Although earth sheltering has been around since humanity decided to cover up or dig in to avoid daily and seasonal variations, going underground has lately been revamped with the coming of new materials and excavation ease. After the basic cave dwellings most designs were recessed which was fair for those days and was the easiest way to do it. Hand digging soft rock in cliffs is what we mostly see in old countries but, unless being built in a very dry climate surrounding, the warm humid air coming to the inside would condense on the cold rock walls creating damp living spaces. More ventilation would only exacerbate the problem thus making such dwellings unpleasant. Modern earth sheltering construction eliminates this key problem with suitable insulation and water-proofing materials.
The design should depend on your site's status, topographical
surroundings, environmental year-round weather, budget, personal
involvement, etc... No "one design fits all" here.
First of all is to have an idea of bearing capacities of your soil,
sometimes it is predictable visibly and local excavation contractors are
a good source of info but in 'not so sure' situation get a professional
study of your soils at the required depth. All your project will sit
on this soil analysis, it could even advise you of potential
differential settlement and slope stability.
In its simplest it could go down to; Dig - Build - Bury.
An easy way is to build with concrete blocks, adding reinforcing bars and surface bonding, it is as basic as it can get, plenty of documentation on the net and will leave it to your own investigation.
For those with a bigger project; the poured reinforced concrete has proven it's worth and in some aspects its weakness might need pre-production prospects with its expanding costs to the commercial or industrial level.
For DIYers, novices to construction and those on a tighter budget, I suggest the cordwood wall technique which is relatively easy and if you have time, quite cheap. Properly designed a 10 meters diameter curved wall makes a light, strong retaining and loading wall mostly if you load it to compress the wall and guess what; earth is heavy. Round walls gets you on an arch algorithm that can beat efficiently lateral pressures and avoids complicated corners. Unlike other techniques this wall is your final touch-up, no need for plaster or gyprock ! It is acoustically great due to open pores of wood fiber alignment eliminating cavernous sounds and it offers a unique look which would cost a fortune at your local rustic home designer.
Many other approaches are possible with steel culverts, reinforced ferro-cement, domes...as long as you stay away from wacky $500 underground houses or stacking old tires filled with earth which requires a huge amount of effort with upcoming problems of settlement unless you have a top-notch quality control on it. Ecolo housing for masos or with a lot of free manpower.
Anecdote about the fireproofness of cordwood wall is that a nearby mechanics garage burnt down some decades ago, roof and all collapsed except the cordwood wall that got calcinated on the interior surface and thus blocking the oxygen, so it didn't burn down, they sandblasted it and rebuilt a new roof !
In new suburb developments it would be favorable to group 6 to 12 houses around an inner communal green space and share geo-thermal, solar or other expensive installations and maintenance fees. Different designs are possible for all kinds of surroundings be it flat, hilly, steep, rocky.... more than we might think at first. Earth sheltering pros and cons might go like this:
PROS
- Unique aesthetics.
- Cool in summer, warm in winter.
- Maintenance free unless you want to mow it.
- Great integration to the immediate environment.
- All around comfort and more temperate year-round.
- Will never be subdued to fashion dictates and their costly renovations.
- All covered walls and roof are tornado / windproof, fireproof and noiseless.
- Burglar resistant; fewer points of entry for crooks, makes their loot bizarre.
- Initial structural overcost quickly recovered with energy savings.
CONS
- Harder to get to a problem, if there is one.
- Municipal (f) laws are restrictive and often archaic.
- Will not fit in the insurance homogenized brackets.
- Unlike post and beams structures you'll be bound to weather until roof is up.
- Structural materials at a greater cost (here attenuated by cheap cordwood walls).
- Aesthetically poor between bungalows...
- Not suitable below ground water table (although possible) or on permafrost.
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First troglo
First official Viking settlement in America (rebuild)
From old quarry to home
Total integration
A grouped approach
Back is wind / cold protected.