subterranean homes

[hrspwr]

 I clicked into the housing category and nothing showed up,so I thought I might start something on subterranean dwellings. My long term goal is to homestead in the sunbelt and build a nice underground home. I want to have three sides of the house below grade, one facade [entrance] at grade. I don`t want the roof underground but maybe 1 to 2 ft above grade. The roof would be standard truss construction sheethed and sealed. The roof would actually support a large PV array and active solar heating system. The roof PV and collectors will shade the roof in the summer,bonus. I would also like to use radiant floors on geo-thermal for summer cooling. I am a self employed master plumber and want pipes everywhere. If anyone would like to exchange ideas or experiences please share, thanks.  

[chibear]

I have been in a couple earth sheltered houses. The biggest problem for the owners has been waterproofing, mainly in the roof. Since you intend to use a "normal" roof, this should not be a problem. Since you are in the sun belt, I would suggest you consider hefty roof insulation, possibly even R60 &/or look also into radiant barriers.

Concerning using your radiant floors for cooling, I have researched this with some professionals. They state 2 problems: (1) the cooled air will have a tendency to pool at floor level, so for it to work at all you would need some sort of fan circulation; (2) if you live in an area of normal or high humidity, there is a possible problem with condensation on the cool floors.

I am no master plumber, but was able to set all my radiant tubing myself with little hassle. The biggest help I found was an uncoiler, which you probably already have. It will just be another day in the job for you.    

[Peppyy]

I live in the Northeast and designed my own radiant heating system with a wood doctor outdoor wood furnace and love it. As far as cooling with radiant goes I would think you would have to have the radiant system overhead, since cold falls instead of rising. I would be concerned with condensation on humid days. I wouldn't want to have it rain in the bedroom on a muggy night.

Another person I know that heats with an outdoor furnace in the winter took a tip from my Dad and ran several coils of pipe in the bottom of his spring fed pond. He utilizes the same hot air system and heat exchanger in the summer but instead of running the water through his furnace he runs it through the coils in the pond. He clams to have excelent results this way. The only problems I foresee with this setup is the amount of power it takes for the fan and circulator pump.

My Dad uses the radiant tubing in the concrete slab in his garage to cool the water in the summer and runs it through his wood doctor which acts like a resivour. It works pretty well right into august until the slab warms up too much. Hope that helps.

[zingaro]

With the abundance of "popcorn" styro insulation around on my dumpster dives: Would not that be a great source of insulation in the cavity of concrete blocks? Im above ground at present but im diggin` a hole...soon      z

[chibear]

Apparently a lot of that "popcorn" packing is not styro at all, but some sort of biodegradable (& aparently edible) stuff. I tied using it on a previous project & the mice just loved it. They ate all of it (<> 10 garbage bags full) over the course of a winter.

[underground renagade]

I too have an interest in going underground.Presently live in a 600 sq ft cottage I designed.Has vaulted ceiling & in floor hot water heating.I have been looking at salt box type plans. Like you I only want the south face exposed. I want it to completely blend into the surrounding landscape so it will be built into southside of a hill with a sod roof.Floor plan is open with loft.Will have grey water system ,composting worm toilet,inside greenhouse & wood heat.Favor solar for power as is easier to constuct but wind would be more feizable as I am in NW Canada.

[hrspwr]

 I thought about the sod or earth roof and liked some of the benefits, especially the fact that with an earth roof the structure blends into the terrain. The problem I had is that that style roof adds so much to the construction costs. A roof capable of carrying at least 12 inches of earth is going to use a lot of steel and reinforced concrete, and then there is the problem of that earth becoming saturated. If money was not a concern I might consider it.

 The chilled radiant cooling system would only be effective If we move to the southwest US, with the low humidity there the condensation problem is pretty well solved.

 I liked the idea of a grey water tank and had even taken that another step. The house sewer line will discharge into a 2 compartment septic tank. The first tank chamber will let heavy matter settle and the second will be effluent. The effluent will flow downhill into at least two ponds filled with plants that thrive in wet environments. After the second pond that water can be pumped through drip systems for irrigation to trees or other decorative foliage.

