Subterranean homes face a number of water control problems. Each source of water,
each place where water is likely to show up, has its own characteristics that must be
addressed if all water problems are to be solved. Not all moisture problems are caused by
an excess of water either. Sometimes things may be too dry. This is also a water problem
since we want to keep some things moist and other things dry. Thus all the water should
be controlled.

The sources of water control problems include:

1. Rain water.
2. Stagnant surface water.
3. Running surface water.
4. Subsurface water on the roof (earth sheltered home).
5. Water flowing over the home (earth sheltered home).
6. Water flowing through the earth around the home.
7. Water in the drainage system.
8. Natural ground water, the aquifer, the water table.
9. Moisture in the soil.
10. Indoor moisture producers: bathrooms, kitchens, hot tubs.
11. Plumbing.

Uncontrolled water can cause these major problems:

1. Erosion.
2. Desert or swamp-like surface conditions.
3. Structural failure.
4. Waterproofing failure, dampness, dripping, or flowing water inside the home.
5. Clogging of underground drainage systems.
6. Mold, mildew and insect invasion.
7. Flooding and drains that back up.
8. Overly dry or overly humid interiors.
9. Loss of stored heat and failure to achieve annual heat storage.

So, practical water control cannot be handled by mere waterproofing alone, but only by
a comprehensive water control program.

Keeping the Surface Water Away

 

 

 

 

 

 

 

The most common source of H2O, is the sky. Since it is still popular to build
underground homes on hills, and hills are great water catchers, they have a real affinity for
funneling all that rain water right down on top of that lovely building site you’ve selected. Would you like to have a WHOLE MOUNTAIN of water pour over your home? Yet, that’s
exactly what some of them have especially when the snow melts in the spring.

So, avoid this problem from the very beginning. When you pick out that beautiful spot,
and you take all your relatives to where they are sure you’ve planned your “hermit’s cave,”
don’t take them there on some sunny sunday afternoon. Take them there IN THE RAIN!
Then, while they are laughing and pointing their fingers at the rushing torrent that’s
inundating your preciously picked place…TAKE NOTE! A little adjustment in the
prospective position may preclude a big bill for “excavational earth reorganization.” Don’t
plan so that you have to move a mountain. It’s far easier to move the plan.

The land that is to be moved around should be sculptured to facilitate the easy runoff
of rain water which falls on the roof, and to prevent water that gathers elsewhere from
running onto the home, INCLUDING ITS HEAT STORAGE MASS. Always encourage the
water to move AWAY from the home. This is done naturally by any good excavator. But
other items he can’t change such as the elevation of the house with respect to the land, the
location and shape of driveways, entryways, window wells and the like can back up tons
of water in some of the least desirable places, so these must be planned carefully. But
don’t use the word “sculptured.” Excavators charge more for “sculpturing” than for
“sloping.”

What if you’re stuck with a big collecting bowl like a patio or something, and you have
to do something with all that water? Outdoor floor drains are very popular, and often quite
sensible if installed properly. But, all to often they are put at the bottom of a staircase,
ramp, driveway or other outdoor water collector with the lowest part right smack against the
house.

Have you ever seen such a drain that worked? Aren’t they generally all clogged up with
leaves, dead grass, old plastic sacks, and cigarette packages? If you are forced to use
them, and use them only when you are FORCED TO; take positive steps to prevent them
from being clogged up. A drain cap with large holes will help reduce clogging, but not with
holes so large that they allow the pipe itself to clog. Make sure that the drain entrances are
located in the spot where the water is actually going to be, especially after the concrete and
the earth beneath it have settled. This collection place must be deep and wide enough so
that the water doesn’t back up under the door or even the insulation/ watershed umbrella
before it has time to drain away.

One should watch carefully what he hooks these storm drains to. Sumps are popular
but if they are in a soil that doesn’t drain too well they probably aren’t going to drain any
better through a small sump. So one will probably have to make the drain-pit much bigger
to give the water that is collected more time to soak into the soil. If you use a sump, make
sure you can open it up to clean it. Silt can very easily clog a whole sump, even a big one!

