Mountain Architecture: An Alternative Design Proposal
BUILDING IN THE MOUNTAINS
Tremendous variety manifests itself in the mountains. The colors range from the deepest browns of the forest floor to the lavender and pink of an alpine meadow spotted with wildflowers. There is the snow, in brilliant contrast to the dark evergreens or the vivid blue sky, and the Douglas fir, towering over the most fragile fern. The mountains are often resplendent with the contrasts of light, color, and form, but occasionally, such as when clouds are pressed to the ground while dropping a blanket of fresh snow, these contrasts will disappear altogether and turn everything to a misty white. Recognizable surroundings are often obscured; even the ground beneath one's feet can disappear. As the sunniest days are bright, the nights in the forest can be as dark as the deepest cave. Yet the forest will still be alive with the sounds of wind in its branches or the meanderings of an occasional deer.
Mountain regions can be divided into several broadly defined altimetic zones (Figure 1.1). Although the elevations of these zones and their specific characteristics vary from region to region, their general configuration is found consistently throughout the mountainous areas of the world.
Mountain buildings are defined as those which are built in the highest of the three zones. These zones are outlined as follows:
The High Forest: This broad zone begins where the winter snows remain on the ground for a week at a time or more, and continues up to the timber line (the highest elevations where trees grow in numbers). It consists primarily of coniferous trees with scatterings of alder, maple or other deciduous trees, especially at the lower elevations. The texture of the forest varies from majestic stands of old growth conifers to younger sylvan glades of mixed evergreens and vine maple. Open meadows and lakes are plentiful and the summers brings a rich variety of undergrowth which easily survives from year to year.
The Alpine Zone: This zone comprises the region from the timber line up to just below the permanent snow fields. It is generally found only on the shoulders of the tallest peaks, and in the summer is often covered with a multitude of grasses and wildflowers. Small huddles of well-weathered white bark pine or other such hearty trees brave the harsh winter storms. In the Cascades, few buildings are found in this zone except right at the timber line where the trees offer some protection. Broader and more protected in other parts of the world, the alpine zone is commonly scattered with summer houses or covered with expanses of usable pasture land.
The Permanent Snow Zone: This zone covers the tops of the highest peaks, with everlasting snowfields and immense glaciers of moving ice. An occasional climbers' hut will be tucked into the folds of the mountain between the glaciers but otherwise no buildings can withstand the ravages of the harsh climate. Even in the summer the environment at this elevation can turn hostile to man without warning.
These three zones are primarily distinguished by the effects of climate on vegetation. Within any particular region of the world, the specific characteristics of each zone are determined by factors such as the harshness and duration of the winter, the amount of snow accumulation, the intensity of the prevailing winds, and the geomorphic configuration. In addition, seasonal variations can be quite dramatic. As the winter snows recede and disappear, a very different summer landscape is often revealed. Where the ground has been covered by snow for many months, the difference is especially striking. A forest easily traversed on skis in the winter-time may be impenetrable on foot later in the year as the dense undergrowth is exposed.
Weather in the mountains is often hostile and unpredictable. Storms develop seemingly out of nowhere and in a matter of minutes can reduce visibility to practically nothing. Large amounts of snow can fall in a short period of time, altering dramatically the contours of the landscape. Due to the rarified atmosphere and usual lack of airborne pollutants, the direct incident sunlight is much more intense here than at lower elevations. The increase in the amount of damaging ultraviolet light is especially noticeable.
Wind in the mountains can be severe. It piles snow into drifts or deposits it in large amounts on the lee sides of obstructions. Precarious cornices can be formed anywhere the snow is blown over a sharp dropoff, even on buildings. Not uncommonly, the wind will be strong enough to drive rain or snow far up under shingles or through the smallest crack in the siding.
While the form of a snow pack is altered substantially by the wind, snow after it falls is constantly changing. Newly fallen snow is mostly air, but the density increases almost immediately due to gravity or the metamorphosis of the snow crystals. Numerous layers are eventually formed, exhibiting a wide range of characteristics. This is especially true if rain has fallen on the snowpack and is later allowed to freeze.
This dramatic difference between layers is often the cause of avalanches. Although there are many specific conditions under which avalanches occur, their awesome, destructive, power is released primarily due to the ability of one layer to give way and easily slide upon another. Exactly when an avalanche will occur is rarely predictable, but with careful observation and planning its path can be noted and avoided.
Movement in a snowpack is only occasionally seen in the form of the thundering avalanche. As snow is constantly changing, it is also slowly moving. This movement, which is often imperceptible, is termed snow creep. It is caused not by the discrete sliding of one layer upon another, but can be likened to honey sliding off a knife--a highly viscous substance whose movement is restricted where it contacts the knife, yet is free to flow at a faster rate on the surface. A glacier moves this way on a grand scale yet with even small quantities of snow, creep is a force not to be underestimated.
