Disaster Resistance

Hurricane, Tornado, Earthquake, Fire and Flood Resistance through Ferrocement Technology & Engineering


Image (Filer) - VS ADDITION POOL LOWER.jpgJust how strong is the am-cor System? Click here to see an example of the Link - am-cor System's Real World Disaster Resistance during Hurricane Ivan.

The am-cor System employs a frame geometry that counteracts structural deformation due to hurricane wind forces, and provides direct anchorage of each structural member in the foundation. In the am-cor System, all forces on the structure from any direction are transferred directly to the foundation.

am-cor roof and wall frame members, and roof truss members, are fastened together directly. All wall members are directly imbedded in the reinforced concrete foundation, resulting in a solid and strong building shell capable of withstanding hurricane force winds.

Hurricane damage to metal shingle or tile roof surfaces is often due to structural deformation of the building frame; this motion can loosen roofing fasteners over time. Structural deformation can start off small, but may increase with exposure to successive storms. Minor motion of the structure can cause surface cracks and fissures, which allow water penetration causing rot and weakening of a wooden frame, as well as promoting growth of mildew, mold, bacteria and fungus growth in wall cavities.

In standard framing, rafters are not directly connected to wall studs, but are anchored using pliable straps via a wall plate. The anchors can change shape under stress, and the fasteners at the top plate can come loose. Wooden truss design does not call for direct connection between members; they are joined by plates alongside the members, which do not resist sideways motion due to wind.

Anchorage to foundation is another weak point in standard design, not just in wooden frames, but in reinforced masonry also. Wooden frames are required to have anchors at 6 feet on center, resulting in high concentrations of pull out force at the anchors. The vertical members (studs) are not directly fastened to the anchors, but via a sill plate member (another joint to work loose).

Reinforcing bars in block cavities are also insufficient as hurricane anchorage, because lateral wind force can cause the grout in its cavity to slip off the bar allowing the wall to overturn. Again, standard unit masonry is not anchored directly to the foundation, but through grouted block cavities. Trusses are not anchored directly to the masonry, but to a top plate which is then anchored to a grouted cavity. With the am-cor System, am-cor structural joints require steel members to overlap, and several fasteners are used at each joint to resist rotation. Resistance to rotation is the key to structural stability; if the structure remains stable, surface elements such as shingles, tiles, and metal roofing will remain in place based on the uplift rating of their fasteners. Surfaces will not admit moisture, so stability and durability will be maintained through successive storms.

The am-cor System utilizes an extremely rigid steel frame coated with reinforced waterproofed cement. This shell consists of all galvanized steel and cement, so there is no rust or deterioration with moisture. In a hurricane, an am-cor unified steel and cement shells resist hurricane wind forces without sustaining structural damage.

The am-cor System™ offers sustainable and fortified resistance to disasters such as hurricanes, earthquakes, tornados, fires, and floods.


Image (Filer) - casino rough coat 2.jpgIn regions subject to tornados, am-cor structures include thin reinforced concrete roof slabs cast on am-cor steel roof framing, for optimum resistance to the sucking force of tornado winds. The concrete roof slabs and parapets are coated with ceramcorite seamless white ceramic cement roofing which bonds directly to the concrete to form a completely impervious china-like surface, resistant to blow-off.

Parapet walls give a Southwest appearance. Eave overhangs are kept to a minimum in order avoid providing handles for the wind to pull up. Doors are protected by porches, and windows are protected by enamel steel security shutters.

Exterior wall frames are placed on the top of the footings and are imbedded in the concrete floor slab. The rafters overlap imbedded wall studs, so that pull-up force on the roof is transmitted directly to the footings. The whole structure is structurally grounded, and unified by the continuous amcorite Ferrocement skin, so that no part can be torn off by the wind.


Image (Filer) - am-cor wall cavity double sided amcorite.jpgFire is a constant danger in any building, and wildfire is a serious threat during dry months in arid climates, such as the American West. All am-cor materials are completely fireproof and non-combustible, have a zero flame spread rating, and do not out-gas under extreme heat. All walls and intermediate floors are UL rated and approved by the International Building Code (IBC), even for incapacitated occupancy. In the event of a fire, the furniture and other contents of a building may sustain smoke damage; however, an am-cor structure will not burn or collapse, allowing occupants a greater chance of escape.

The steel frame superstructure is surrounded by a highly reinforced amcorite cement skin. This type of structure has a UL 2-hour fire rating. Please see our Link - Code Compliance section for more information.

am-cor buildings can be designed to be fire resistant inside as well as out:

  • interior partitions and floors are framed in galvanized steel, not wood
  • am-cor steel staircase kits
  • thin reinforced concrete intermediate floor diaphragms 
  • fire rated gypsum drywall to interior wall & partition surfaces
  • enamel steel structural roof tile and roof trim
  • enamel steel security shutters to windows
  • enamel steel insulated hollow core exterior doors


An am-cor building is a life saving structure with a high strength to weight ratio. During seismic events, an am-cor unified steel & cement frame may deform, but will not collapse because of deformation. An am-cor shell's walls, floors and roofs may warp, but will not fall on occupants, and can be repaired.

The majority of deaths caused by earthquakes are due to inhabitants being crushed by falling concrete debris. This cannot occur in an am-cor building!

