Mark Mills - Beyond Frank Lloyd Wright

By Janey Bennett

Photos by Al Weber

Of the hundreds of architects who spent time in Taliesin, one of the most interesting and under-published is Mark Mills, who has been quietly producing significant projects throughout Northern California for more than forty years.

Mills was born and raised in Jerome, Arizona, the son of a mining engineer. He completed a BS in Architectural Engineering at the University of Colorado. He then moved to Phoenix and worked as a draftsman for the architecture firm of Lescher and Mahoney, which is where he was when the telegram came inviting him to meet with Frank Lloyd Wright.

At the time he interviewed with Wright in 1944, there were only about 20 people at Taliesin. Mills was summoned to Scottsdale to meet Mr. Wright for dinner at an inn on a Saturday night. Mrs. Wright was upstairs dressing for dinner, and Wright was improvising on the keyboard of the lobby's grand piano. An easy conversation followed, during which Wright said "I understand you've been working in an architect's office. You understand I can't pay you anything." Mills answered, "Yes, I understand that. On the other hand I can't pay you anything." The matter was settled.

Mills spent four years at Taliesin , 1944-48. He left with Paolo Soleri and two others. Subsequently, Mills and Soleri were hired by Mrs. Nora Woods to build a small desert dwelling in Cave Creek, Arizona, which Soleri would design. The result was the Dome House. It was the first published project for either of them.

Mills 1
Photo courtesy of Mark Mills

The house consists of two spaces to deal with desert climate conditions: these Mills refers to as "an umbrella area and a griddle area- The sun would come up and warm that thing during the day and then it would retain the heat during the night. Then, in the morning about the time the griddle cooled off, you could go up to the umbrella area and turn it to the sun and the sun would be on you, so you could move from the one envrionment to the other without air conditioning, theoretically. And it worked pretty well."

The budget for the building was very low: the young architects received $300 for the cost of tools and their maintenance: they camped out on the site.

When the dome house was completed, Mills moved to San Francisco and joined the firm of Anshen + Allen, until a friend invited him to come to Carmel to help on a residential addition. That led to work with Miles Bain, who contracted to build Wright's Walker house in Carmel.

During one of his Sunday morning talks, Frank Lloyd Wright discussed seashells as housing produced by God. He said, "You see, there is never a limit. Nothing indicates that the infinite variety could end, so long as [its] principle is inviolate."

Mark Mills has taken these words seriously, and the results of his thoughts of seashells and other forms in nature as sources for shelters can be seen in a number of his structures. His methods of achieving these forms are as varied as the forms themselves: Here are three different methods of creating a concrete roof which Mills used in three projects built between 1969 and 1977.

Thin Shell Vaults

The Fan-Shell Beach house, designed for a family with children, is set into the sand-dune area of Pebble Beach. It is formed of four equal radiating vaults, flanking a larger center vault. The windows at the flared end of each vault embrace a panoramic ocean view, while the contracted inner face of the house encloses an almond-shaped swimming pool.

Mills tries always to design for a frugal use of materials: he designed the four identical smaller vaults in order that their formwork might be re-used for four pours, since the vaults put no horizontal thrust on their walls. The contractor chose to build the entire formwork and do a single pour. But the original intention gives insight into Mills' approach to responsible design.

The built-up formwork was made of 3/8" ply. This was set on top of wooden arches built up from 2" x 12"'s. On top of the ply, he designed a pattern of ribs of douglas fir. These were wider at the top than the bottom, keystone shape, so that when the formwork was pulled away, they remained embedded in the concrete.

Steel reinforcing bars were placed over the ribs. Then concrete was poured to a thickness of 3.5" and hand-trowelled to a smooth surface. On top of that, Urethane foam insulation was applied and then a 4-ply tar-and-gravel waterproof membrane. The under surface of the concrete shell, the finished ceiling, was sandblasted to reveal the aggregate and the wooden strips embedded in it.

The flow of light along the radiating vaults makes this a space at the same time expansive and closed. The wooden strips in the vaults give an energy to all of the spaces and establish a continuity between each room and the shell-form as a whole.

The building has an area of 2200 square feet and was built in 1972 for a cost of $130, 000, not including the pool.