Much of the character of the mountain land suitable for building is derived from the ubiquitous forest. Due in large part to its advanced evolutionary stage of development, the forest, as an ecosystem, exhibits unique characteristics. Complexity, diversity, and stability are the primary attributes common to these older forests. This concept is presented and illustrated by Ian McHarg in a discussion of the contrasts between the sand dune and the primeval forest:
It is interesting to note that under a deep blanket of winter snow, the high forest can, at times, take on the attributes of its opposite, the sand dune. The numbers of species of both animals and plants is apparently reduced as the animals are driven to shelter, the transient birds take their leave, and the undergrowth is all but obscured. The uniformity of the snowpack replaces the teeming diversity of the meadow and can even disguise a frozen lake. But it doesn't take long for the complexity of the forest to show itself again in the calm days after a storm. Resident birds and squirrels appear, as do the rabbits and smaller mammals and rodents. The trees show their individuality and different species become recognizable. Thin spots, swept of snow by the wind will expose some of the undergrowth as the sun's energy is absorbed.
To adequately address the program, function, and purpose of a new structure in the mountains, an attempt should be made to discover why we go to the mountains in the first place. The mountain wilderness is no longer an obstacle in the path of civilization--recreation is the objective. The course of this turnabout is not difficult to chart but the specific attributes which now draw us to the mountains are not as apparent. Throughout history the descriptions of the mountain's essential character has not changed. The mountains have always been presented as wild wilderness: solitary, mysterious, chaotic, and unknown. It is only man's perception of the value of these qualities that has changed. While the northwest Indians, for example, saw the mountain peaks of the Cascades as the dwelling place of the mountain spirit and treading on their flanks brought mortal danger, it took but one climber to dispel this legend and only a few generations for it to become yet another story of the past.
For the most part the mountains are still considered wilderness, or at least the character of the mountains is analogous with the wilderness character. Lengthy discussion has been brought on the value and relationship of wilderness to man without focusing on the mountains per se, but I believe the arguments in this case to hold true for both the specific and the general; therefore the two terms--wilderness and mountains--will be used interchangeably.
The American Heritage Dictionary defines wilderness as "any unsettled, uncultivated region left in its natural condition."(4) It would seem then that a building in the wilderness is a contradiction in terms, but if we accept this definition in its strictest form we must then ask at what point a region ceases to be wilderness because of man's intrusion or whether man can be a part of the wilderness at all. I would prefer to leave the details of these questions to others to debate and assume that the definition will allow the inclusion of man and his architecture; if not in the wilderness, then near enough to it to allow us to discuss the effects of the mountain wilderness on the designs of his structures.
Appreciation for the mountain wilderness has not always been what it is today. It has been molded by centuries of culture. Indeed, the concept of "wilderness" only exists because of civilization, or, as Roderick Nash in Wilderness and the American Mind asserts: "civilization created wilderness."(5) Our separation from the causes and effects of nature millennia ago put us in a position to view nature as unfriendly. But the aesthetic appreciation we enjoy today grew out of a deliberate change of attitude. In western civilization this turnabout was precipitated by the Enlightenment in 17th century England, and, although other cultures may have maintained much closer ties with the natural world throughout their history, the association of man with nature in North America is derived primarily from these concepts. Modern attitudes have stemmed directly from the development of these ideas over the last three hundred years, but the nature of man's antiquarian relationship with the wilderness is also relevant.
Man first saw himself distinct from nature some 15,000 years ago when he left the forests to cultivate the land.(6) The beginnings of agriculture and herding of animals brought a dualism between man-controlled nature and wild nature. The wilderness that he was once part of was now a barrier, a frontier. It was the unknown. Man's myths and legends, contrived partially to explain the mysterious natural phenomenon around him, placed the homes of the gods or super-natural beings beyond this frontier often high in the mountains or deep in the forests. The wilderness was a place of mystical happenings. Until civilization had conquered the wilderness or had in itself grown to the point of excluding it from everyday experience, it would remain the frontier.
This is not to say that man did not venture into the wilderness. Aside from being a source of wild game, the land beyond the frontier provided an avenue of escape for those either forced out of society or discontented with it. The Old Testament relates several events concerning venturing into the wilderness, the most prominent being the flight of the Israelites in search of the Promised Land.(7) The forty years in the desert wilderness not only relieved them of the oppression of the Egyptians but the "wild country came to signify the environment in which to find and draw closer to God. It also acquired meaning as a testing ground where a chosen people were purged, humbled and made ready for the land of promise."(8) Freedom of worship was often a motivation to breach the frontier and set out into the unknown. For the Puritans in 1620 the New World represented such a wilderness. It was not simply freedom from the Anglican Church but an opportunity to create an entirely new way of living that made the hardships of the new land bearable.
Despite the willingness to venture far into the wilderness it was still perceived as a mysterious and undesirable place. Good could be found in the wilds but not until it was brought under control by civilization. Monks and hermits, for example, saw the wilds, in their withdrawal from society, as "the place in which they hoped to ignite the flame that would eventually transform all wilderness into a godly paradise."(9) The wilderness experience had value for man as an alternative to what he did not like about civilization, but it was not until much later that this value was linked to its intrinsic qualities.
Man's place in the universe was never quite as secure as during the Renaissance. Man himself was the center and all else subject to his designs, as evidenced by the French landscape designer, Le Notre, at Vaux-le-Vicompte and Versailles. Nature was clearly intended to be under man's complete control.
