PSP refers to a method of building developed by Mike Oehler, who wrote The Fifty Dollar and Up Underground House Book. Mike definitely has some ideas worth relating, although they won't appeal to everyone. He did indeed build a fifty dollar house that he is still living in, although I believe he has added on a few hundred dollar wing to it. Much of the savings that Mike has been able to attain is through a combination of using recycled materials, logs harvested from his own land, and a simple method of building underground.
PSP stands for Post/Shoring/Polyethylene. The framework of the building is created with posts that are preserved in various ways and planted in the earth. These posts serve to support both the walls and the ceiling. The space between the posts is planked with used dimensional lumber, such as from wood pallets. This is what he calls the "shoring". Then the whole thing is wrapped in polyethylene plastic before it is backfilled with earth, making a truly underground home. Instead of conventional flooring, Mike advocates using the existing earth, finely raked and smoothed, and then carpeting thrown over it.
To me the most impressive aspect of what Mike has to offer is in the design concepts for building underground. He has come up with a system for designing rooms that can provide daylight and proper drainage for a wide variety of arrangements. His thinking goes way beyond what most underground architects have accomplished.
undergroundhousing.com This links to information about Mike's book and videos, presented by the publisher.
The Fifty Dollar and Up Underground House Book, by Mike Oehler, 2000.
The Earth Sheltered Solar Greenhouse Book by Mike Oehler, 2007. The author writes, "my secret is that on the south wall of the greenhouse I dig a pit down eight feet and build a walkway up four or five feet where I can walk and bend over the growing beds to work on the plants. The pit allows cold winter air to flow downward to be heated by the earth rather than lying on the plants. On flat land I'd sink my north wall and all the grow areas about four foot deep and pile the earth up on the north side leaving at least a foot of north wall exposed for ventilation "windows" that can be opened as needed. I'd put some rigid foam insulation over that mound of earth on the north and a layer of polyethylene to keep it dry and some inches of earth to protect the poly from the sun. That north mound will serve as a heat sink then, to radiate heat back into the greenhouse at night."
ASK THE EXPERT ADVICE
Links to the Ask the Experts page
Mike Oehler is the author of The Fifty Dollar and Up Underground House Book which describes his PSP system of building underground. Mike has been living in an underground home of his design for over twenty years, and swears by his methods. He has evolved some very well thought-out concepts for designing underground structures, which could also be used with other construction techniques. PSP stand for Post, Shoring, Polyethylene---the basic, rather low-tech approach to using posts, boards and plastic sheeting to build underground very inexpensively. Mike has also produced a video series that demonstrates his concepts.
QUESTIONS AND ANSWERS
Comment from Mike: I'm building a new underground house/tree house, Kelly, and have been working on it for two years now. It should be spectacular--my reply to all those who wouldn't consider my methods because they were too small or cheap.
Q: Has anyone used bags full of leaves, sage brush.. on to top of an underground house??? such that you get insulation.. toped by PE film and with perhaps 2" of sand on top to protect the PE film?? In this way you keep the weight down to very little. The garbage bags would form a tight seal.
A: I know of no one who has used bags of leaves or sagebrush on top of an underground house, though the idea is intriguing. Yes, it certainly would cut down on the weight and provide excellent insulation. I see some probable difficulties, however. One is fire danger which is absolutely not a factor with solid earth. Another is that the material in the bags would likely poke through with the weight of the sand on top, certainly through the garbage bags, possibly through the poly sheet on top. And of course you do need something on top to protect the polyethylene from the ultraviolet in the sun's rays which means weight. I wouldn't advise walking on that roof either which also means keeping the dogs and kids off, a big order. Possibly the swimming pool liner material EDPM (I think it is) would solve this problem. I'll be using EDPM for one of the layers on the Ridge House this spring. Try your idea and let me know ten years down the line how it worked. Nice question.
Q: Thanks for getting back to me.. I'm thinking as sloping the roof towards the center of the circular building.. and collecting the water in the middle.. But instead of bags of sage brush.. Bags of plastic bottles.. Overing the roof with that..then.. a plastic tarp and a little sand or maybe just use 1/2 fill bottles with sand to stop them from blowing away.... maybe painting the top bottles white..How about that??? Has anyone used capped bottles in the wall for partial insulation??
A: (Kelly) I would have some concerns about the weight of the collected water, as it can be VERY heavy. The plastic bottle idea also might work. I have heard of the use of glass bottles in walls for light and decoration...and some insulation. Let me know how it all works out.
