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Living Underground (literally)

Nuke's picture

Ok, need to exercize some of those gray cells between the ears. I am curious as to what are some of the construction techniques employed for building a living space that is completely under earth. I've seen shows about weird/strange homes, but they've focused on caves and walk-out earthen home designs.

I am curious if anyone cares to talk about homes completely under the ground, as opposed to being walk-out types. Being that I was born and raised in New England, where a basement is surrounded on all four sides with earth, I wonder if anyone has come up with designes for homes completely underground.

And while we like to be able to look through windows at the outside, how much time do many people actually do this, as opposed to getting sunlight, the weather, etc.? With this in mind and with increasing more sophisticated technologies, both in construction and in amenities, I wonder how 'comfortable' some could get before being carted off to the funny farm for isolation-induced mental breakdowns.

I ask all of this not because I have a real interest, but more along the lines of reflecting on science fiction literature from my youth and the concepts Isaac Asimov brought to my mind in Caves of Steel. Looking at the idea, one could save on siding, windows, etc., but the savings could wind up consumed in reinforced structure (to support the earth above) and other unknowns (to me).

(post #100110, reply #89 of 105)

Wasn't Rob Roy the guy killed when his house fell down on him?

maybe you're thinking of Ken Kern? - 'the Owner Built Home' -

quality information -



"there's enough for everyone"
"there's enough for everyone"

(post #100110, reply #94 of 105)

You're probably right.  Both names are familiar from the alt arch lists, but I haven't read either.

PAHS Designer/Builder- Bury it!

PAHS works.  Bury it.

(post #100110, reply #96 of 105)

"Ken was always experimenting with new and better ways of building. A stone mason at heart, he often pushed concrete and rock to its structural limits. He's gone now. He died when a concrete slip form dome house collapsed during a freak wind storm. He had just finished it and wanted to spend the first night in the new structure."



 "knew I would have to explain the remark. Ken Kern wrote a series of
popular books during the height of the back-to-the-land movement, circa
1975, starting with "The Owner-Built Home." In fact, he wrote so many
books derived from that title that it began to seem like a joke to me.

How he died: He was sleeping alone in an experimental structure he built,
(I believe it invovled PVC pipe, plastic and soil) and during a rainstorm
it collapsed on him."


I wasn't aware it was a concrete slip form dome.


'Nemo me impune lacesset'
No one will provoke me with impunity

Edited 1/9/2006 1:12 pm ET by razzman



'Nemo me impune lacesset'
No one will provoke me with impunity

(post #100110, reply #90 of 105)

A couple people mentioned back a ways about buildings in this area that were built by piling up dirt, concreting over that, and then digging out the dirt...

When I first moved out here, I had a similar plan. When I first came to this forum, I discussed it a time or three here...

I was going to collect cutoffs from the local pallet and joist manufacturers..

I was going to "brick-lay" up a dome with short pieces of lumber. Kind of like that round stairway that Rez keeps showing, made of short pieces brick-laid.

Lay at least 3 layers of 6 mill plastic over that. Shingle lapped.

Lay a rebar mesh over that, suspended with rebar chairs.

And form the concrete over that. Mix by hand to almost no slump, and basically form the entire thing as if doing a sculpture, a bit at a time.

Then go inside and use a grinder with chainsaw wheel to smooth out the inside face. Or simply form a new face inside with lath, and drywall. Or even leave it be, and paint or seal it...

Labor intensive. Can be done a little at a time. Probably about as cheap as can be.

Rudeness is the weak man's imitation of strength. ~~ Eric Hoffer


It's a small world. Until you have to walk home...

(post #100110, reply #95 of 105)

Labor intensive.

Tired me out just thinking about it.  <G>

You touched on a major point in alternative architecture, whether you account for owner/builder labor.  Many don't.  I do.  Makes a huge difference in what you consider "cheap as can be".  No right or wrong, just different.

Paolo Soleri, at Cosanti in Scottsdale, piled up dirt, sculpted to suit, and spread whatever thin shell concrete mix he used over it.  Small spans, so probably minimal steel.  Cured, then excavated and built a house under.

I find the idea of moving the dirt far preferable to your wood idea, but I've already undertaken, and amortized, the overhead of dirt-moving equipment.  If it was shovel and wheelbarrow I probably wouldn't.