The seventeenth century brought the Enlightenment and a new scientific outlook on nature. With a better understanding of astronomy and physics, man was no longer resolutely held at the center. "As scientists revealed a universe that was complex and harmonious, . . . they strengthened the belief that this majestic and marvelous creation had a divine source." The association between God and wild nature was solidly assured. Intellectuals of the time came to look on the wilderness not as Satan's world to be feared and loathed, but a place whose characteristics should be admired and coveted. God's work was increasingly more evident in the wilderness as, in the deists point of view, "spiritual truths emerged most forcefully from the uninhabited landscape whereas in cities or rural countryside man's works were superimposed on those of God." The mountains especially shed their negative connotations, sublimity was the new fitting description. There were also the primitivists who felt that greater association with the wild in deference to civilization would bring out the virtues of the mythical Wild Man of the middle ages: his "strength, ferocity, hardiness, . . . and erotic prowess." The wilderness had not changed but its value in man's eyes was radically different.(10)
The intellectual interpretation of nature fostered a romantic turn in literature and the arts, inspired in large part by Jean Jacques Rousseau, himself a primitivist. In "Julie ou la Nouvelle Heloise" (1761), he "heaped such praise on the sublimity of wilderness scenes in the Alps that it stimulated a generation of artists and writers to adapt the Romantic mode."(11) Later in the century, in his three essays to artists and painters, William Gilpin extolled the virtues of roughness and variety in the landscape as "picturesque" and bid his students avoid representing any scene as uniform, symmetrical or smooth.(12) "Romanticism", as a way of viewing the world, embraced the notions of picturesqueness and the sublime along with the religious perspective of the deists.
North Americans, meanwhile, were struggling with Nature on their own terms. A vast untamed wilderness lay to the west, which was unique in the world. America was different and much of her identity lay in this expansive resource. Pioneers had set out against the frontier, and again Nature was the adversary. But there was great pride in their push west and "by the middle decades of the 19th century wilderness was recognized as a cultural and moral resource and a basis for national self esteem."(13)
But the American wilderness was not being confronted by the pioneers alone. Emerson and Thoreau's Transcendentalism was gaining acceptance among the educated in the east. To him nature was seen neither as the adversary it was to the pioneer, nor simply a romantic wilderness either. A connection was presumed to exist between spiritual truth and the natural world of which man was a part. To illustrate the importance of nature in a person's life, Thoreau began his lecture "Walking", published in the year of his death, with these words:
Later in the same lecture he delivered his now famous lines: "the West of which I speak is but another name for Wild; and what I have been preparing to say is, that in Wildness is the preservation of the World. Every tree sends its fibers forth in search of the Wild. The cities import it at any price." But, "man cannot afford to be a naturalist, to look at Nature directly, but only with the side of his eye. He must look through and beyond her."(15)
The important lesson here was that direct contact with wild nature was not just valuable but essential to moral and spiritual health--not the complete abandonment of civilization but striking a balance between the two; "the natural remedy is to be found in the proportion which the night bears to day, the winter to summer, thought to experience."(16)
By the middle of the 18th century, a renewed appreciation of the wilderness had emerged and its effects were felt throughout society. The Transcendentalist views added yet another dimension to the growing attraction for the wild landscape, but it was not until the domain of these expanses was threatened that our current attitudes began to coalesce. Civilization was expanding and for the first time in history there were calls for preservation. The first National Park, Yellowstone, was designated in 1872 and although originally created to protect its unique "curiosities" from private acquisition and exploitation, its value as wilderness was later celebrated.(17)
The men who championed protection and preservation of the wild environment--John Muir and Frederick Law Olmsted in the 19th century and Aldo Leopold and others in the 20th--basically shared the same conviction: there was intrinsic and essential value for man in the wildness of the natural landscape: it was being thoughtlessly destroyed but worth fighting for. Many shared their views, but not all. A constant struggle developed between those who saw the economic potential in the landscape and those who treasured the wilderness for what it was. The growing industrial society "brought confusion, corruption, and debilitating over abundance" which, together with the already popular affliction for the out of doors, generated what Nash calls a "Wilderness Cult."(18) Numerous outdoor clubs were chartered, from the Appalachian Mountain Club in 1876 to the Boy Scouts of America (1910). In the Northwest, enthusiasts from Portland, eager to attract others to mountain climbing held the first meeting of the Mazamas on the summit of Mount Hood early in the morning of July 19, 1894.
The wilderness experience had been popularized. Appreciation of wild nature was no longer restricted to the educated elite who intellectually understood its sublimity and picturesqueness. People began to understand through first hand experience the value of contact with the wilderness and sought to incorporate it into their lives.
There is no question that now we are going to the mountains in greater numbers than ever before; but what really draws us there? Do we wish to escape an unkind society and run to its antithesis, the wilderness; or is it more positive--a desire to be surrounded by the beauties of nature? For each person, of course, the reasons are different and may vary from day to day, or even hour to hour. An understanding of our current motivations can be drawn successfully from the convictions of our predecessors. Many underlying common points emerged although they each interpreted, in their own way, the value of the wilderness.
The wilderness was seen by most, to some degree, as a balance to civilization--a necessary counterpart to society. Thoreau and the other Transcendentalists, for example, advocated such a balance but cautioned against an excess of either extreme; there existed a proper proportion.
