How the Cave House in Kula Kai Came to be Built of Steel home page


Over a lifetime, natural calamities will happen, people will make mistakes, bad people will do malicious things, and termites will continue eating all the wood they can find and making more termites. Most people prefer not to think much about these things. An unpleasant event that is unlikely to happen in the immediate future can be rationalized as something that happens to other people. Denial can provide a comfortable justification for not planning to address these events, and instead take a traditional and easiest course of action. Traditional house construction in the United States means building a wood frame house.


The harm caused by natural disasters such as forest fires, earthquakes, tsunamis, hurricanes, floods, tornadoes has been much greater than it would have been if people gave these things some consideration before building a house or other structure.  Cultural and political factors are also important in determining a building type and location.


Houses can last many years, and barring an unfortunate event or circumstances leading to an alternative use for the land upon which the house is built, it is plausible that a house could stand for centuries if it is properly designed and built.


The decision making process in determining how we selected the manufacturer, Kodiak Steel House, and chose the location, is summarized below.


Structural integrity catastrophic loss


Houses located in a forest are far less likely to be damaged by fire if the roof, sofit, and walls are metal or concrete, and vegetation and other flammable material is not close to the house. The Cave House has steel siding, roof and sofit. Fires can start inside a house, and when they do, steel houses are better at containing the fire where it starts, primarily by not contributing combustible material to the fire. Most houses have combustible furnishings, so a completely fire-poof house would be difficult to build, and probably no one would find it very pleasant.


Wind, Tornados, Hurricanes

In the aftermath of hurricanes and tornados, it is not unusual to see that the only buildings left standing are either steel or reinforced concrete. Wood frame houses are notoriously poor at withstanding high winds. The usual sequence of destruction of a wooden house in very high winds is that the roof is blown off and then walls fall down. The Cave House is constructed of red steel beams with diagonal braces. There have been no recorded hurricanes or tornados to strike Kau, Hawaii. High winds are common in Kau; however, the ridge of lava just west of the Cave House from the 1907 lava flow provides some wind protection.


Floods and Tsunamis

Building in a flood plain or below sea level could be considered high risk behavior. Steel buildings will withstand floods and waves much better than wood; however, a better solution is to build on high ground. The Cave House is several miles from the ocean and about 1000 feet in elevation. Anything that causes a tsunami that large will most likely disrupt the entire planet and the damages to one house will be of little consequence in the overall scheme of things.



Hawaii has small earthquakes everyday; most of these can not be detected without seismographs. On rare occasions large earthquakes do occur. Steel buildings are designed to withstand earthquakes much better than wood frame houses and stone buildings.



With the exception of cold places such as Montana, the Dakotas, Minnesota, Maine, Canada, Siberia, and Antarctica, termites are everywhere wood is. Hawaii might as well be termite paradise with its full-time warm, moist climate. Termites cause more than $100 million worth of damage each year in Hawaii. The worst is the Formosan Subterranean termite, which came from China. They somehow manage to get past concrete, bricks or mortar to reach wood. They have even been known to mistakenly chew through many other materials in search of wood, including insulation around underground electrical lines, causing power outages. The best solution is not to feed them. Start with an all steel or reinforced concrete house, keep inside wood furniture dry, and do not have any wooden items or dead trees or branches near the house. Wooden cabinets are vulnerable to termites, but substantially less so in a steel house. The Cave House is mostly impervious to termites and other pests, such as powder post beetles and rot.



The Cave House is in Lava Zone Two, a high risk zone classification. Lava flows are an ongoing event in Hawaii and all very recent ones have been near Hawaii Volcano National Park and associated with the Kilauea area. Flows are difficult to predict, but risk managers demand some scientifically based document upon which they can make decisions. Maps showing volcanic hazard zones on the island of Hawaii were first prepared in 1974 by Donal Mullineaux and Donald Peterson of the U.S. Geological Survey and were revised in 1987. The authors state that the “hazard assessment is based on the assumption that future eruptions will be similar to those in the past.” Everyone might do well to also consider the warning used in evaluating stocks and mutual funds: "Past performance is no guarantee of future results."   