Q: If I use Mike Oehler's method of building underground, can Ihave a bathroom, bathroom shower, washer/dryer, or just plain running water in the house without having to build a story above ground ?
A: Most likely yes. Depends on the depth of sewers, bedrock, watertable. In almost every case you can do it if you build on a slope. Adding plumbing to an underground house is no different than adding it to a basement laundry or rec room.
Q: I am wanting to build a pit type (in ground) geenhouse, but can find virtually no real usefull info on one. Building it is not the problem, I am a carpenter, but is it a good workable type of greenhouse. I have heard they are very energy efficient and I have heard they are difficult to grow in, so I don't know. What I want to do is to grow carnivorous plants, which require a fairly humid enviroment, with plenty of sunlight, yet keeping temperatures in the high 80's would be ideal, as well keeping winter temps in the high 40's. I have a traditional attached greenhouse on my home, but heating it at all in the winter is expensive, and summer overheating is always a problem. So, I have heard that pit type greenhouses need very little if any heating or cooling, if so that would be the answer to most of my problems. If possible, I would like to even grow some vegetables in it during the winter as I have heard can be done. Now,, I live in southern Virginia, I have full access to the summer and winter sun, and have anywhere on a 5 acre plot to put this greenhouse, and would plan to run water and electric to it. So, if you could PLEASE just give me the rundown on this idea, the good and bad, so that I can decide on what to do I will truly appreciate it, very much.
A: A pit greenhouse should do very well in Virginia on either a south slope or flat land. I've had them on both up here next to the Canadian border and they have taken my tomatoes into the second week in December (every unsheltered garden freezes out by the first week in October here) and takes such hardies as kale and cabbage through the winter. They don't grow for two winter months but are still alive and can be harvested. All this without heat other than the sun and earth and no thermo-pane glazing.
My secret is that on the south wall of the greenhouse I dig a pit down eight feet and build a walkway up four or five feet where I can walk and bend over the growing beds to work on the plants. The pit allows cold winter air to flow downward to be heated by the earth rather than lying on the plants. On flat land I'd sink my north wall and all the grow areas about four foot deep and pile the earth up on the north side leaving at least a foot of north wall exposed for ventilation "windows" that can be opened as needed. I'd put some rigid foam insulation over that mound of earth on the north and a layer of polyethylene to keep it dry and some inches of earth to protect the poly from the sun. That north mound will serve as a heat sink then, to radiate heat back into the greenhouse at night.
Hard to advise you on the south slope since I don't know the pitch of the slope, but again have the north wall come up a foot ot two above the surface for ventilation hatches. Always pitch your glazed roof towards the south, of course. You may get away with single glazing in Virginia. My next greenhouse will have a southern wall of used thermo-pane sliding glass door (stationary) which I've gotten for as cheap as $5 used ($300 & up new.) I'll probably glaze the roof with duo-pane greenhouse fiberglass except the very north four feet which will be in hinged plywood which I can open in the summer. I'll insulate the plywood for the winter I expect to incorporate rabbits and chickens into the greenhouse for body heat, CO2, ammonia and manure. They'll have automatic access to a pen on the outside. All earth level grow beds and critter cages will have wire mesh buried a foot deep to keep the right critters in and the undesirables (weasels, gophers) out.
Q: What is the deal on Radon gas. Mike seems to say its from the ganite in the concrete floor. Is that true. I assume the PE film would help to keep it down.. But has anyone done any radon studies in his underground home??
A: No one has done studies on radon in my home because my home is so well ventilated. It also has no concrete in it. Radon is produced by the radioactive brreakdown of granite, so I'm told, which comprises much of concrete.
Q: I have just ordered you book, but I'm curious if the ideas can work for North Texas soils. Absolutely no one in Texas has basements except big banks, and home foundations are regularly damaged by expanding and contracting soil.
Excellent question. DISCLAIMER. I HAVE NEVER BUILT IN EXPANSIVE SOILS
SO HAVE NO FIRST HAND EXPERIENCE. THE FOLLOWING IS GUESSTIMATE: I think
the consensus among underground architects is that if you feel you must
go underground in expansive soils excavate a vertical crawl space between
the walls of the structure and the soil. Extend the roof out a couple
of feet over the edge of the excavation. Be sure to allow for the angle
of repose of the soil (the angle at which the soil no longer crumbles
down.) Or build above ground and berm up and over. Insulate the bermed
earth a foot under the surface and you have a heat sink in the winter
and a cold sink in the summer (open windows in the cool of the night
then.) I always advise building a shelter first close to where the house
will later be built so they may be connected. Do your experimenting
and make your mistakes on the shelter. It should have the vertical crawl
space, of course.