A periodic return from the city to the wilderness was prompted by the disappearance of the American frontier in the 1890s. It was felt that there was a need to maintain the virtues earned through previous pioneering experiences. "As our civilization grows older and more complex", wrote Theodore Roosevelt in 1899, "we need a greater and not a less development of our frontier values." Thirty years later Chief U.S. Forester William Greely described the deteriorating situation: "The frontier has long ceased to be a barrier to civilization", he wrote, "The question now is rather how much of it should be kept to preserve our civilization."(19)
The value of the wilderness was also illustrated by its contrast to civilization. The Pioneer was unable to appreciate the wilderness he was passing through because of the lack of a civilized home for which to return to. Often though, his strength to continue a seemingly endless, hopeless journey would be regained by the knowledge that perseverance would eventually lead him to civilization.
It is sometimes said that we don't appreciate what we have until we are without it. The wilderness can be the source of that appreciation. Upon hearing a train whistle from a solitary wilderness camp, the naturalist writer, Siguard Olson, was at first distressed, but later remarked that "without that lonesome wail and the culture that produced it, many things would not be mine."(20)
Edward Abby, a contemporary critic of many of society's profit making ventures, implies a similar need for balance: "A civilization which destroys what little remains of the wild, the spare, the original, is cutting itself off from its origins and betraying the principle of civilization itself."(21)
In turbulent periods of history, the need for a balance between civilization and wilderness was expressed more radically--in terms of an escape from society. The result was either the formation of a newly structured society, as with the Puritans, or an abandonment of civilization altogether. The monks who "regarded wilderness as having value only for escaping a corrupt society" found sanctuary in the mountains and were content to let civilization go its own way.(22)
As a result of a search for new lifestyles, the 1960s witnessed a frequent desire to escape to the wilderness. Such pronouncements as "I'd rather wake up in the middle of nowhere than in any city on Earth"--Steve McQueen in the popular Sierra Club book On the Loose; or, "I go to the wilderness to kick the man-world out of me"--Colin Fletcher, author of The Complete Walker, were not atypical. But for Fletcher, at least, it was still a matter of balance. "The last thing I want to do is knock champagne and sidewalks and Boeing 707s. Especially champagne. These things distinguish us from other animals."(23)
Implicit in many discussions about the value of the wilderness experience is the resultant improved mental and physical health and well being. This was fully recognized by Frederick Law Olmsted and brought out forcefully in the 1865 preliminary report on Yosemite Valley. To him it was "a scientific fact that the occasional contemplation of natural scenes of an impressive character, particularly if this contemplation occurs with relief from ordinary cares, change of air and change of habits, is favorable to health and vigor of men and especially to health and vigor of their intellect." Further on in the report he concluded his argument, "the enjoyment of scenery employs the mind without fatigue and yet exercises it; tranquilizes it and yet enlivens it; and this through the influence of the mind over the body gives the effect of refreshing rest and reinvigoration to the whole system."(24)
Later in the century, Olmsted's opinions were supported by the conclusions of Sigmund Freud concerning the repressive nature of society and its detrimental effects on the individual. Freud's views were shared by many and for the first time there appeared quantitative descriptions of the essential value of man's continued contact with the natural world. As an example, for the wilderness activist Robert Marshall, the wilderness was, in contrast to the fast-paced complexities of society, a simple place where man was allowed to let himself slow down--where a person could be relieved from "the terrific harm caused by . . . suppressed desires."(25)
Relief from stress is perhaps an obvious benefit of being removed from the city to the wilderness but there is also benefit to be realized by the stress induced by the challenge of the wilderness experience itself. Considerable confidence and self esteem can be generated by relying on the self sufficiency required to overcome the difficulties of travel and survival in the woods. A most striking example is the success of an Oregon State Hospital experiment conducted in 1972, in which fifty-one mental patients were led on a two week wilderness trip. The program was designed to "shake them out of their protective habits of defeat, helplessness and passive compliance." For many of them it did that and more. "Nobody failed." Fourteen patients were later able to be released from the mental facility because of the experiment.(26)
The existence of physical challenge is often outwardly acknowledged as the draw of the mountains today. Climbers and skiers have, from the beginning, found challenges not available in the urban or rural environments. There is always a certain element of danger involved in these chosen activities and not infrequently one's very survival is threatened. The motivation to seek out these experiences comes in part from the relative comfort in which our society allows us to live. One would have to agree with Nash that "one of civilization's supreme ironies concerns the elimination of challenges, including fear, hardship and pain, that merely surviving in the precivilized world entailed."(27)
Beyond the physical challenge, many have spoken of various ways life-giving inspiration is imparted by the mountains. One such person was the Transcendentalist John Muir. In 1898 of this he wrote: The tendency nowadays to wander in the wilderness is delightful to see. Thousands of tired, nerve shaken, over-civilized people are beginning to find out that going to the mountains is going home; that wilderness is a necessity; and that mountain parks and reservations are useful not only as foundations of timber and irrigating rivers but as foundations of life.(28)
Ian McHarg in his influential 1967 book Design With Nature put it similarly:
In a more specific sense a direct correlation was often invoked between the mountain wilderness and divine inspiration or faith in God. The mountains were able to bring one both physically and spiritually closer to God, the Creator. It was no accident that the chosen place for Moses to receive the Ten Commandments was high in Mount Sinai. We are also reminded of the deists and Transcentalists for whom the association of God and nature formed the very foundations of their beliefs. "It seems so self evident," wrote John Muir in his Alaskan Journal, "that one cannot be lonesome where everything is wild and beautiful and busy and steeped with God." Many years later while watching the "light leave the cold shoulders of Mount Rainier," William O. Douglas continued the thought--"it is easy to see the handiwork of the Creator in any meadow. But perhaps it takes these startling views to remind us of His omnipotence."(30)
Nature has the power to remind us of our mortality. A wilderness experience can, and often does, reaffirm the tacit understanding of man's biological union with the natural world: The economy of nature and the ecology of man are inseparable. . . . Man's destiny is tied to nature's destiny and the arrogance of the engineering mind does not change this. Man may be a very peculiar animal but he is still a part of the system of Nature.(31)
Ecology is a relatively new science and the vigor with which we pursue the acquisition of knowledge as to the understandings of the interactions of Man and Nature only underscores its importance. The immediate consequences of the misapplication of our technologies can be catastrophic, and thus our unity with nature has become more humbly evident than ever before.
