Earth Sheltered Homes (underground house)

[Olórin]

Hi all,
Long-time lurker, occasional poster. Lately, I’ve been wondering if any members of the mustachian community have personal experience with or are interested in earth sheltered housing (a home built at least partially underground).

It seems like something that this crowd would be into, given the increased energy efficiency, decreased maintenance, minimal aesthetic impact on the landscape, etc. In some ways, it’s not so far different from MMM’s intentional renovations of his new dwelling, with its large south-facing windows and energy-efficient design.  I’ll also admit that I just kind of want to live underground.

It seems there are an increasing number of builders of these types of homes (one interesting example, with which I’m not affiliated:  http://www.terra-dome.com/), though a number of people in the earth sheltered home community seem to advocate building the home DIY, which I’m not interested in.

Anyone here with personal experience with an earth-sheltered home?  Any takeaways to pass along to someone looking into building one?  Would you do it again?

[Thegoblinchief]

I am almost 100% certain rural built their own earth sheltered home, somewhere in deep south. So depending on responses, try PMing them?

[partgypsy]

I had a friend who wanted to build an earth home (called an earthship). But these do better in drier environments than where he was building (piedmont area NC). There are also issues, even though he was in the country, to get building approvals for something that was so unconventional. He and his wife ended up getting a loan and having someone build a more traditional passive solar house that has an earth berm in back, partly pre-existing partly added. Basically the house is a long rectangle. The back wall is lower and made of concrete. The front wall is taller and glass, and the bedrooms have a loft area and the open areas have raised ceiling. their "heating" is a wood stove. They have no other heating/cooling bills.
They are not wimps either. They lived for a few years on the property in a trailer with no facilities, to get to their dream of building their own house, but it was not feasible for them. I would recommend finding an architect in your area who is familiar with those kind of houses.

[tn3sport]

My initial reaction is I would miss the natural sunlight. Although I'm sure geothermal cooling/heating saves lots of money. I don't mind paying a little more in power consumption to have large windows in my home.

[DeltaBond]

My husband and I have considered this, but the cost of building one is more than that of a normal house.  We're in TN, subtropical climate, and mold would be a factor here, unfortunately.

[Olórin]

Thanks for the replies thus far! GoblinCheif, thanks for the heads up, and I'll definitely have to PM him, though I'm hoping to hear from others as well in this thread. 

I'm definitely aware that certain environments are more ideal, and I've started to get a feel for some of the challenges, so I'm still impressed by partgypsy's friends building an earth bermed home.  As far as lighting, you might be surprised at the amount of light in a well-designed earth sheltered home. I've seen a number of examples that are much better lit than conventional homes due to the priority given large south-facing windows and occasional skylights, etc.

In addition to my initial request for personal experiences, if anyone has any photos they would like to share of an earth sheltered or bermed home they were/are involved with, I'd love to see them.

[CatamaranSailor]

I have helped build two Earthships. At first, I was completely in love with the designs. I loved the idea of a self sufficient home that was built out of recycled materials. While I still believe the concept has merit I would not build one (even one of the newer designs).

While they may be built out of recycled materials, the are incredibly labor intensive. Which means you spend MORE money building them. The firm that designs them quotes on thier website that $225 a square foot is not uncommon for anything other than an owner built home.

http://earthship.com/a-look-at-the-models-of-earthships

There are other ways to do a partially bermed home that can provide all of the same benefits.

I am looking at CEB (compressed earth block) myself for the simple reason you can make all the blocks you need onsite from local materials in a day and built using tradional masonary techniques.

Bermed on the north side, the right design, built correctly with southern exposure you would end up with a wonderful place.

[LouisPritchard]

I have some friends who lived in a earth sheltered or "underground" house as we called it when we were kids. I was cool because the roof doubled as a yard, but being in the deep south it had moisture problems and even flooded a couple of times due to the drainage issues. Not something I would try in locations with lots of clay in the soil.

[CitrusFruit]

While I haven't read it yet, http://www.amazon.com/Fifty-Dollar-Underground-House-Book/dp/0442273118 is on my list of books to read.

[firewalker]

Sounds like you may be interested in the topic of "permaculture." It takes the choice of housing so as to work with the earth to a whole new fascinating level.

[Poeirenta]

We built our house to be passive solar, including earth berming the north wall and part of the east and west wall. So far (we've lived in it since October of 2014) it is performing wonderfully. We had a high of 93f today, and the house is at 77. It would be lower, but we had a contractor here all day and he was in and out a lot. We live in an arid-summer, moist-winter climate that ranges from about 0-100 degrees f.