 I like the idea of living underground and there are a lot of benefits, energy efficient, less prone to disaster-man made or otherwise,low inital construction costs compared to a complete above ground home - only buying a basement, and they are cool.

 There are a lot of good products on the market today that make these homes more comfortable then they were ten or twenty years ago. Solar reflective tubes, pre-assembled concrete forms with insulation, better glass, cheaper PV, and cost effective construction techniques make these style homes very attractive.

[chibear]

Have you considered composting toilets? This would leave you with only grey water to deal with and probably cheaper than your septic to ponds idea. We are now on a holding tank, since we are located on the lake front, but have bought a Sun-Mar unit to be installed in the spring and are hoping to eventually use the holding tank only when entertaining large crowds.

[stickalose]

  I've been building a passive/active solar house in southern Wyoming. It is bermed on 3 sides with a metal roof. The pv panels are mounted above the south windows and shade them in the summer. This works O.K. and they are easy to service. The best thing I discovered during this whole project was earth tubes (cool tubes?). Anyway I put this in to offset ventilation losses in the winter (bathroom, range hood, etc) but was surprised at how well it worked in the summer for cooling. With outside air temps 80 deg. the intake air was 65 deg. My only regret is that I didn't make the system bigger. If I get the chance later I'll add another on the opposite side of the house.

   As part of the heating system there is several hundred feet of 100 psi poly run in concrete floors. I've used this stuff alot for other things and don't have any concerns about using it at about 100 deg and 10 psi. I have some hot water panels that will heat the transfer fluid with a propane water heater back up. Also plan to add power dump from my wind genny into tank.

[hrspwr]

Thanks for the input about the cool tubes. I had always wondered about those and the possibility of mold formation in them. I am glad to hear yours are working fine. Your home sounds just like the one I would like to build right down to the steel roof, a steel roof sounds great in the rain. May I ask what the construction costs came out to be? I estimated mine to come in at 60 to 80k under roof, 1800sq ft + -, plus pv and other mechanical equipment. I estimated high on the concrete for the poured walls and slab figuring extra for a remote site. I also added 10k in there in case I hit rock.

 I did a bit of research into the composting toilets and was not sold on them. The model I looked at cost $1200.00. A big septic tank costs around $900 delivered. I was also not interested in dumping the tray under the toilet every couple of weeks. Maybe the wife will dump the tray but I doubt it. I am not knocking these toilets I just don`t see the economic benefit of having one unless you do not have the means or soil for a conventional septic.

 I put a tankless water heater in my current home about a month ago and I will definitely be using these from now on. It is LP and has dropped my electric bill by 30%. This unit makes its own spark and only runs when the hot tap is turned on, a very slick system made by bosch/aquastar. I read about this heater on this site and would recommend one to anybody thinking about building new or upgrading their systems.

[stickalose]

  I really am  afraid to calculate how much this thing cost. 2 semi loads of concrete block, 2 redi-mix loads for footings, steel roof beams salvaged, lots of Q-bond for dry stack walls, also lots of portland cement, 30 yds gravel, mined sand in the back yard. Home brew cement foam pumped between beadboard and metal roof skin quieted it down quite a bit during rain, stiffened the skin, filled voids, added a measure of fireproofing.

  Lots of loads in cement mixer.

  About $15K for elec. system, partially offset by state grant. Off grid.

  Also have tankless propane water, agree with you-they are great.

  Was also concerned about mold in cool tubes, but the humidity here is usually pretty low. The tubes themselves are 4 in. corrugated poly drainage tile (non-perf, Home Depot about 30 cents/ft.) with 6 parallel runs about 70 ft. long, 6 ft. deep. Thought about putting swamp cooler inside after air comes in but the air is cool enough, just wish I had more volume. 12 or more lines would have been better.