It can appear that there are as many reasons for going to the mountains as there are people to go there. For some it is a biologic need--rest, relaxation, a change of pace, a new direction, a way out of a rut. For others it may be more spiritual. Inspiration--divine or otherwise--to continue along life's path. But many do not know exactly why they are urged towards the mountains and probably don't care or have a desire to find out. It is simply a place to pursue one of the many outdoor activities found fashionable by today's society--skiing, hiking, climbing, fishing, or just "getting out of the city."
There are distinct, specific needs for the individual which contact with the wilderness can fulfill. The first, and perhaps only need is created by the mere existence of civilization itself: a balance between cultured society and the wild natural environment. For the mountain visitor, there to maintain the balance, the wilderness experience brings improved mental health, the freedom and solitude so necessary for invigoration of the spirit, and an empirical understanding of our unity with nature.
But most importantly therein lies the optimism required by any member of society to bring the positive changes essential for the continued health of civilization. Wendell Berry in his recent book, The Unsettling of America, writes,
He reminds us that "it was the desert, not the temple that gave us the prophets; the colonies, not the motherland, that gave us Adams and Jefferson."(32)
Whether it be a tent or a three-hundred room hotel, a primary purpose of any structure in the mountains is to protect its occupants from the adverse effects of the environment. The weather conditions encountered in the mountains are often much more severe than at lower elevations. As a consequence the designer must anticipate the effects of these natural forces on the building envelope and provide for them accordingly. With sufficient forethought as to how the snow, wind, rain and sun will affect it, a structure will not only be able to respond to its programmatic requirements but be safe to be in and around. Its own well being will also be assured.
Most problems associated with building in the mountains are caused either directly or indirectly by the accumulation of snow. Familiarity with the nature of snow and its processes of transformation will help the designer anticipate snow related problems before they occur.
Snow exists in many forms and is constantly undergoing change. When created in the atmosphere snow exists first as crystals, generally hexagonal in pattern, which have grown around minute dust or ice particles.(33) As it falls, changing air temperatures and vapor conditions manipulate its form causing the crystal to grow into its unique but familiar shape. At temperatures near freezing the snow crystals will form clusters and fall as snowflakes. When the form of the crystal is obscured by water droplets frozen to it (rime deposits) a type of snow called "graupel" results.
Over time the new fallen snow loses its original structure as various forms of "metamorphism" occur. The "crystals tend to approach the uniform conditions of rounded grains . . . and the snow cover becomes more homogeneous." This is, by definition, old snow. The density of the snow pack increases as settlement takes place.(34)
The amount of water in new snow prior to any settlement or melting is usually from around seven to ten percent by volume. Generally the density increases with the air temperature although a lot of variation is found right around the freezing mark. The wind will also pack it as it falls "to form a dense fine-grained snow structure."(35)
As snow plies itself against the walls and roof of a structure, unusual and sometimes unexpected forces are developed. Light snow accumulations produce primarily vertical gravity loads but as the season progresses and snow piles up against the building a combination of both vertical and horizontal loads must be resisted. Characteristically dynamic and evolutionary, the snow pack often shifts the application of this load from one point or surface to another, making precise prediction of the loading configuration difficult.
Although snow falls uniformly from the sky it almost never ends up on a building that way. Wind will deposit most of the newly fallen snow on the lee side of a structure and occasionally build cornices along ridge lines. More often than not, and especially on buildings with steeply pitched roofs, the overall loading of the structure will be quite eccentric. If enough snow accumulates on one side of an inadequately supported building, it can be pushed from its foundation or severely racked. Even flat roofed structures are not immune from this condition. South-facing exposures will also tend to lose their snow before the shaded portions, further accentuating the problems of differential loading. Thus it is important for the designer to consider the prevailing storm-wind directions if the average winter snowfall is heavy.