They further state that “hazard zone boundaries are approximate. The change in the degree of hazard from one zone to the next is generally gradual rather than abrupt, and the change can occur over the distance of a mile or more. Within a single hazard zone, the severity of hazard may vary on a scale too fine to map. These variations may be the result of gradual changes that extend across the entire zone. For example, the hazard posed by lava flows decreases gradually as the distance from vents increases.”


My assessment of this map is that it is reasonably helpful in determining the likelihood of a lava flow in a particular place in Hawaii over the next 5,000 to 10,000 years and that it is almost useless in determining the risk of a lava flow in the next 30 years. Kula Kai appears to have less than average risk for Zone Two based on elevation, distance, and other factors. Should a lava flow come to the Cave House, there is one consolation. Lava in Hawaii moves slowly enough to allow anyone using good judgment to get out of its way.


Some people are reading more into the Lava Zone maps than was probably intended. Over time, markets have a way correcting poor prognostics such as “the lava is coming to Kau.” The Ocean View area real-estate market remained depressed for many years due to a variety of factors including the Lava Zone map; however, in recent year the market is reflecting some skepticism on the rational behind the Lava Zone map. The price of land and the quality of new building have both substantially increased in the Kau District.  It is plausible that a better model that reflects a regional sequence for lava flow would be a more useful and accurate tool. 


The Lava Zone map provides insurance underwriters criteria for rejecting all policies in Zones one and two; and allows Lloyds of London to make big profits on policies in these two zones.  Full time residents can get limited insurance coverage through the Hawaii Property Insurance Association - HPIA, PO box 2880 Honolulu, HI 96802-2880, phone: (808) 564-8200, fax: (808) 564-8457.


Maintenance and Warranty

Steel houses have very low maintenance, low upkeep costs, and low insurance costs. Steel buildings often have a paint warranty as well as a lifetime structure warranty. Steel houses use treated steel that is not affected by water damage and does not expand or contract, swell if wet, or crack if too dry. Steel does not warp over time and rot as does wood. The walls, ceilings, and roof remain strong and straight; doors don’t stick, walls don’t bend; ceilings don’t sag; and floors don’t squeak.


Health and Environment

Wooden houses must be constructed with treated lumber and receive regular chemical treatments to limit termite damage. During the lifetime of the wooden house, there is the continuing cost of the termite treatments and the risk that the treatment will be done unsafely at some time. When the house is replaced, most of this wooden material contains toxic chemicals that must be processed appropriately or cause environmental contamination.


Energy Conservation

Hawaii is located in the middle of the Pacific Ocean, which happens to be the largest surface heat sink on the planet. Heat sinks help to stabilize the surrounding temperature. Depending on the base temperature, houses in Hawaii that are properly insulated can eliminate the need for heating and air-conditioning systems. The base or average temperature at sea level in Hawaii varies from about 73 degrees in winter to 80 degrees in summer. Since temperature decreases with elevation by about 3 degrees per thousand feet, the seasonal average temperature range at the cave house is about 70 to 77 degrees. The average day to night temperature change is about 15 degrees.

Most people find the 70 to 77 degrees comfortable, especially with the low humidity typical in semiarid Kau. The well insulated Cave House stabilizes the daily temperature swings, keeping the temperature in comfort zone without requiring energy-intensive heating and cooling systems.


Flexibility of Design

The nature of steel allows far more options than wood. The strength to weight ratio of steel is the highest of any residential building material, and it can be easily formed and joined. For the Cave House, the steel design provides a clean span for the great room of 33 feet. This was much easier with steel than wood, and the first floor rooms could be made in any configuration. In fact the location of several internal walls was changed from the original plans with no additional cost.


Expediting the permit and design and construction process

The pre-engineered design expedited the Hawaii County approval process. Pre-cut steel material simplified the construction process and allowed the primary structure to be quickly bolted together. The entire process, including selecting a general contractor (Ray Kevis), selecting a building manufacturer (which was Kodiak Steel Homes), county approval, and construction, took about a year.


Accuracy and Ease of Construction

The Kodiak steel house was mostly prefabricated, so its construction was less noisy, less dusty, faster, and cheaper.