Forgot to mention that your idea would fit in well on the fc list.  Probably somebody there who's already done something similar. 

PAHS Designer/Builder- Bury it!

Edited 1/9/2006 10:27 am ET by VaTom

PAHS works.  Bury it.

(post #100110, reply #98 of 105)

I notice in my library I have Underground houses by Robert L Roy isbn 0-8069-8856-8

I think that's the Rob Roy book I've got.  I was NOT impressed!  IIRC, he just has a couple inches of dirt on the roof.  Just enough to grow grass on and look really scruffy.  And the supporting structure is wood, not steel or concrete.  I can remember thinking, "no way in He11!" I'd do one of his houses.  Just begging for trouble.

Save your $$ and just check the book out from the library. 

I did like Dan Chiras's book: The solar house: passive heating and cooling.

Book Cover

It isn't an 'undergound house' book so much as a energy efficiency book.  Chiras is a little more of a tree hugger than I am, but he gives a nice overview of passive techniques and such.

An article on an earth sheltered house that was built a couple years back:

With a link somewhere in there to the company that built the structure.


"The test is to recognize the mistake, admit it and correct it. To have tried to do something and failed is vastly better than to have tried to do nothing and succeeded."
-- Dr. Dale Turner


Time is the coin of your life. It is the only coin you have, and only you can determine how it will be spent. Be careful lest you let other people spend it for you.
-- Carl Sandburg

(post #100110, reply #83 of 105)

What is the differance betwen gunnite and shotcrete?  I thought that they were just a differant word for the same thing.

(post #100110, reply #84 of 105)

In gunite, the materials (dry mortar in an air suspension, and water) come down separate hoses to the nozzle, where they mix and are sprayed by the nozzleman. Nozzleman gets finer control over the mud, but also needs greater skill to control water, air, etc.

In shotcrete, the mixed mud (often Redi-Mix) is conveyed down the hose by hydraulic, piston, or peristaltic means to the nozzle where an air hose is attached which propels the mix at pressure. Less control, and results depend a lot on the quality of the mix... as close to a 0 slump as possible. Equip is less expensive, and can often be done via rentals (big air compressor and a typical concrete pump, plus a $200 nozzle).

These are often referred to as dry process and wet process respectively. Similar, but more like fraternal twins than identical twins.

(post #100110, reply #87 of 105)

I don't see how the bottom line costs would be noticeably different.

My suggestion would be to total man hours and material for a Monolithic.  It all adds up somewhere.  Either there're too many hours, or the effective hourly rate is very high. 

No offense, but I agreed the fc list in not at all understanding why Monolithics were so expensive.  Not just compared to my cast-in-place (which nobody there was interested in) but to the thin shells they were doing, several commercially.  A common assumption was that Monolithic took a large cut off the top, inflating the price.  The money had to be going somewhere.  My guess is that you were painted as a Monolithic guy, ie. uninteresting.  The group really isn't cliqueish, or even particularly focused.

I regretted missing the Oregon conferences, which I understand were quite varied.  There was even a presenter there from Spokane, Don Stephens, who designs extremely green houses, hates concrete.  Cracked me up that he would bother to attend.  His Annualized Geo Solar concept (AGS), which he claims far superior to PAHS, is currently under attack from some physicists who maintain he can't get enough heat into his dirt to do annual heating.  I've never understood how it could work either, but there're a lot of things I don't understand...  He recently posted that he's "too busy" to explain. 

The Righmond failure was before your, and my, time.  Let's see...  1970, 3 high school gyms in Richmond, hyperbolic paraboloids.  Milo Ketchum was an interesting guy, investigated the failures.  His son, Mark, keeps the web site which includes a lot of pictures of various thin shells.   Restaurant Los Manantiales, by Felix Candela, is a building I find inspiring.

and a bunch of practice to do well.  

Exactly.  One of the many reasons I'll stick to annual heat storage, which you clearly aren't doing, but maybe try dirt-forming.  Bo Atkinson's done some amazing thin shell work

As you say, many ways to build a good house. 

PAHS Designer/Builder- Bury it!

PAHS works.  Bury it.

(post #100110, reply #91 of 105)

>My suggestion would be to total man hours and material for a Monolithic. It all adds up somewhere. Either there're too many hours, or the effective hourly rate is very high.