  This whole thing has been a pay as you go project, so its taken a long time.

  Youll have some excavating equipment around for the structure, so that would be the time to put in septic system. I have an old ford tractor with a bucket so was able to dig into hillside for house, but hired a backhoe for  septic, graywater, and cool tubes, about $800.

[hrspwr]

 I was planning on leasing a backhoe for site excavation, I operate one in my job now. I also have a Ford 1910 4wd tractor with loader but that is a bit too much for it.

 Have you been through winter yet? I have never been to Wyoming, the pictures look nice but I have heard that it can get very cold and snowy out there. I would like to know how your heating system held up and if you had to do anything extra for snow loads on the roof.

 I was planning to do some trombe walls inside the southern facade with stone. I figured the stone walls inside the house can add some beauty and defense if positioned correctly. They can also provide heat after being in the sun all day.

 You mentioned that you were able to pull sand from the backyard. I was wondering if your soil around your home is the same and if it has led to any saturation problems with the walls. I was planning to do perimeter drain tile to daylight but may rethink that and add interior drain tile with a sump pump for backup. I didn`t want to add another mechanical system if I didn`t have to.

 I have been building houses here in Maryland for over twenty years and seen enough to know that underground homes are superior. The stigma attatched to living in a underground dwelling has to be what is slowing the development. Most folks don`t understand how efficient underground is versus stick building. People must think that these things are like caves or groundhog holes. That couldn`t be further from the truth. Unfortunately people around here build houses that try to impress people instead of building smart.

 I really like the looks of a log cabin and was going to try to bring some of that style to my design. I was going to use a log or timber gable as the entrance into my home with some log and stone fencing outside tying it all together. Underground homes only look like bunkers if you want them to look that way.

[stickalose]

 Where I live is considered high desert. Been out here for 20 yrs. Not alot of snow, rarely falls vertically because it is usually accompanied by winds from the north. The top level (split level design) is usually blown clear and the diverted wind from the PV panels keeps the north half of the lower level clear. The south half piles up to about 3 ft. sometimes. The roof is good for 35 psf, haven't noticed any weakness yet.

 Still a work in progress. Last winter with only passive solar it never got below freezing inside, outside temps sometimes -10 and worse. Added a temporary 20,000 btu propane space heater this winter and using foamboard over the windows at night. Right now it is 10 deg outside and 65 deg inside with heater off all day. Today bought 30 gal propane water heater for solar radiant backup. Radiant system not yet complete.

 The soil here is mixed. It is an alluvial basin, and changes from site to site. Where the house is it is more of a sandy silt. Like you I was concerned about soil saturation against the walls, did add perf pipe along footings into subgrade gravel pits.  The hole is open anyway, why not? Backfilled with sandier soil. When time comes for landscaping will bury sheet plastic horizontally around outside perimeter about 4 ft. wide. So far no problem. For sealing wall, Q-bond mentioned earlier is fairly watertight, also have added a 30 mil pvc barrier on outside.

 Having problems now with condensation inside windows. So far only single pane, still too much fresh concrete.  Need more ventilation, needed anyway because radon is 6 picocuries/liter, vs. 4 recommended max from EPA.

 Been told the place looks like a school. Form follows function? Don't care.

 For wood front, keep it out of dirt.

 Plan "A" was to use trombe wall but it limited emergency egress as I had it, so I didn't. It's a cool idea.

[hrspwr]

 65 degrees inside with heat off, awesome. I wonder if the cool tubes are adding to the radon problem?

[stickalose]

  I don't think so, tried to keep tubes below ground leak-proof. The air intake is 5 ft. above ground. I think the source is natural materials and as yet bare earth in a couple of rooms. Will test again after floor is complete and sealed. 4 mil vapor barrier is under completed floor sections...  A friend in town tested her finished basement and it was 8.

  I think anyone building earth sheltered or underground should be concerned with radon, mainly because of air tightness. The gas is pretty much everywhere at some level, and stick houses allow it to dissipate more easily.