On sunny days in the winter it was 75 degrees with no heat other than the sun. It is plenty bright, with all the south facing windows. We used solatubes (tubular skylights) in the rooms on the north wall: you get lots of daylight without the potential leaks and energy losses from traditional skylights. You can also put light kits in them.

If you get the ventilation right, mold should be minimal no matter what climate. Often you get mold where cold air leaks in and hits warm, moist air. With the earth bermed walls, there are no air leaks.

Finding a skilled, local designer was key for us.

[johnny847]

This is really cool. Following!

[waffle]

Growing up my next door neighbor had an "underground" house. I always though it was the coolest thing ever. The main house was all underground with the only windows being in the living room. The bedrooms, bathrooms, and kitchens all felt like a cave. Now I wouldn't like it so much, but as a kid going over to visit it was the best! On the top of the house they had a glass dome greenhouse kind of thing that was really cool too. You could get to it from the outside or from a spiral staircase going up from the house. With some better lighting designs I think it would have been close to the perfect house. It is over 30 years old and as far as I know has never had any major issues.

[Rural]

OP, we finished our self-built earth shelter two years ago. Planning and building were about a five-year process. Get Rob Roy's books, all if them if you can. And if you're serious, buy rather than check out of the library, because you'll keep going back to them. If you're still thinking it over, check the library.


Sunlight is not a problem in an earth shelter as long as it's designed right; I've never had so much light in a home. We get so much it's also the majority of our winter heating (passive solar heat). That takes planning and carefully calculating sun angles. In the northern hemisphere it means south facing, and our long south wall is mostly glass with an inset courtyard in the middle to get light into the center of the house. You probably want to set the house into the south slope of a hill to leave room for the south wall, or at least that's the easy way to do it.

Our earth sheltered house is in the Deep South, and one does have to dehumidify here regardless of ventilation - outdoor humidity in the 80-90% range for months on end just does that. But it's far less than we'd air-condition a conventional house. You do have to get the drainage right; that's critical.


After much consideration, we went with a metal roof about three feet above ground level because it saved us so much money on the structure. Otherwise, you have to build to support the weight of your structure and the earth on top, plus water weight for when the soil up there is saturated. So we have an earth shelter, not a true underground house. We used spray foam insulation to get far past the level of air seal and insulation we'd have gotten from burying the roof at a lower cost.


We could have built conventional for less, but we built this place for $39 a square foot (not including some interior trim which still isn't done).

[Olórin]

I have some friends who lived in a earth sheltered or "underground" house as we called it when we were kids. I was cool because the roof doubled as a yard, but being in the deep south it had moisture problems and even flooded a couple of times due to the drainage issues. Not something I would try in locations with lots of clay in the soil.

Yeah, that's something I've been worried about as well. If DW and I ever make the leap to build one of these, it will likely be in Asheville, NC, so this will certainly be a consideration.

We built our house to be passive solar, including earth berming the north wall and part of the east and west wall. So far (we've lived in it since October of 2014) it is performing wonderfully. We had a high of 93f today, and the house is at 77. It would be lower, but we had a contractor here all day and he was in and out a lot. We live in an arid-summer, moist-winter climate that ranges from about 0-100 degrees f.

On sunny days in the winter it was 75 degrees with no heat other than the sun. It is plenty bright, with all the south facing windows. We used solatubes (tubular skylights) in the rooms on the north wall: you get lots of daylight without the potential leaks and energy losses from traditional skylights. You can also put light kits in them.

If you get the ventilation right, mold should be minimal no matter what climate. Often you get mold where cold air leaks in and hits warm, moist air. With the earth bermed walls, there are no air leaks.

Finding a skilled, local designer was key for us.

I like the sound of it! I'm hoping earth-sheltered homes become more common (even if they are still their own little niche), so that the # of designers and contractors comfortable with them continues to grow.

Growing up my next door neighbor had an "underground" house. I always though it was the coolest thing ever. The main house was all underground with the only windows being in the living room. The bedrooms, bathrooms, and kitchens all felt like a cave. Now I wouldn't like it so much, but as a kid going over to visit it was the best! On the top of the house they had a glass dome greenhouse kind of thing that was really cool too. You could get to it from the outside or from a spiral staircase going up from the house. With some better lighting designs I think it would have been close to the perfect house. It is over 30 years old and as far as I know has never had any major issues.

This sounds amazing, and I want one.

OP, we finished our self-built earth shelter two years ago. Planning and building were about a five-year process. Get Rob Roy's books, all if them if you can. And if you're serious, buy rather than check out of the library, because you'll keep going back to them. If you're still thinking it over, check the library.