Once the snow has accumulated on and against a structure other kinds of problems develop. Bridging or "arch" action, a phenomenon not visible from the exterior, will transform a relatively continuous application of force to a series of a few concentrated loads, greatly increasing the stresses on the structure. With few exceptions the snowpack will arch from support to support (bearing wall or column line) rather than from along the midspans. It "is especially apparent in long limber spans under five or more feet of snow." The effect of bridging is not insignificant, therefore the results of snow loads being transferred directly to beam bearing points and column connections should be considered carefully.(36)
Creep is another problem. Snow buildup will always be accompanied by snow movement, however slight, and if this movement is unduly contained, damage will result. Especially susceptible are converging roof valleys, such as between dormers, and contained areas serving a receptacles for large quantities of snow. If the snow deposit pattern is such that these conditions appear, the only remedy other than from alteration of the structure is to remove the snow as it accumulates.
Snow removal next to a building is not only costly and time consuming but can be very dangerous. The 1974 addition to the dining room wing of Timberline Lodge serves as an unfortunate example. "Assistant Ranger Warren Olney said that the new wing had changed the wind patterns, causing the snow to build heavily on the northeast corner. The passageway from the new building to the old was being pushed out of position." Jack Grauer's account in Mount Hood: A Complete History goes on: "Wright Mallery, Supervisor of MHNF announced that the snow had done $300,000 damage to the lodge and the new wing. The main dining room had been damaged and the passageway from it to the new wing had been pushed away. . . . Dick Woodrow of the USFS recreation office commented that $80,000 per year is an average need in maintaining Timberline Lodge." Considering that the cost of the damage was almost one-third the original appropriation this was an expensive design flaw.(37) Since then a snow cat has had to keep the snow level in this area well under control to avoid future damage.
The only sure way to reduce destructive or hazardous snow loading conditions is to know how much snow is expected to fall, where the wind will put it, and to where the snow will eventually move. But even with this knowledge at hand determination of specific snow loading values useful for design is difficult. The density of snow is constantly changing and, as periodically occurs in the Cascades, rain may soon follow a heavy snowfall. Ian Mackinlay in Snow Country Design, does, however, offer the following guidelines:
In addition, it is advisable to treat snow as a dead load rather than a live load. Where the snowfall persists all winter the load duration on the structural members is usually such that full design deflection may be expected.
The guidelines presented in the Uniform Building Code (1982) are minimal at best, and determination of the design snow load is left primarily up to the building official(39) (See Appendix A). The National Building Code of Canada goes into considerably more detail on snow loading, and "is far superior to any code currently (1974) used in the western United States. Much of the code could be adapted to significantly improve the design standards of building" in the western mountains.(40) In the Canadian code the roof snow load is found by applying various snow load coefficients to the ground snow load. The basic load coefficient is 80 percent, and further allowances are made for roof slopes in excess of 30 degrees, non-uniform loads, and wind exposure(41) (See Appendix B).
Earthquakes in snow country are no less common than in the lowlands but there appears to be inconsistent concern for these effects on a heavily snow loaded structure. With a snow load greater than 30 psf, the UBC requires that a minimum of one-quarter of the snow load be included as dead load in earthquake calculations but again leaves the final design load determination up to the judgment of the building official.(42) A similar requirement is made by the Canadian Code but without the minimum load exception.(43) The office of Architecture and Construction for the State of California uses "50 percent of the design snow load, less 10 percent . . . as dead load" which, as a guide, appears to be more reasonable.(44)
Some may argue that a load reduction is appropriate for steeper roofs as they are more likely to shed their snow upon the earthquake's initial impact. Two points seem to counter this: if the snow level around the building is high the snow may not have anywhere to slide to, but remain stacked up on the roof; and more importantly, it is likely that the greatest damage will occur with the initial shock, before any snow has had a chance to slide.(45) All in all, the effects of an earthquake on a structure when fully laden with snow should not be neglected.
Large dripping icicles always seem to add a romantic touch to the scene of a mountain cabin blanketed by snow. But in reality they are usually an indication of a hidden problem known as ice damming. The development of icicles is a first step in the building up of layers of ice at the eaves caused by water seeping from underneath the snow blanket and freezing upon contact with the cold air. As the head of the icicle grows, more and more water is collected behind it. If the resultant ice dam grows too large it will either collapse the eave or force the retained water back through the roofing material and into the building.
In very cold climates where the temperature remains well below freezing throughout the day, building heat is often sufficient to cause the melting required for ice dam formation. The snow blanket itself is a good insulator and will protect the melted water from the cold until it reaches the eave. Under these conditions the initial problem is greatly compounded if the building is heated only intermittently and allowed to cool between uses. Any water which then has been retained behind the ice dam will freeze solid, causing it to grow much more rapidly. Ice at the eave edge has been known to exceed six feet in thickness due to this type of action.(46) Fortunately, ice dams can be virtually eliminated in this type of climate through proper roof design, as will be illustrated later.
When the outside temperature routinely crosses the freezing point, as it does in most parts of the Cascades, some amount of ice damming is unavoidable. Water from snow melted during the day due to warmer air temperatures will often freeze at night affecting a small ice dam. Again, with proper roof design the ice dam can be controlled and damage kept to a minimum.
There are basically three configurations of roof designs in the mountains: the high pitched roof, able to let whatever snow accumulates on it slide off; a lower pitched roof which will retain the snow but let water from rain or snow melt drain to the eaves; and the flat roof, occasionally with a parapet, which must almost always be drained internally. Since two of the most significant functional problems facing the designer with respect to roof design are snow loading and ice damming, the selection of a roof type frequently depends on its ability to handle winter weather conditions particular to the site. Not surprisingly, each configuration has its advantages and disadvantages, but all can function well in the mountain environment.
