Right here, before going any further, we will eliminate what, for lack of a better name, I call the First-Thought House. I call it this because it is the design that 99 per cent of the people think of first when considering an underground house on a hillside. It is the design that I considered first myself. Fortunately, there was a six month wait between my decision to go underground and the actual start of construction and in the interim I was able to think my way clear.
The First-Thought House is an attempt to get a view downhill at the expense of the primary consideration, drainage. Drainage, in fact, is sometimes never considered at all. The design consists of a large wall of windows on the downhill side and a shed roof which drains back against the hillside. A cutaway view of the First-Thought House looks like this:
There are five problems which the First-Thought House creates. First of all, since there are no windows on the uphill side, there is no way to achieve a balance of light. Everything facing the downhill windows will be bright and everything facing that blank back wall will be dark and shadowy. Having the windows all on one side creates a second problem in trying to get cross ventilation. To get a breeze through the house with this design a guy would pretty near have to build air scoops (like the funnels on ships). But why? Wouldn't it be better to put some windows on that uphill side?
A third potentially serious problem is created because the entrances must all be on the same side of the house. This is dangerous. In case of fire, cave-in, or attack you are trapped. Few burrowing animals are satisfied with one entrance. It is an instinctive thing with them and it will be with you, too. You just won't feel right with all of the entrances on one side of the house. Your building inspector probably will not feel right either.
Having an exit on the opposite side can save your life as it may have done with yr. author on one of several occasions when bears broke into his house.
A fourth difficulty which is created by the First-Thought design is that it makes no allowance for lateral thrust, a problem which is aggravated by hillsides and/or wet earth. Lateral thrust is the pressure which is exerted against the walls of an underground house. (Some soils exert more than others. Sand is bad, loose gravel is worse, and oozy clay exerts the most pressure of all.) Hillsides move. They creep like glaciers. Woe to the guy who designs while ignoring this factor. In a few years your house may be literally bent out of shape. The walls may be pushed in. By putting windows and a patio on the uphill side as in the Basic Design discussed below, the effects of lateral thrust and hillside creep are lessened and in some cases completely eliminated.
The final, and perhaps greatest, mistake of the First-Thought design is one of drainage. What happens to the water coming down the hill? In most cases no provision is made to take care of it. What happens to the precipitation which falls on the roof? It flows back to join the water coming down the hill. All of that water is going to gang up on you against the back wall. Sooner or later, one way or another, that water is going to find its way through or under the wall no matter what water proofing techniques you use. I have seen it happen. I have seen it happen to very expensive underground structures.
I won't deny that you can get an excellent view with the First-Thought design. And it is a temptation in this, the dawning of the age of solar energy, to face all of those windows to the south to make maximum use of the sun. HOWEVER, those same effects can be achieved by other means without the problems encountered with this design. To reiterate, this design causes five heavy problems. These are: (1) No balance of light; (2) No cross-ventilation; (3) Entrances are all on one side of the house creating a potential trap; (4) No allowance for lateral thrust and hillside creep; and (5) Anticipated disastrous drainage problems.
Was this article helpful?