Sunlight is not a problem in an earth shelter as long as it's designed right; I've never had so much light in a home. We get so much it's also the majority of our winter heating (passive solar heat). That takes planning and carefully calculating sun angles. In the northern hemisphere it means south facing, and our long south wall is mostly glass with an inset courtyard in the middle to get light into the center of the house. You probably want to set the house into the south slope of a hill to leave room for the south wall, or at least that's the easy way to do it.

Our earth sheltered house is in the Deep South, and one does have to dehumidify here regardless of ventilation - outdoor humidity in the 80-90% range for months on end just does that. But it's far less than we'd air-condition a conventional house. You do have to get the drainage right; that's critical.


After much consideration, we went with a metal roof about three feet above ground level because it saved us so much money on the structure. Otherwise, you have to build to support the weight of your structure and the earth on top, plus water weight for when the soil up there is saturated. So we have an earth shelter, not a true underground house. We used spray foam insulation to get far past the level of air seal and insulation we'd have gotten from burying the roof at a lower cost.


We could have built conventional for less, but we built this place for $39 a square foot (not including some interior trim which still isn't done).

Thanks for chiming in, Rural!  I'll have to check out his books for sure as I start brainstorming this even further. The drainage and humidity issues are a big part of the reason DW and I would prefer to contract out the work, despite the fact that I enjoy DIY as a general rule. I've read a few horror stories of places leaking and coming apart around the inhabitants, which was fairly sobering.

Also, I like the metal roof and spray foam insulation idea. One question I did have: what structural building materials did you use?  I've tended to gravitate towards the concrete structures, but I'd be curious to hear a perspective on other alternatives, specifically with regard to their longevity. And I'm impressed with your cost to build!

[Rural]

On the structure, we went with poured concrete for the three buried sides, and we did contract that out - cost less to hire it done than to build forms in the long run. That's on a slab-on-grade, and then the rest of the walls are framed, 6" thick on load bearing ones and treated wood on all the exteriors. That my father and husband did, along with most everything else.


On drainage, We have french drains combined with drainage pipes at the base of the walls (underground) and the berms sloped away from the house. The soil is high clay content, so the drain at the base combined with clay against the upper part of the walls and proper slope combined with a good concrete sealant have meant no water issues whatsoever. The hillside helps, too; water runs off fast, and away from the house.

[Olórin]

Very cool! Thanks for humoring my curiosity. I like that design.

Now I just need to fast forward to 5 yrs from now in the next stage of life when we can set down some roots and actually build one of these things!

[Anomalous]

I'm interested in this subject, and have read a couple books about it. The Fifty Dollar and Up Underground House Book already mentioned was one of them, and it is an interesting book with some good ideas.

Actually what interests me the most is buildings made with earthen walls, not necessarily earth sheltered buildings. They have a similar function though in making a house with a large amount of thermal mass. There are a whole bunch of earthen wall construction techniques:
- traditional adobe
- rammed earth
- earthship-style filled tires
- earthbag
- cob
- compressed earth block

I see a few advantages to earthen construction, many of which also apply to earth sheltered and underground houses:
- high thermal mass (where I live there are large temperature swings but the average temperature is pretty moderate, so thermal mass should be able to regulate the temperature pretty well even without a lot of insulation.)
- fireproof (there's only 1 vacant lot between me and the national forest, and there was recently a major wild fire about 2 miles away. If the wind had been blowing a different direction my house would probably have been destroyed.  I would not want to put up any new building here unless it's highly fire resistant. I don't know why this is so rarely mentioned as an advantage.)
- low cost of materials (high cost of labor, but I would want to do all construction myself, so material cost is the more relevant portion.)
- possibly easier to DIY than stick built structures
- free-form construction; don't have to follow a detailed plan unless you want to

The biggest obstacle I see is building codes. In my county it would be almost impossible to get a permit for any unusual construction method. I'll consider moving to somewhere more lenient after FIRE...

I would like to try building a small outbuilding using earthbag building techniques some time. A structure under 200 square feet doesn't need any permit here, so that avoids the legal hassle. It would serve as a test case to see how much work this really is, and if I would want to build an entire house this way in the future. I've tested the dirt in my yard, and I don't have enough clay content, so I'd either have to buy dirt or mix in something to stabilize it.

Earthships are intriguing and inspiring, but very labor intensive. They're both earthen construction and earth sheltered. If I ever build my own house I'm definitely borrowing some of their ideas, including the greenhouse in front with plants used for graywater treatment, and the convective cooling system that uses buried air tubes to cool the inside.

