In contrast, if you’re using it as an office or a cold cellar, you’ll need to sort out the door installation.
It’s up to you whether you create door anchors that are held in place between sandbags, or if you create a wooden frame upon which to hang your door later.
Step 8: Top it Up!
Keep stacking your sandbag layers, overlapping them as mentioned until there’s barely a gap left at the top. At this point, some people choose to lay down a large piece of steel mesh to support the last few bags that will create the roof. You don’t need to do this, but it’s certainly helpful!
Place the last bags down and step back to admire your work.
Step 9: Consider Flooring Options
The type of floor you’ll choose will depend on what you’re using this earthbag dome house for. If it’s a shelter for livestock, packed earth covered with straw that can be changed out regularly should be fine.
Alternatively, if you’re using it as a cold cellar, you can put down slate or tile flooring and grout the gaps.
Similarly, if you plan on using this hut as an office, meditation getaway, bunkhouse, or similar, there are a number of flooring options available. Tile flooring is one of the easiest to install and keep clean, but you could also use cork, bamboo, or similar. Let your climate and usage dictate your choices here.
10. Cover It
At this point, it’s up to you to decide how you’re going to finish and cover your earthbag dome house. Some people simply use plaster inside and out, which is one of the easiest and most cost-effective methods.
Others choose to plaster the inside and go full hobbit on the outside with soil and sod. You can also do a combination of this and plaster the outside, followed by a layer of landscaping fabric or steel mesh, followed by soil.
If you’re going the plaster route, keep in mind that you’ll need to pack cob in the gaps between the bags to create as smooth a surface as possible before plastering.
Do some research to determine what will be the best for you, your structure’s purposes, and your climate. If you choose the soil route, you can cultivate a green roof with indigenous perennial flowers, herbs, and grasses—which would be amazing if you’re using this as a shelter for goats, sheep, or chickens.
Alternatively, plaster is beautiful too and can be painted bright hues to your heart’s content.
As far as earthbag dome house construction goes, you can get super creative. As mentioned earlier, you can build several of these in an area for animal shelters, bunkhouses, or even networked storage areas.
And hey, if you find that you really like this construction method, you can look into building larger structures the same way! These eco-friendly, low-impact homes are a great way to build shelters of all kinds in all climates and may be as cherished by future generations as they were by our ancestors.