Never connect a storm drain to a septic tank or a city sewer. A friend of mine had a
indoor drain on the floor of his basement (about the same level where it probably would
have been had it been an underground house.) This floor drain was connected, along with
the rest of his home’s plumbing, to the city sewer system that also had storm drains
connected to it rather than to the city storm-sewer system as they should have been. During spring run-off the sewer was very nearly full so it wouldn’t take even the normal
amount of waste water. So, through the floor drain, every time they did the laundry, the
Tide would come in.

How much better it would be if one could avoid catch basins altogether, or at least use
a large storm drain even if it just goes around the house. If you do, you must keep all
drainage sumps and pipes out of the heat storage zone, otherwise they will become
unwanted earth tubes extracting heat just as if all this water were loose and flowing around.

Solving Ponding Problems

Ponding problems occur whenever there is an accumulation of water in an unwanted
place. The most familiar ponding problem shows up in the earth cover on top of a flat
roofed underground home. Ponding has been a severe problem in some homes because
most subterraneans have flat roofs. Flat things are not very efficient at holding massive
amounts of earth–especially heavy, wet earth. A large accumulation of water can actually
cause a structural failure.

Water collects in the center of a flat roof. The roof, due to the increased weight, sags
ever-so-slightly. The puddle gets bigger. The roof bends ever-so-slightly. The puddle
becomes a pond. The roof flexes ever-so-slightly more. The pond becomes a lake. Then
all of a sudden the lake goes away, to become an indoor pool!

You wouldn’t build a perfectly flat above-ground roof, why build one below ground? If
you do use a flat roof, set it at an angle so the water can run off of it, just as you would
above ground. However curved roofs like domes, culverts, and other shell structures work
much better, not only because they can be made stronger, and require a lot less materials,
but because they shed the water rather than allow it to accumulate.

If however, you design for a small storage zone on the roof, as well as a moderation
zone (by including some earth between the insulation and the roof,) potential ponding
problems can be prevented by using the insulation/watershed umbrella because it
encourages the water to drain safely away.

Roof ponding is not the most serious water control problem now, mainly because so
many fine texts have brought it to the fore. However, another sort of ponding has not been
dealt with to such an extent. This is the kind of problem that is all to often designed into
some homes, ponding that usually gathers less water, but occurs in sensitive, hard to deal
with places.

Surface ponds or flowing streams of water can cause difficulties at those places where
a portion of the home must protrude through the earth. The intersection of earth, flashing,
waterproofing, and building can be hard enough to handle, without collecting water on the
roof and then directing it right smack into these sensitive areas. Unfortunately, the earth
tends to angle down toward these delicate places, because we like to have lots of earth
cover that tapers off at the front of the roof. Retaining walls are especially famous for this.
They can easily form a water control problem that can be handled easily by simply directing
Figure 15 Backfill should be sloped so that water will not run right up against anything that must
protrude from the earth cover, and especially those places where the insulation/watershed umbrella must
come near or through the surface.
the run-off some place else.

A good retaining wall has “weep” holes at its base so that water will not build up behind
it, and as often happens, bring down even the biggest ones. Selective, controlled, run-off
will reduce this amount to a trickle, and will prevent water from backing up along the
retaining walls into the house. To accomplish this, we must keep the water flowing on top
of the umbrella a little ways back from the top of the wall, and not right against it where the
collected run-off could seep down between the umbrella and the wall.

 

 

 

 

 

 

 

 

 

 

 

 

Surface water, collected into little streams on top of an earth shelter can eat away the
carefully placed earth cover to expose the insulation leaving a gaping crevasse at the
corners of the roof and down behind the retaining walls. Erosion is sneaky. It is slow but
relentless. We can try to keep the velocity of the water to a reasonable level, but all such
collection streams should be lined with a good stone or gravel base. Such stream beds will
be a very functional part of the landscaping. But the best way to prevent erosion and
control the surface water, in addition to proper sloping and direction is with green plants.