Responding to a client's request for a structure which carried the memories of the traditions of a Greek island, Mills designed this lightweight barrel- and groin-vaulted structure. It clings close to the ground on a fragile coastal cliff above the ocean near Big Sur, never standing more than fourteen feet above grade, and apparently sliding over the edge in one wing. The "transept" of the cruciform structure is 72 feet long, paralleling the edge of the land. The "apse" drops seven feet to create a special space, closer to the sea and removed from the activity level of the house. The window intersections, essentially groin-vaults, form pointed arches which create an atmosphere more Oriental than Gothic.

Gunnited Barrel Vaults

The formwork was constructed of 3/8" plywood, over which steel reinforcing was laid. Because of the cylindrical form, there was no way to pour concrete in place: it was Gunnited onto the formwork. In this house, the insulation was placed inside the shell, and the walls and ceilings were then plastered. The exterior surface was covered with an Elastrometric Roofing System which is 26 mils thick. The final layer of this Neoprene surface was mixed with crushed walnut shells, for texture. This combination was applied on all exterior surfaces.

In 1969, this house cost $75,000 to build. The house covers 1950 square feet.

Beginning from an oculus and tripod arch which define the skeleton of a dome, Mills then hung steel re-bars 16 inches on center from the oculus rim and ribs out to a large concrete perimeter ring somewhat like a floating horizontal hat-brim. The hanging steel drapes itself in a catinary arch, a pure tension system. The perimeter ring is in compression, and holds the steel in an extended position. This is exactly the opposite of a traditional dome built of stone: there the stone blocks in compression are locked into place by a tension ring at the base.

Ferrocement Roof

Steel mesh was placed on top of the re-bar, and then 3/4" thick cement was applied by plasterers. The interior surface was formed by brushing the surface of the cement as it came through the steel mesh. The shape of the re-bar is expressed faintly, adding a directional pattern. The cement contains a pea-gravel aggregate.

Insulation was placed on top of the cement and then an Elastrometric roofing system with walnut shells was used, exactly as in the barrel vault house.

The perimeter walls supporting the roof ring are made of exposed aggregate ribbed block. They move outward 3/4" per course, creating shadows on each of the courses of block, and adding to the sense of dynamic volume inside the house.

To bring light through the compression ring, Mills carved away twelve teardrop-shaped cavities. In plan, these can be seen to be voids within arcs in the circle-based geometry of the roof. The shadowplay of light through the house is one of the delights of the space.

Bathrooms are located at the perimeter of the interior space, so they utilize the compression ring as their ceilings. The rest of the room divisions throughout the house extend only to 6'8" so that the ceiling is experienced as a continuous presence.

This project was designed and built in 1977 at a cost of $346,000 for 2800 square feet of house and 1000 square feet of garage. All three of these structures were constructed by the (now-defunct) contracting firm of Taylor Wheeler from Fresno.

Wright said, "There must have been a sense of God in these little (seashell) forms to produce this infinite beauty of form. Just as there must be slumbering in all of us. There is in us, too, that interior sense of becoming which we call God, working in us all, and which, you will see, has infinite capacity which no human mind can ever encompass and imprison." In all of Mills' houses there is a sense of reverent space, of a space designed in homage to nature, to the laws of structure, to God. That, most of all, is his inheritance from Frank Lloyd Wright.

Mark Mills uses a structural solution as the organizing principal of a house, giving a unity and intensity to his buildings. His projects share these elements:

  • A sense of volume uniting the entire building, frequently expressed in the ceiling structure and visible throughout the house, uninterrupted by interior walls because his interior walls rarely extend above 6' partition height.
  • A perverse habit of inserting a skylight into the most massive and dense part of a roof system.
  • A fascination with building custom structures by pushing ready-made or "off the shelf" elements beyond their intended uses.
  • A willingness to let the dimensions of recycled materials, i.e., used bridge timbers, determine the dimensions of the structure.
  • An impatience with luxurious materials and conspicuous waste together with a respect for the aesthetics of structure.
  • A reluctance to grade the site to accommodate the house. He will make every effort to accommodate the form of the site instead.