[Rural]

I can't remember why, but I decided for some reason that Earthships were wonderful in dry climate but not really suitable to the Southeast. I assume it had to do with humidity. I can look up Earthships again to try to see what I was thinking if you guys are interested.


...wait, are they rammed earth? If so, I determined they wouldn't work for us because of the extreme amount of work involved and the age of the available labor pool (too damn old, all of us). That's a big part of why we didn't go for dry stacked, surface bonded block, too, that and good, cheap locally available concrete. The block is much more DIY-friendly.


Hay houses are also very interesting but absolutely a terrible idea here because of damp, mold, and rot. Exposed earthen walls ditto, but because they would dissolve over time.

Fire resistance is a fine thing, I agree. We border national forest, too. Our roof and three sides won't burn, so we have limited protection, but I'd say it's our biggest point of risk.

[Bracken_Joy]

Doesn't this seriously increase the risk of Radon in the home? A relative of mine ended up losing a ton of money into their home after their daughter got leukemia- I guess the docs determined radon was a major factor, since they had super high levels.

I don't know much about it though.

[Rural]

Doesn't this seriously increase the risk of Radon in the home? A relative of mine ended up losing a ton of money into their home after their daughter got leukemia- I guess the docs determined radon was a major factor, since they had super high levels.

I don't know much about it though.

All depends on the rock formation you're sitting on, but also three of the five radon-resistant construction features the EPA recommends (gas permeable layer, plastic sheeting, and sealing and caulking of the foundation/slab) are really necessary to leakproof an undergound house anyway (any basement really, but you care a lot more in an underground house).


http://www.epa.gov/radon/pubs/hmbyguid.html#1.a.

[Anomalous]

...wait, are they rammed earth? If so, I determined they wouldn't work for us because of the extreme amount of work involved and the age of the available labor pool (too damn old, all of us). That's a big part of why we didn't go for dry stacked, surface bonded block, too, that and good, cheap locally available concrete. The block is much more DIY-friendly.

Yes, Earthships are the ones that use old tires rammed full of dirt using sledge hammers. Extremely labor intensive to build. They do have the advantage of being able to use any soil type.

The earthbags that most interest me are plastic bags filled with a suitable soil mixture, stacked up and then plastered over. Barbed wire is laid between each course of bags to keep them from sliding. Each bag does need to be tamped down, but it's supposed to be a lot less labor intensive than the earthships with their slegde hammers. The dirt hardens into big bricks, and in combination with the plaster on both sides holds the walls together. The plastic bags only serve to contain the dirt while the walls go up, they have no structural purpose after everything is assembled and covered. You do have to have a good ratio of sand to clay for the tamped bags to harden into bricks. This is similar to rammed earth and compressed earth blocks, or to adobe and cob except without the straw mixed in.

[jalich]

If you haven't given it a read, the "Off Grid Story" by Lisa and Mike is well worth a read. It's verrrrrrrrrrry detailed, and is the story of a couple building an off-grid earth berm home in Tennessee. Their whole site is pretty good actually.

http://mikeandlisaworld.blogspot.com/p/our-off-grid-story.html

Seriously, this is worth a read if you are even remotely considering it.

[jacksonvasey]

You might want to check out Paul Wheaton's site: http://www.richsoil.com/wofati.jsp

He has basically taken the '$50 and up' concept and put his own spin on it.  The principles are mainly to build into the hill in such a way that water doesn't become a plague on you, and have a ton of dirt on the roof as thermal mass.

[dilinger]

Earthships always intrigued me, but the labor involved just seemed like too much.

Folks should check out the passivhaus standard.  It's a certification process that focuses on minimal energy use (for heating, cooling, and electricity), as well as comfort (great ventilation, etc).  There's flexibility in how the certification is handled, so one could theoretically rely on passive solar heating.  However, the majority that I've seen (and there's one near my house that I've visited) rely instead of air tightness and lots of insulation.  When you have good windows and good insulation, you can heat the entire structure with a very small heat source (like a space heater, or a human).

http://www.passivhaustrust.org.uk/what_is_passivhaus.php

[Rural]

Another thing I realized I should mention to you, OP, if you're thinking of a metal roof: termites.


In this region, you've got to be sure you don't let any vegetation bridge the gap between berm and roof (roof trusses are untreated wood unless you build your own, and nailed homemade trusses are not as sturdy as machine-pressed manufactured ones). Tall weeds are great termite climbing areas.


Assuming you leave exposed rock or something on a few feet below e roof, be sure you set up a termite barrier at the base of any insulation out there and still check regularly for termite tunnels. Professional treatment is probably a good idea.