 

 

 

 

 

 

 

The Green Solution to Drainage Problems

Earth sheltered homes CAN be more beautiful than any above ground home. Do I say
that just because of personal taste? No. The primary decoration of a properly designed
underground home is green vegetation. Well laid out landscaping is composed of natural
things: trees, bushes, grass, rocks, flowers, vines and shrubbery of all types. Drive down
a quiet street, the most beautiful one in any town. What is it that makes it beautiful? Isn’t
it the huge trees hanging like decorated arches over the street, the well manicured lawns,
and the great variety of shrubs and flowers that make such a place so much more desirable
to live in? Even in the older sections of town, where the homes are beginning to look a little
shabby, isn’t it the landscaping that has remained beautiful long after the luster of new
construction has worn off? Who wouldn’t want to have a park-like home in his
neighborhood, one with the most beautiful of decorations as its major feature?

However…ten hours behind a growling grass gobbler is not my idea of a “pleasant
weekend at home!” There is no reason why all that newly found green space has to be laid
out like a golf course, unless you golf a lot. Now, you certainly don’t have to mow bushes,
and the slightly longer growing season on the roof makes it a fine place for a vegetable
garden. Remember though, to keep the moderation zone deep enough to save your
insulation umbrella from your shovel! But even if you do have to use a lot of grass,
remember, a well designed earth shelter needn’t have any maintenance that can’t be done
by a sheep!

 

 

 

 

 

 

 

 

A marvelous variety of plant life is available from little tiny seeds, but before you select
your favorites, you should take into consideration:

1. The root system.
2. The amount of water and sunlight that each needs.
3. The climate and the new longer growing season on top of the storage zone.
4. The weight.
5. The usefulness for control of erosion, animals and people.
6. The beauty of each.
7. Their positions relative to each other and the home.

Many conventional earth sheltered homes are deserts up on top, the “brown spot” on
a green hill, because the roof with its thin waterproofing protection must be drained
completely dry. The insulation/watershed umbrella will keep the home and the earth near
it dry, but the moderation zone on top should be made with a high humus soil which will
retain just the right amount of water for good plant growth. The earth cover on the roof
should NOT be drained dry, but the umbrella’s interior should.

Trees and some deep-rooted bushes should be avoided because the engineering may
not allow for the extra weight, and we want to confine the roots to the two-foot-deep
moderation zone. The plastic insulation umbrella will tend to localize roots in the
moderation zone, while preventing them from growing into the umbrella, because it is dry
both in and under it, and roots follow moisture.

So, you can landscape a subterranean home as if you were painting a picture. Just use
your imagination and those natural tools…green plants.

Solving Multiple Problems With the
Insulation/Watershed Umbrella

If you look out toward the Geodome  you’ll see that
it is a green spot on a brown hill. The reason is that it has an insulation/watershed
umbrella. Five moisture sensors were placed in the earth around this building. The top one
in the upper earth-layer, the moderation zone, has been moist since the first rain storm
after construction. The earth there is about two feet deep to allow room for good plant
growth. Under the umbrella it is bone dry, or nearly so, all the way down to the footings.
The home’s entire earth environment is dry in spite of the clay hill in which it is buried,
where the water comes down in sheets during spring run-off.

The proper level of moisture in the moderation zone can be controlled by placing the
insulation/watershed umbrella between that which we want to be moist, (the top layer of
earth called the moderation zone) and that which we want to be dry, (the storage zone, and
the home in it.) This plastic barrier will solve our dilemma by separating these two major
water-related earth functions:

First: Keeping the EARTH around the home DRY makes waterproofing very easy,
eliminates ponding, and prevents transportive heat flow from robbing our heat storage bin.
Also, dry earth has a higher R-value which reduces heat loss out the end of the umbrella,
while allowing the establishment of a permanent warm storage zone.

Second: The moist earth on top insures a well functioning moderation zone, prevents
erosion and fire, reduces the amount of watering needed, and keeps the roof beautifully
green.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Underground Water Control

Pick up any text on underground houses, and you’ll find the same pictures of
subterranean walls with footing-level drain tile, loads of expensive waterproofing…and a
river of water drenching the house. (I suspect they were first drawn by waterproofing
salesmen.) Water flow problems persist. Conflicting claims by the waterproofing industry
haven’t helped much in solving the water troubles, and rapidly rising waterproofing costs
have made earth sheltering even more difficult, and costly. Just lately we’ve seen a
number of pictures in magazine articles, that show a second drain tile near the TOP of the
wall to reduce water flow, both for thermal and waterproofing reasons. That is a little better,
but still far from ideal.