Well, I hope my listing of materials dispels the idea of them requiring extra materials, compared to what you describe. And the speed with which I've seen some built, with crews no different from what you described, dispels the idea of requiring too many hours. The ones I know some decent cost data for were very close in shell cost to what you described. I know some contractors scheduling two years out--maybe they have a demand that allows higher profit margin than some others are charging?

>No offense, but I agreed the fc list in not at all understanding why Monolithics were so expensive. Not just compared to my cast-in-place (which nobody there was interested in) but to the thin shells they were doing, several commercially. A common assumption was that Monolithic took a large cut off the top, inflating the price. The money had to be going somewhere.

Part of the confusion here is switching from your stuff to fc and back. With no fc costs detailed here, it's a bit hard to speculate. When we compare to other stuff shown in FHB, for example, we do pretty darn good on costs. And the comparison we did above showed no major differences with your stuff...I'm wondering what buildings were being compared to conclude "so expensive" and how comparable they really were.

Here's what I observed about the fc work that I saw presented in OR. First, there seemed to be little interest in insulation. The buildings shown were typically uninsulated, which messes up comparisons on both cost and performance. There was absolutely no interest in what we use, which is 3" of sprayed polyurethane foam. That'll account for a bit of difference.

The other thing I saw is that they didn't regard engineering in the same way. We're pretty manic about rebar patterns and placement, and achieve incredible strength and performance as a result. The examples of fc I saw discussed used seat-of-pants engineering (paying an engineer was an unnecessary expense, according to some), and had neither the rebar schedule nor the concrete thickness that I'm used to.

I recall descriptions of a building in Mexico where the mud over the mesh was only an inch or two thick, and was a 1000# mix at that. It was described as "good enough" as long as it supported the weight of the worker. No load standards to meet. I was sitting next to my engineer, and I think he had heart palpitations. They also described the water-proofing process as "see where it leaks over the first year and patch it." Might work in Mexico's dry climate, but it wouldn't meet typical expectations of any client of mine. That could account for cost differences.

Now, most of the builders I know gripe that we're over-engineered (one engineer told me he assumes that half the rebar will not be properly encased...such is his use of safety factors)--and absolutely are over-speced by fc standards--but I think we have a different expectation re resistance to wind events. And it's one reason the record has been so good for the air formed ones...we're observing a different engineering standard, if the descriptions I heard are accurate.

So yeah, compared to most fc, we use more insulation, more concrete, more steel. While I fault Monolithic for a number of things, they shouldn't catch any blame for this, because first, I appreciate the high engineering standards, and second, we often build without any of their products, and so they don't necessarily factor into the cost picture at all.

One other cost factor we catch that many others do not is travel...the cost of transporting equip to a site and housing a crew for 6 weeks or two months can add thousands to a project...not the life I'd like to lead, to be sure, and a not-insignificant cost.

Winding this down, are the cost comparisons on comparable projects with comparable specs? If they are, they'll show similar material and labor requirements. If the specs or standards are different, then the cost comparisons won't be valid.

(post #100110, reply #93 of 105)

Part of the confusion here is switching from your stuff to fc and back.

Jim, the reason I did was that those guys have a better handle on labor costs for what you're talking about than I do.  You haven't given any real man hour numbers.  I'm totally ignorant there, but you keep asking about your bottom line.  And I don't know of anybody who was building to your specs.  What I am aware of is that there are guys who are doing the equivalent labor to a Monolithic that were very suspicious of Monolithic costs.  As in, where does the money go?  Clearly, I don't know.

One other cost factor we catch that many others do not is travel...the cost of transporting equip to a site and housing a crew for 6 weeks or two months can add thousands to a project...not the life I'd like to lead, to be sure, and a not-insignificant cost.

This was a large suspicion of mine.  For instance, when you told me, way back when, that you had a couple of domes coming up here, it was clear that the crew was going to be imported.  This is going to greatly raise the effective labor cost.  Like I said, look at your material cost and the rest is labor- to the client.  You can talk all you want about unskilled labor, but it's what the client pays that counts.

Then you say And the speed with which I've seen some built, with crews no different from what you described, dispels the idea of requiring too many hours.  Well, it doesn't work both ways.  What is your labor cost, after deducting material?  How many man hours?  There's an answer there.  I don't have your information to figure it for you.