Flat roofed buildings depend on a reliable waterproof membrane to maintain the integrity of the environmental envelope. Several systems are available which can withstand the expansion and contraction problems produced by the wide temperature swings common to the mountains.(47) By proper application of these membranes, leaks can be virtually eliminated and maintenance costs kept relatively low. Ice damming is still a problem, however, if the roof is drained to the edge of the structure. The easiest solution is to slope the roof in the opposite direction towards an internal drain, which is warmed by either the building's own heat or electric heat tape. Any water collecting beneath the snow will remain above freezing until completely drained from the roof. As long as this technique is used to keep the drain free of ice, dangerous ponding is avoided and ice dams can be eliminated completely.
The potential for excessive snow loading is the primary disadvantage of the flat roof. Wind stripping will usually keep snow levels within predictable range but an unusual heavy storm will occasionally bring more snow than it is practical to design for. Every flat roof will, at some point in its lifetime, need to be shoveled.(48) For this reason they should somewhat restricted in size and not used on buildings subject to only intermittent use.
The ubiquitous buildings in the mountains are those with pitched roofs. Most are designed to shed their snow at on time or another but some, where the overall accumulation is light, retain the snow blanket throughout the winter as insulation. The ability for a roof to shed its snow depends on both slope and roofing material. Metal roofs offer by far the least resistance. Wood shingles and shakes are more reluctant to give up their snow, but it is notable that, in contrast to asphalt shingles, ice will not adhere to them.(49)
Ice damming is a perennial problem with pitched roofs. The easiest and least expensive solution is to provide a heat leak at the lower edge of the roof thereby establishing an increasing temperature gradient toward the eave line. (50) This allows water running under the snow blanket to remain above freezing until it drips free of the roof, eliminating ice build-up and dam formation. If the eaves overhang the exterior wall the soffit must be enclosed to allow the building heat to reach the ends of the rafters. The "heat leak" solution is the most effective in regions such as the Cascades or Sierra Nevadas where the cause of water run-off is not primarily from the building itself but from daytime temperatures rising above freezing. In colder locations the heat leak becomes an unnecessary source of snow melt and may actually cause ice dams.
In environments where the range of air temperatures remains well below freezing throughout the day "cold roof" construction is the preferred solution to the ice damming problem. In this technique a second roof is constructed over the primary insulated roof with an open ventilation space between. The snow is thereby isolated from the heat of the building and snowmelt is eliminated. The only requirement to make this technique work is that the snow and the membrane supporting it remain at the same temperature. A steady draft of cold outside air must always be allowed to move between the heated building envelope and the cold roof. If a "cold roof" is used in a warmer region there still exists the danger that in the absence of a heat leak an ice dam will form anyway. There is no sense in building a second roof over the entire structure if a heat leak will solve the problem as effectively. Any roof configuration can accommodate cold roof construction, from a nearly flat shed roof to a steep gable, as long as the design principles are upheld. Gable roofs do tend to be more expensive, however, as a substantial ridge vent must be built which will not be blocked by snow.
Another significant problem with pitched roofs is snow dumping. Snow sliding even from a low roof can easily kill a person, therefore it is essential that the building configuration be such that the snow is deposited away from normal pedestrian paths. Shed roofs are often preferred for this reason as all of the snow ends up on one side of the building rendering the other three sides available for pedestrian access. In any case building entrances should be located well under cover and kept clear of dumped snow. Vents and chimneys must be located in such a way that they do not interfere with snow movement. Even a small section of snow above a chimney can dislodge it. It is wisest to place any building protuberance which must extend above the roofline at the ridge or a gabled end. Dormers can withstand most snow movement unless very close together and the snowpack on the roof is exceptionally heavy.
A steeply pitched roof offers no practical advantage over a more gentle slope and is usually found to be the least satisfactory solution where the snowfall is heavy. Very steep roofs are readily susceptible to eccentric snow loading and racking, especially if the building is small enough to allow the eaves to be buried by dumped snow. Uneven snow deposition on buildings exposed to wind is also more of a problem with steeper roofs.
By practical measure, a well designed and constructed building with a flat roof building will face fewer problems over its lifetime than those with a pitch. Gravity loads may be higher and of a longer duration, but the elimination of ice dams and snow dumping hazards more than compensates. The chief argument opposing flat roofs in the mountain setting is aesthetic, due in part to the lack of a vernacular prototype (see Chapter V). Buildings with pitched roofs, on the other hand, generally have more room (due to the existence of useable attic space) and are favored aesthetically. Ice damming can be controlled, and if designed carefully, a building with a flat or sloped roof will function satisfactorily in snow country.
Heat generation, distribution and conservation are obvious important factors in maintaining comfort in a mountain building, but the basic principles are no different here than in the flatlands. In a study of a 12,000 square foot ski day-lodge, forced air was found to be superior to the alternative, radiant heat. It was "the only system sufficiently flexible to handle the widely varying requirements of early morning, midday, and late evening." (51) This fluctuation in need is common in alpine buildings if there is significant southern solar exposure. Insolation is intensified by clearer skies and specular reflection off of the ground snow. Significant heat gain can be realized by midday despite low outside air temperatures. In most mountain regions, however, solar insolation cannot be relied upon as a consistent source of heat, and mechanical systems must be used. Fireplaces can also supply some additional heat but are impractical as a primary source except in the smallest buildings.