[trophyjim2]

I just bought a farm with a solar house on it. About 5000 square foot structure. The place is amazing with a glass front, 3 car garage, oak floors, nice wood work, and Fireplaces I need to figure out how it operates, but it should be fun. I've got a ton of history on it about the construction and about the builder who lived there. Real neat!

[hrspwr]

Congrats on your purchase TrophyJim2. 5000 sq ft is a good sized structure. That is a lot of space to heat, let us know how the solar is working for you and where you are at.

 Stickalose, you are right about the radon being a concern. I would definitely want to take another reading once you have your floors poured. On a tightly insulated structure air circulation can not be overlooked, a few small exhaust fans maybe enough to keep things in healthy levels.

 Some of the newer skylights open and close automatically with temp sensors. These could be a big help in the summer. In winter you could operate them manually for some fresh air.

 Most lower end underground homes, like what I can afford, don`t have enough cross ventilation. I have been thinking about this a lot and have come up with some ideas for using attic fans on opposite ends of the house to help move air in and out of the building. The problem I see coming is that this could bring in too much cold air in the winter. Anybody up for some other ideas?

[chibear]

Sounds like you're looking for a heat recovery ventilator. I've priced them up here in Canada and the cheapest one I found was over Can$500 and that's contractor prices. Pretty pricey stuff. I haven't started researching home-building a unit, but it should be possible, though probably not as compact as the commercial units.

Back on my reply to you concerning composting toilets. If you are still at all curious, check out Sun Mar. They have a flow through unit (the one I bought, 3000 series I think) that automatically dumps the finished compost in a bin. I don't know which unit you looked at, but the two units available up here (Envirolet and Sun Mar) need to have the compost drawer cleaned only a couple of times a year (crap is mainly water). The cheapest we can get septic tanks here is around Can$1 per gallon and code requires a 1500 gallon tank. When considering your costs for your septic system consider if it is going to gravity or pump-out, the plumbing to the tank, the pump if necessary, and the water lines. Also the cost of the field and the fact that the field will need to be replaced several times in the lifetime of your house. Up here maximum life of a professionally installed field is around 20 years before it starts leaking above ground (heavy clay soils here). On the other hand the composting toilet requires minimal plumbing, some units use no water except what your body puts in. There are basically 3 parts to wear out: a fan, a thermostat, and a heater. The fan and thermostat are cheap and easy to replace, the heater a little more expensive & a little bigger job. Don't get me wrong, these units do require some servicing, mainly in keeping the moisture levels in optimum composting range. I know I sound like a salesman, but just wanted to clarify the subject for you. If you're still interested, check out my diary in spring-summer 2005. I will give a detailed account of installation and operation of my unit.

[Jeep]

Hi

My home is called an 'earthshelter' It's about 960 sq.ft. with light tunnels on the sides that allow more light into the home. The front of the home, (south facing) is exposed to the elements, with the rest buried under a natural hill. I just bought this place about a year and a half ago. Held up in the 6.5 earthquake we had a year ago! Never have given much thought that I have a pretty unique home. It's just now dawning on me that I actually live here. The home is on 22 acres, my own land!

[liberty1]

If you are still interested, there is an architect who designed an arch supported dirt covered house.  He borrowed pipes for heating and cooling.  He used plumbing pipes rather than drain pipes.  If you use those and use a modest pitch for them, water will drain out rather than grow mold.  He tried using one large pipe (looked like 6") and found that several small pipes (look like 1 1/4") worked better.  He referred to the pipes ready to burrow as a plumber's nightmare - so you should love his design.  :-)

Another interesting point was that he felt water in the pipe field was a problem, so he put dirt over the house, then plastic, then dirt, etc until he had three layers of plastic and 4 of dirt.  The pipe field started about 1 foot from the house and there was a pipe every 6" - about 5 pipes.  The plastic sheeting covered both the house and the pipefield.