Seismic disturbances act in the form of a wavelike undulation of the earth’s surface, placing extreme stress on the foundation of a building. If the foundation is unable to resist such motion, stresses are transferred to and multiplied in the superstructure. In traditional structures, the weight of the building, and the method of footing reinforcement result in foundations incapable of resisting cracking and displacement during seismic activity. Traditional frames are so heavy that when tilting places their center of gravity outside their footprint, they exert lateral forces on adjacent frames, causing the building to collapse in “domino” fashion (progressive collapse). Inhabitants are in danger of being crushed by collapse of the structure itself.

am-cor structures are earthquake resistant in 5 ways:

  • am-cor structures are a fraction of the weight of traditional masonry and concrete structures built to be earthquake resistant
  • am-cor foundation walls are designed as galvanized steel trusses imbedded in concrete to be many times the strength of most foundations
  • am-cor cellular superstructures are highly resistant to progressive collapse, since each “cell” is a complete 3-dimensional structure; if the foundation moves, stresses transferred to the frame will not result in collapse or endanger lives of building inhabitants
  • am-cor structural members are “glued” together by their bond to the continuous amcorite™ unibody Ferrocement skin, and are imbedded in concrete floor slab diaphragms at each level. This unified steel & cement composite structure is many times stronger than other structures held together by fasteners
  • am-cor slab diaphragms are constructed in the same manner as the exterior walls; cannot fall onto the level below, even if it cracks to bits

Strength to weight ratio is the key to structural resistance to lateral force. If all forces were perpendicular to the earth, then a structure of any weight would stand forever as long as its foundation was sufficient. However, when wind or flood forces occur horizontal to the earth’s surface, or when seismic disturbances cause movement of the foundation, the weight of structural members becomes the enemy of the rest of the structure. Tilting members will tend to “fall” against adjacent members.

Image (Filer) - am-cor floor assembly detail.jpgam-cor Galvanized frame exterior wall panels are placed and secured directly to the top of the footing. The concrete ground floor slab and foundation wall imbed these vertical steel studs and their track. The steel wall frame acts like a Vierendeel truss to stabilize the footing and unify the ground floor slab with the footing, creating a highly resistive 3-dimensional structural grade cell. Each independent grade cell in am-cor seismic design is capable of “riding” undulating wave-like motion of the earth’s crust with minimal deformation, so minimum stress is transmitted to the superstructure.

Steel cannot be broken; it will bend and stretch instead. Thin Link - Ferrocement amcorite wall skins and thin concrete floor slabs cast on steel diaphragms are supported by their steel matrices, and so do not collapse or fall during earthquake. Inhabitants will not be crushed by falling walls and slabs. In standard reinforced concrete construction reinforcing bars are placed from 4” to 8” apart. This leaves cement molecules as far as from 2” to 4” from steel. Only cement in conjunction with steel is structurally active; the remaining unreinforced concrete mass is incapable of withstanding tension stress. This non-structural dead weight will crack, spall, and, under extreme conditions, break away from the slab, column, or wall. It will not only initiate structural collapse, but will also become deadly debris.

Concrete weighs 150 lbs. per cubic foot; standard reinforced concrete and masonry buildings with walls and floors from 6” to 8” thick are heavy enough to precipitate collapse once they move beyond their center of gravity.

It is during seismic events that the high strength-to-weight ratio of am-cor structures really counts. The galvanized structural expanded carbon steel surface offers many more times the steel-to-cement surface area than standard reinforcing bar, at a fraction of the bar’s weight. No cement molecule in the am-cor System is more that 1/4” away from steel reinforcement. These factors make am-cor structures truly composite, a wedding of steel and concrete. There is no dead weight in an am-cor slab.

In addition, the am-cor steel framework can stand on its own, whereas reinforcing bars in a traditional design cannot. So even under the most extreme twisting and shaking, even if the cement is literally wrenched from walls and floors, the framework might bend, but does not collapse. Flakes and cement dust may filter down, but the structure will not fall and crush its inhabitants.

The am-cor System is a life-saving construction method in earthquake zones.


Image (Filer) - flood resistant basement.jpgIn the event of flooding, am-cor unified steel and cement shells resist flood waters and subsequent sitting moisture with minimum sustained structural damage.

Where buildings are subject to flooding, am-cor structures include a raised first floor level with continuous galvanized steel stud panels from footer to roof. The steel frame is coated both sides with amcorite Ferrocement structural stucco, creating a series of stress-skin panels to unify the superstructure with its foundation. am-cor structures do not wash away in floods, and are strong enough to resist motion of floodwaters.

Lateral forces of wind and water are resisted by first floor walls and partitions which are designed as a series of truss frames. The truss frames are integral with the stress skin panels and so stabilize them against tilting. The thin reinforced concrete first floor slab is cast on galvanized steel ceiling trays which are in turn fastened to a steel first floor framework. This horizontal concrete diaphragm resists torsion and twisting caused by water washing against the stress skin panel flood frame.

Wooden buildings that last through floods are often subject to long term damage due to damp, mildew, rot, fungus, and bacteria in their wall cavities. The wooden frame expands with moisture, forcing fasteners out, and when it finally dries out and shrinks, members no longer touch each other, held apart by the partially pulled-out fasteners. For example, Wood-framed homes in the Gulf coast region are constantly being rebuilt due to this type of damage, as seen in the aftermath of Hurricane Katrina.

Steel and concrete do not expand with moisture, and so do not over-stress their fasteners by swelling after a flood. Even if water enters wall cavities, damage is minimal because steel is galvanized, and the cement skin “breathes” which means that excess moisture can escape in the form of water vapor once sunlight hits wall surfaces. am-cor frame cavities do not have the residual sugar in wood to support mold, mildew, fungus or bacteria.

am-cor flood resistant design has been approved by the U. S. Army Corps of Engineers for construction along the eastern seaboard of the United States. Flood relief vents are not required with am-cor flood resistant foundations. Please see our Link - Code Compliance section for other qualifications of the am-cor System.

  • Hurricane Ivan Impact
    A real world example of how am-cor Prefab Ferrocement not only weathers destructive Hurricanes & Floods to protect inhabitants, but also is easily repaired