There are a couple of structural aspects to Fallingwater that aren't
immediately obvious. The cantilevers are dramatic; there's no question
about that, but much of the drama is actually sleight of hand.
In hindsight, it could have used more structure than illusion, but I still
think some of the ways Frank Lloyd Wright Wright concealed the structure
are pretty clever.
First, below the lowest terrace there are four piers, which carry much of
the weight of the first floor. Even these corbel out from the hillside,
so that they reach out over the stream rather than stand vertically in it.
terraces look as if they're open boxes made of concrete; you don't see
any beams under them. But actually, the beams are within them. The
concrete structure is like the egg-crate or double-T structure of a
modern parking garage, except that it's upside down, so that the terraces
have flat undersides. Wright then laid redwood boards to span the space
between the beams, and the flagstone floor is on top of that.
We're so used to thinking of post -> beam -> floor when we look at a
that it's natural to assume that if we don't see any beams from the underside,
there aren't any beams. It's a natural assumption that there are these
concrete trays, and the next day some masons came in and spread some mortar on
the bottom of them and laid the flagstones, but that's just an illusion.
Another illusion that Wright used was to make some of the window mullions
structural. All of the outer walls in the living
room are windows; there are no corner posts. It's breathtaking, and you
hardly notice that a couple of the window mullions are structural steel,
because there's no difference in material, it's always glass, metal,
glass, metal, glass, metal, glass.
Those mullions transfer the load to the (hidden, inverted) beams on the
lower terrace, which transfer the load to the piers down at the stream
So the upper terrace just seems to fly out from nowhere; it's supported by a
glass wall that in itself is part of a terrace that has most of its structure
hidden in the first place. For a last bit of sleight of hand, Wright threw
out a couple more horizontal planes that don't support anything at all; they
just extend the horizontal lines at little structural cost while adding to
the impression of a building that just flings itself out over the waterfall
with no visible means of support.
From the beginning people said that Fallingwater would collapse; that it was
not structurally sound. Wright meant for it to look like an
impossible structure in the first place. If it was as flimsy and airy as it
looks, it would have fallen down before it was finished. I'm impressed that
the structure is so cleverly disguised, and if they have to spend a few
million dollars after sixty years to drill in some steel that should have been
there in the first place, so be it.
In spite of the fact that this remedial work is necessary, the ways that
Frank Lloyd Wright Wright concealed the structure on this house are
remarkably clever. Half
engineering, and half sleight of hand. And the house still looks like it's
flying, after 65 years.