Cast-in-place about anybody can do.  Hell, I read a how-to book, hired two guys who knew less than I did and we made this place.  No imported labor.  Looked into post-tensioning as a bar joist alternative and quickly rejected it.  Primary reason for the high cost?  Imported labor.

You're correct about a number of fcers, like MxSteve, who built an underground vault in W. Colorado.  Zero engineering.  He and I got into it over that.  Unlike him, I have a very good feel for what I don't know (and consider it important), which is why I asked if you had specs for 300psi.

 And the comparison we did above showed no major differences with your stuff...

Right, which didn't surprise me.  I'm well aware that my costs are high for cast-in-place.  Go above grade, remove the earthload, and I can get a metal formed (and bar joist) shell down to well under $15.  That's where it realistically compares to your domes.  You mention 6 wks (or more) of crew time, that's a lot of labor (and housing for it).  Talk to somebody pouring subdivision basements, it's more like a couple of days.  Bar joist roof is on in one day.  Another to pour both slabs.  What's that- 20% of your shell labor?  The crews are smaller than your spray crews, and local. 

As you've mentioned, earth loading raises the cost substantially.  It's prepaying the heating/cooling costs-  forever.  Will it amortize?  Depends on your numbers.  Then there're guys like BB, and me, who think underground just "feels better".  Just like dome folks. 

If you recall, what I said was that I know of no alternative method (to mine) of going underground anywhere near as cheap.  Still don't.  Thin shell might, but not the Monolithic method.

Winding this down, are the cost comparisons on comparable projects with comparable specs? 

Have I answered this adequately?  I don't know cost for fc, or Monolithic, with earth loading.  Above grade cast-in-place with a bar joist roof comes in substantially less than a dome.  You want one?  Me neither.  Let's stop.  Doesn't look like we're getting anywhere constructive, but I really would be interested if you come up with 300psi specs.  Then we could do new comparisons, on underground, the subject of this thread.  I'd love it if thin shell (one forming or another) was cheaper.  And it might well be.

PAHS Designer/Builder- Bury it!

PAHS works.  Bury it.

(post #100110, reply #99 of 105)

Let's dispel a few things before we stop. Some things have been put out there that I don't wanna let stand as such.

First, I'm not in a position to defend MDI's costs. And the people saying things about their costs aren't here to represent their own costs fairly. MDI has never built one of my designs, so I have no clue what they really charge for construction, except that my clients have always not chosen them when it's been bid out. Most I've used of theirs is an air form, but more often than not the builder chooses a different air form, too. Let's keep them out of this be/c they aren't here to explain their costs...hell, for all I know they have such a high demand that they can charge a premium. Good for them if so! Or maybe people questioning their costs aren't comparing comparable structures--no fc structure I've yet seen is a fair comparison, be/c the specs aren't nearly the same.

I've given the hours for rebar, shotcrete, etc that we use as a budgeting guideline, and they're from an industry spreadsheet. I don't have a specific hrs or cost breakdown for a plain 2k house be/c I've never done one of those, sorry. My designs include a bunch of sculpted elements...dormers, cutouts, canopies...they take a bunch amt of time and screw up comparisons. They easily turn a couple or few week shell build into a coupla month fine homebuilding project. Not at all fair to compare that to a few poured walls. Our typical shell takes the time I mentioned be/c we're including elements that aren't covered with just metal forming and bar joists. To compare to what was described of the CIP structures, I'd have to cut a bunch of elements off my designs or find one done with no adornments, such as a storage dome, and in leiu of that, I make some guesses. The figures I gave you would be enough to calc a simple shell cost and timeframe.

>Go above grade, remove the earthload, and I can get a metal formed (and bar joist) shell down to well under $15. That's where it realistically compares to your domes.

And it's rated for 200+ mph winds? And 2500 psf loads? And insulated? And as low in energy loads as we achieve? Bull. We aren't gonna compare an above ground concrete box to a house with sculpted eyebrows, canopies, insets, the best insulation, etc. and call it realistic.

Geez, our stuff covers a huge range, and can't fairly be lumped under a single "domes". There are stadiums, intricately sculpted luxury houses, survivalist structures, storage sheds, and much more. If we're talking about a shell for storage, which is the closest thing to the CIP box described, there'll be a different set of economics than for the houses I design. My houses do not realistically compare to metal-formed, bar joist shells...that's bordering on insulting. If you want to compare to your $15/sf, we'll toss together one with no insulation and a reusable air form...I don't have those costs be/c that's not what I do, but there's no reason to think that with much less concrete than CIP would use, it wouldn't be the same or lower cost. The only reason I don't have hard numbers for it is that there's not been a demand for that aesthetic.