Look closely at the picture below. Note that there is NO drain tile around the perimeter of the
insulation/watershed umbrella, but there is a layer of gravel. Drain tiles remove water much
faster than gravel, too fast for keeping the proper moisture content in most soils. By using
gravel, the excess is drained away, while the moderation zone will retain just enough water
to make those “deserts” blossom.

 

 

 

 

 

 

 

 

 

 

 

The SHAPE of the umbrella is also important. It is round, and like a fireman’s hat, it’s
designed to make the water run off of it. Why else would it be called it an “umbrella?”
Generally, people do not always equate the way things work above ground and the way
they work below ground. But, despite the difference in position, materials, and installation
sequence, the principles of operation are the same. The water will run off the underground
umbrella just like it does off the roof of an above-ground home.

Use Plastic Underground

The best construction material for use in underground water control is PLASTIC. No
one I know personally, would screw in a light bulb by turning the ladder because every
product has its preferred method of application, and its individual attributes. Yet people
persist in installing plastic improperly even showing it installed wrong in many
how-to-do-it-books. Then they belittle it for the problems that result (or they think result.)
While it is bad-mouthed by the waterproofing salesmen, they generally, when all is said and
done, recommend that at least one layer of it be put over the top of their super-good
product!

Polyethylene sheet plastic, often called “Visquine,” is generally used in very large sheets
(20′ x 100′) (6 x 30 m) and .006 inch (0.15 mm) thick. This thickness is usually chosen
because it is the thickest, and toughest of the garden variety plastic you can get for a very
reasonable cost. It has some fine attributes:

1. It is the least expensive of any commercial water-control material.
2. It is not biodegradable and will last a long time.
3. It is fairly slippery.
4. Almost nothing will stick to it, even glue.
5. It is a complete water and vapor barrier.
6. It comes in very large pieces.
7. Water will not only drain off the top of it, but will run under it too.

It also has some drawbacks that require the installer to be cautious.

1. It can be punctured quite easily.
2. It cannot be stretched, and will hold no weight.

1. Sunlight. The ultraviolet light from the sun will eventually turn it to powder. If stored
out in the open for a long period of time it will deteriorate and not work as well when it is
used. Now, the sun doesn’t shine underground, so, only where the plastic has to protrude
above the surface must it be protected with flashing.

2. Burrowing animals. If you live in an area where there are a lot of ground squirrels or
gophers, don’t put out a trap line. Remember, that they were smart enough to live
underground long before you discovered subterranean living. But they don’t have any
plastic to control the underground water for their homes, so they like to dig where it’s
already dry. Ah ha! If you keep the roof of your home moist, as suggested, then they will
move out to become your neighbors, rather than pests. If you plan your landscaping to
match the arid climate that you already live in, and would like it to blend in with the scenery,
protect the umbrella with lots of big rocks. The little fellows are tough, but usually not that
tough. Now, it is true that muskrats and beavers burrow too…but if you have trouble with
these, I’d suggest that you have a big enough water problem to warrant building elsewhere.

3. Frost. Frost will destroy it. When plastic gets cold, it gets brittle. When it moves it
breaks. If it moves a lot, it breaks up in little pieces. Frost is accompanied by both low
temperatures and movement. Of course, the purpose of the insulation in the “insulation
umbrella” is to keep the earth beneath it at a higher temperature than the earth above it.
With the storage mass at about 70E (21E C.) some heat will pass through the insulation into
the moderation zone. This accounts for the longer growing season up there. It also
prevents freezing close to the umbrella. Also, the formation of frost requires the presence
of water, and as we shall see, the entire umbrella will be so well drained that it itself will be
dry. If you are in an area of extreme cold, like the Yukon, a small layer of round river gravel
placed on top of the umbrella should keep that earth somewhat dryer. So a balance must
be found between the requirements for drainage and for water retention based on the site’s
prerequisites.

4. People who like to dig holes on their roofs. So keep the dirt on top of the umbrella
deep enough.

5. People, by improper installation or by stomping it full of holes!

To expect plastic to do a job that it was not designed to do is unwise, like the lightbulb
and the ladder. In all but a few of the examples I have seen, the plastic has been
INSTALLED IMPROPERLY. So, proper installation is vital if we expect it to do the job for
us.