Mills demonstrates this last principal in the Copper Spine house on a rocky promontory in the Carmel Highlands. The site is primarily large rubble, with one solitary projection of bedrock in one corner of the house's footprint. In that corner, Mills cushioned the foundation bed with shock-isolating material to more nearly match seismic response to that of the rest of the foundation.

Copper Spine

The arching glulam ridge beam slopes to conform to the slope of the site. The building appears to crouch on the edge of the rock, its shoulders represented by the concrete roof ledge cantilevered in three feet from the perimeter walls which flare out at 11o. 2" x 3" resawn douglas fir strips span the area between the cantilevered ledge and the ridge beam, creating a warped surface. Their edges are not flush but staggered in a wedge as the warp requires. This shift of plane casts rhythmic narrow shadows along the ceiling surface.

The site is exposed to strong surf and winds. Twice in its existence, in extraordinarily stormy seas, sea-foam has washed over the house.

exteriorThe arching ridge beam is pin hinged on its inland end, in a massive buttress of concrete. On the ocean end, it passes through a window and rests on a roller, in order to allow the ridge beam to deflect without forcing its buttress outward. In this way, Mills eliminated the more difficult footing considerations.

The exterior surface of the beam is covered with crimped copper, oxidized green by the sea-air. The windows select and frame the view of the sea. The exterior concrete walls are ribbed and bush-hammered, tinted grey-green to blend with the native planting of sage and succulents. The interior wall surfaces are sandblasted to reveal the granite aggregate.

The house was built in 1966 for $120,000.

The Mills house with the least impact on its site was built in 1970. It hovers in the middle of an untouched pine forest, resting on a cluster of four concrete piers which support two pair of crossing prestressed concrete roof beams, from which the floor is suspended by steel rods. Wooden window mullions encase the rods, which are visible only around the entryporch, where the system is exposed.

Mills was asked to design a vacation home so compact and complete that the clients' married children would be discouraged from suggesting that they add more guestrooms. The client established the floor elevation he wanted by leaning a ladder against a pine tree and climbing to a height of about twelve feet. His other requirement was an unobstructed view of 180 degrees.

Structural Elegance

Mills enjoys turning expectations around: This very custom house is made from elements which, to some degree, have come "off the shelf." The vaults for the roof were pre-formed of 3/8" plywood sandwiching six-inch insulation, the same barrel-vault unit used in the construction of several Safeway stores, the Sausalito Yacht Club, and other commercial and warehouse applications. Steel I-beam forms generally used in fabricating prestressed beams for the highway department were used to fabricate the prestressed beams reinforced in this instance for their cantilevered loads. Metal inserts were cast in the bottom flange of the I-beams. Into these the suspension rods were threaded.

Mills said, "The house could have been done with glulam beams, but they would have been shoulder-high. These prestressed concrete beams are only 3' high. I hung the house below the beams so the client could lie in bed and see where his money went."

The expressed structure is enhanced by careful handling: the I-beams are sandblasted to reveal the small aggregate. The piers are bushhammered around deep cast grooves. The plywood vaults are surfaced on the inside with the same ribbing of douglas fir which was used (and removed) in the concrete piers, reinforcing the sweep of light which travels along each of the axes of vault. Natural light enters the house at all four vault-ends.

The entry-living room axis is one beam-width higher than the bedroom-guestroom axis, which it intersects. A few older pine trees extend above the house, but most of the treetops hover near the floor-level. Beyond them lie Pebble Beach, Carmel Bay and Point Lobos.

This roof is also surfaced with the elastrometric roofing system and crushed walnut shells. At some time during the past 23 years, the roof surface was painted a grey tone similar to the bushhammered piers. This house has been uncommonly lucky in its aging process: Its present owners, working with the architect, have restored it to its original condition, and have furnished and appointed it with sensitivity and restraint. The house is balanced and in full bloom.

The interaction of complex design and simple tools and construction methods remains an important part of Mills' work. His buildings' elegance comes from their aesthetic and structural concepts rather than from expensive materials. He has built more than thirty-five residences throughout California, and his Carmel office continues in full operation. His work honors the process of architecture and offers many lessons to those willing to take the time to track it down and read it.

Originally published in the Journal of the Taliesin Fellows - Issue 10, Spring 1993.