Even if you want to stay with your metal roof, you could dig an extra wide excavation,  put the pipes away from the wall like he did and put plastic just over the backfill area so the soil around your heating / cooling pipes stays dry.

He reported that it needed no heating or cooling, other than that provided by the pipe field, to stay at 70 F year round.

Bobby

[newguy]

there is a underground house where i live

its like a quancet those half round steel buildings only

its underground the south side is open with windows

the guy has a cool tube or whatever goes air intake goes down

10ft then into the house he used pv panels its pretty cool

there another guy here building steel homes but he uses geothermal radiant

floor heating the tubes are placed below the frostline and a pump circulates the

stuff in the tubes says its cool in the summer and warm in the winter.

[judyofthewoods]

Earthships are a great concept for low-cost earth-sheltered building. They are built with disused car tyres and drinks cans. Don't be put off, the finished result is quite attractive. This is the website  www.earthship.net .  I would highly recomend the earthship book trillogy on how to build one and on details, including such things as greywater planter, solar (oven-like) toilet, and mass cold air/12V refrigerator. Even if you don't want to build one, there is a lot of stuff in those books which can be adapted for other situations, and a one-stop shop for ideas on autonomous living.

[Tippy]

Im with you, the underground thing is where its at. I have a degree in architecture, and  i believe that even here in our harsh Texas weather we can design places to live that are totally comfortable, with all energy derived from the earth.  I have built a few wind generators, worked on adobe with the Tarahumara, and and learned some good stuff from them about thermal massing with earth and water.  

Anyway my project here for me and my girl is this, we got a little farm, 4.7 acres, but it is in town, the town grew around the farm.  it has a beautiful old wooden house, that im going to fix one day, but for now im setting up a "barn" to live in.  

I am building it all from junk, i have a 50' Spartan Imperial Mansion, a 30' Century mahagony clipper 300' of 25' wide salvaged hog houses, free hot tub, ect.  

I spent the last two weeks putting a school bus motor into a gradeall (we use it to load logs into the mills) so now i have free unlimited digging.  And there is a a one acre pond on the place.

Underground rainwater catch cistern, solar/compost/fire hotwater, raditant heat/cooling tubes, 12v wind gen, and compressed air wind gen.  

I got some theroies about how im gonna tie it all together, but any help from anyone who has done it would be great.  

[royalflushsheri]

My husband and I are also looking for subterranean home designs to build one for us to live in and he happens to be a Master Plumber too so when I saw your post I had to reply!  We live in AZ and I cannot find any designs online for subterranean homes.  Can anyone provide a link or web address for home designs?  There are so many things to consider from reusing the grey water to how to become totally green even just how deep to build.  After seeing the "I am Legend" movie I am more determined than ever to build this house so we can ecome fully self sustaining if need be...Anyone knowing where I can find designs and info, please reply.  Thanks

[spinningmagnets]

One required stop is "builditsolar.com" so much more than just passive solar homes.

Many things can be added after a subterranean home is built. The only other thing I can suggest is adding a french drain to the foundation in the beginning. Soil layers (strata) can alternate types. The water table got its name because when rain and snow melt percolates down through soil, it will hit a low-permeability layer such as silty clay. Then the water spreads out in a flat layer.

Waterproofing the outside of a foundation and the west/north/east walls is important, but if moist soil is up againt it, you will eventually be disappointed in the sealant ageing and slowly decaying and allowing moisture in.

Create a path of lower resistance by taking the flat soil pad before pouring a concrete foundation, and making a trench on the W/N/E sides, with the west and east runs having a downgrade to the front of the south-facing home. Lay in cloth (to prevent silting) gravel, perforated pipe (dry fit, no glue neccesary, after all, the pipe has holes in it), more gravel, then a top of cloth.

the entire "U" shaped void should be outside and below the foundation to create a flow path, always keeping the soil against your floor and wall dry.

Pay the extra to put the radiant heat tubing in the floor. Even if its not hooked up at first, its there for later.

Best of luck, and please post your results. Your real-world results are worth a dozen college theories.