In addition to insulation normally provided for a building constructed in a low temperature environment, snow can be use effectively to reduce heat loss. "Regardless of how cold it is [outside], the temperature of the roof of a heated building with three feet of snow on top will remain at 32F."(52)
As snow is an excellent insulator, it is often retained on low slope roofs for that purpose. Compact massing and the use of air locks at heavily use entrances are also very effective in reducing heat loss.
CHAPTER I NOTES
1. Mario Cereghini, Building in the Mountains, (1957). p. 10.
2. Ian McHarg, Design With Nature, (1969), pp. 118-20.
3. Anne Frank, The Diary of a Young Girl, (1952), p. 172.
4. American Heritage Dictionary of the English Language, (1976).
5. Roderick Nash, Wilderness and the American Mind, 3rd ed., (1982), p. xiii. The structure of much of what follows is based on this work. It is an excellent compendium of the history of ideas and events concerning the wilderness.
7. Others include the sending of the goat for Azazel into the wilderness as the scapegoat (Leviticus 16:10), and Adam and Eve's first step from Eden into what could be described as a wilderness (Genesis 3:17).
8. Nash, p. 16.
9. Ibid, p. 18.
10. Ibid, pp. 45-48.
11. Ibid, p. 49.
12. William Gilpin, Three Essays: on Picturesque Beauty; on Picturesque Travel; and on Sketching Landscape: with a Poem on Landscape Painting, 3rd ed., (1808), pp. 8-20.
13. Nash, p. 67.
14. Henry David Thoreau, Walking, The Harvard Classics, Essays English and American No. 28, (1910), p. 407.
15. Ibid, p. 421; Thoreau, Journals, Torrey and Allen, eds., (1906), Vol. 5, p. 45.
16. Thoreau, Walking, p. 411
17. Nash, pp. 108, 113-115.
18. Ibid, p. 144.
19. Theodore Roosevelt as quoted in Nash, p. 150. William Greely, "What Shall We Do with Our Mountains?" Sunset, (Dec. 1927), p. 15.
20. Siguard Olson, Listening Point, (1958), pp. 150-53.
21. Edward Abbey, Desert Solitaire: A Season in the Wilderness, (1968), p. 192.
22. Nash, p. 18.
23. Steve McQueen, as quoted in Terry and Renny Russell, On the Loose, San Francisco, (1968), p. 20; Susan Sands, "Backpacking: 'I Go to Kick the Man-World Out of Me'," The New York Times, (May 9, 1971), p. 7; Colin Fletcher, The Complete Walker, (1970), p. 9.
24. F. L. Olmsted, "Yosemite Valley and the Mariposa Big Trees, A Preliminary Report, 1865." p. 17; p. 21.
25. Robert Marshall, as quoted in Nash, p. 202.
26. "Roughing It Back Toward Sanity," Life Magazine, (Oct. 29, 1972 ). pp. 61, 69.
27. Nash, p. 267.
28. John Muir, "The Wild Parks and the Forest Reservations of the West," Atlantic Monthly, (1898), p. 15.
29. Ian McHarg, Design With Nature, p. 19.
30. John Muir, as quoted in Nash, p. 319; William O. Douglas, Of Men and Mountains, (1981), p. 69.
31. Marston Bates, The Forest and the Sea, (1960). p. 247.
32. Wendell Berry, The Unsettling of America, (1977). p. 174.
33. Ed Peters, ed., Mountaineering - Freedom of the Hills, p. 490. Herein is an excellent and detailed description of the process of snow.
34. Ibid, pp. 490-93. Destructive and constructive metamorphosis are more precise descriptions of the process of settlement.
35. Ibid, p. 490.
36. Ian Mackinlay and W. E. Willis, Snow Country Design, (1965), p. 3.
37. Jack Grauer, Mount Hood: A Complete History, pp. 75-6.
38. Mackinlay, p. 2.
39. International Conference of Building Officials, (ICBO), Uniform Building Code (UBC), 1982 edition, pp. 127,143; Ch. 2305(c). (Hereafter cited as UBC).
40. Mackinlay, p. 7. The Structural Engineers Associations of Oregon and Washington do each publish a snow load analysis guide which relies heavily on the Canadian code.
41. Associate Committee on the National Building Code, National Building Code of Canada, 1980, pp. 144-45.
42. UBC, (1982), p. 133, Ch. 2312(c).
43. Associate Committee on the National Building Code, National Building Code Of Canada, 1980, Subsection 184.108.40.206.(2), p. 148.
44. Mackinlay, p. 10.
46. Ibid, p. 6.
47. Ibid, pp. 21-23. Mackinlay discusses in detail two such systems.
48. Ibid, p. 24.
50. Ibid, p. 23. "The authors [Mackinlay and Willis] consider the increasing thermal gradient towards the eave line caused by the natural design of the roof to be an invention of [their] office and the best solution."
51. Ian Mackinlay, "Linear Plan - California Style," (1967), p. 147.
52. Ibid, p. 146.
Master of Architecture Thesis