>The crews are smaller than your spray crews

You keep saying that, but it's not true. My house had a crew of three, often two, and sometimes four. The one's under construction now have crews of 4 each. Some of them use local labor and some don't.

And if you're gonna hit on labor not being local and high costs and specialized labor despite all I say to the contrary, I'll focus on the many people who are building these completely on their own with crews of two and all local labor and equipment. I haven't focused on that here be/c that's not my business designs are for finely-built and luxury houses, and I focus on the few contractors doing that consistently. But people are building these with the same home-grown approach you used, and achieving fine results without any travel or high-value labor, so let's keep that whole travel issue in perspective. There are only a few traveling crews, and they tend to focus on the most elite houses and largest stadiums, where experience and quality and detailing are the primary considerations.

>As you've mentioned, earth loading raises the cost substantially

Did I say "substantially"? I've looked and couldn't find it. I just said it's an _additional_ cost to move the dirt around with little commensurate benefit for us. I'm running $40-$80/m for heating or cooling in season for 6000+ sf. I don't have a whole lot to gain with earth loading. Now if it were required, we could easily do it. Simply do the shell without the foam...everything else the same as PAHS...and note that I said earlier that I liked the PAHS concept...just haven't had the call for it.

>Thin shell might, but not the Monolithic method.

By thin shell, do you mean fc? Be/c the air formed method IS thin shell. Inflate, rebar, spray. Less material, same labor. What's the big deal? There's no reason to think they wouldn't be comparable, with the dome providing unequalled strength.

>but I really would be interested if you come up with 300psi specs.

I assume you mean 300 psf...that's what was in earlier posts.

A typical hemisphere, as I've mentioned before, will use about 2# of rebar/ssf and 4" of concrete. I was actually overly generous, be/c it'd use 4" of concrete for just the first 8' or so and taper off to 2.5" overhead.

I did reach my engineer today. To merely satisfy a 300 psf spec, we would have to REDUCE the concrete and steel substantially. The building described in the prior paragraph, with #3 and #4 bars about every 12" and the concrete thicknesses listed, would, with no further modification, provide for well over 2,500 psf with an engineering safety factor of 3. The limiting number is the 2.5" concrete up top. Wanna make it hold double? Increase the rebar one size and add an inch of concrete.

And I have the decimal places right...2500 psf...he said the numbers calc to over 5300 psf, but he cut it in half to be conservative.

Tom, I'm worried that the tone of this is too harsh, and I don't mean it to be, but I've spent enough time editing it. I don't wanna sound grumpy, but I also don't want misinformation out there. We have enough challenges when the information is _accurate_...

(post #100110, reply #36 of 105)

Great pix.  Yours?

first three are my daughter's from 2004 - last one I pulled off the net - she spent a month traveling in eastern europe and turkey before school in england -




"there's enough for everyone"
"there's enough for everyone"

(post #100110, reply #33 of 105)

Natural light usually is the big issue.  You either need lightwells, or you need space for "sun" lighting (the full spectrum lighting is usually hotter--temperature--and needs more space to be comfortably habitable.

The next big hurdle is in AHJs 'letting' you do this--egress requirements will make it less of an "underground" house at every turn.

The various access requirements equal penetrations in the envelope, and every penetration is a potential leak in the proposed u/g house.  And everyone, from SOs to the lendor, all want a different break in your w/p skin of the structure.

This is where "earth sheltering" (which may be the best search term to use) can help.  At least at the single-family house sort of level.  For a submerged arcology, that's a different sort of thing altogether.  (I'd be tempted to build/design that rather like a submarine, with an inner and an outer wall . . . )

Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #100110, reply #62 of 105)


The opal miners in northern New South Wales and South Australia excavate below ground to find their gem stone lodes. They convert their diggings into spacious living quarters when they are satisfied that they have exhausted the source of colour. The big advantage for them is the insulation from the fierce heat of those low humidity areas. Maintenance is not a problem for them either.

You may wish to google Coober Pedy for more info.