I am not a structural engineer and so this is only a guess and it may
be a bad one. I'd take your questions to such an engineer. I suspect
4x4s would work for posts with a light dirt load on the roof but not
for the girders and beams. To lighten the roof load further cut that
foot of earth to six or eight inches and beneath it use some rigid foam
insulation to insulate away from desert extremes. Plywood outgasses
chemicals. Sure you want to use it? Have you tried salvaging lumber?
You should definitely be looking for used windows, too.
Q: I am considering building a large PSP 2+ Story garage/barn into a hillside up in the mountains of Colorado. Our forests up here are increasingly beetle killed and needing to be removed. Do you think that these trees are still structually sound both as poles and as underground siding? (Of course I will be using a waterproofing material prior to backfilling)
A: Sure. Most insect kill is due to their action in the bark. Carpenter ants and termites bore into the lumber part of the tree, but I doubt any beetles do. Drop a tree and do some exploring into the interior and edges of the logs to see where the damage is. But, yeah, I'd encourage you to use the material for PSP. Incidentally I've begun using EPDM for waterproofing on my roofs and am highly impressed. May try it on the sides next.
Q: I am considering building my own home, in the research phase, and am intrigued by your PSP concept. It is very interesting how simple your system is, and I am heartened that others have built such beautiful homes. I have devoured your book and was wondering if your Ridge House was ever completed. Your website as well as your book states it is under construction.
Q: I live in northeast Texas near the City of Clarksville. Our soil is an expanding clay that can be a challenge. Over 20 years ago I started a house project that was, for lack of a better term, a partially sunken underground pole barn. The idea was from a book by an Idahoan named Mike Oehler. It incorporated a dirt floor with plasic sheeting and carpet stretched over it. Really a basic building. The ceiling was large timbers and the walls were wood with plastic behind the wood to seal from the dirt. In trying to construct this dwelling, I used treated (penta) posts and oak timbers. Or at least I thought it was oak; an unscrupulous sawmill operator sold me sweet gum instead of oak, so it rotted before we could do anything. Now I have the site with no timbers and 33 posts standing. The original plan has problems, the cost of large timbers, the plastic sheeting causes moisture behind the wood, resulting in rot. With costs of building so high,
I had considered some type of dirt, cement, and straw type building blocks for the walls. The roof is still up in the air as to what to do to it. If you have any ideas what could be done I would appreciate it. We have got to do a better job with out houses, and it looks like you have done some excellent work that is energy efficient and does not waste our resources like conventional construction.
A (Kelly): For any portions of the house that will be bermed, or underground, I would recommend the use of earthbags or some masronry material, such as stone, lightweight concrete, etc. that will not be vulnerable to rot. The rest of the house could be almost anything, although insulating materials are better, such as strawbales, cordwood, or earthbags filled with crushed volcanic rock.
Q: I am very interested in building a PSP home and will be purchasing Mike Oehler's book. However, I was curious if it is possible to build this type of home in Northern Ontario which is in Canada. Some winters we get a lot of snow, and it can be very cold. My concern would be the weight of snow on the structure as well as how well an underground greenhouse could stand up to a Canadian winter.
Depending on soil conditions it should indeed be worthwhile to build underground and earth shelter greenhouses in Northern Ontario. We had a our winter of '97 here in Northern Idaho had 13 to 18 feet of snow. The national guard was shoveling school roofs (one collapsed anyway) Some garages and barns went down around he county and on my land two car roofs and a thirty year-old milking shed had their roofs collapse. But none ot the six underground structures on my land were injured, and I only shoveled part of one one time. An earth-sheltered greenhouse is exactly what you need for your country. It will triple your growing season, possibly give you a year-round harvest. We'll have a book out on that soon -- "The Earth-sheltered Solar Greenhouse Book." Meanwhile "The $50 & Up Underground House Book" is where you start for underground housing. When you are definitely committed, "The Underground House Workshop and Survival Shelter Seminar" DVDs are a must. undergroundhousing.com, or 800 328-8790 for information.
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