Case Study: Hurricane Protection for a U.S. Navy Hospital in Guam
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Summary. The HS-1500 hurricane fabric system was used on a U.S. Navy hospital replacement project in Guam, an island in one of the most active tropical-cyclone regions on Earth. The Navy’s construction specification required the fabric protection system to withstand winds of 274 km/h (about 170 mph), to be installed with stainless-steel hardware, and to be inspected in the presence of the Navy’s contracting officer.
Summary
A hospital is the clearest example of what ASTM E1996, the most widely referenced standard for hurricane impact protection, calls an essential facility: a building that has to keep working during and after a storm. For essential facilities in the highest wind zones, the standard reserves its most demanding missile level, Level E. The HS-1500 is tested to that level.
This case study explains what the Navy required, what those requirements mean in engineering terms, why Level E is the right benchmark for a hospital, and what owners of essential facilities in Mexico can learn from it.
Project facts
| Item | Detail |
|---|---|
| Facility | U.S. Navy hospital replacement project, Guam |
| Specification | Section 10 71 13.13, Storm Protection |
| System used | HS-1500 hurricane fabric system |
| Required wind resistance (fabric system) | 274 km/h (about 170 mph, 148 knots) |
| Complementary system | Motorized aluminum rolling shutters: 6.7 kPa (about 140 psf) on windows, 5.27 kPa (about 110 psf) on entrances |
| Hardware | Stainless-steel fasteners; concealed metal surfaces in stainless steel |
| Deliverables | Shop drawings, product data, and operation and maintenance manuals subject to government approval |
| Oversight | Inspections in the presence of the contracting officer; written report within two working days |
| Product test standard | ASTM E1996, missile level E (9-pound lumber missile at 80 feet per second, followed by 9,000 pressure cycles) |
The context: Guam and the western Pacific
Guam lies in the western North Pacific, the most active tropical-cyclone basin in the world. There, storms are called typhoons, but they are the same phenomenon as Atlantic and eastern Pacific hurricanes, and the island has taken direct or near hits from very strong storms many times. In May 2023, Typhoon Mawar passed just north of the island as a major storm, a reminder that Guam lives with this risk routinely.
The Navy’s specification reflects that reality. It begins by defining tropical cyclones in international terms: a tropical storm has winds of 63 to 117 km/h, and a typhoon has winds of 119 km/h or more. It also defines the warnings the hospital must respond to, from a gale warning for winds of 63 to 87 km/h up to a typhoon warning for sustained winds of 119 km/h expected within 24 hours or less. All speeds are measured 10 meters above ground level, the international meteorological convention.
The challenge: a hospital that cannot close
For most buildings, a storm means closing and waiting. A hospital does the opposite. It has to keep treating patients while the storm passes, and it has to take in more patients when it ends. Its emergency department, operating rooms, intensive care unit and inpatient floors cannot be evacuated every time a typhoon warning is issued.
That makes the building envelope, its walls, windows and doors, part of the hospital’s medical infrastructure. If a window breaks, the damage does not stop at the glass:
- Internal pressurization. Wind entering through a broken opening pressurizes the interior. The ASTM E1996 appendix explains that when a building loses its envelope, its internal pressure coefficient can rise from 0.18 to 0.55, more than triple, pushing outward against the roof, walls and remaining glazing with far more force than they were designed for.
- Water intrusion. Wind-driven rain enters through the opening and spreads across ceilings and floors, damaging electrical systems, medical equipment and sterile areas.
- Loss of service. A single failed opening can take a floor, an operating room or an emergency department out of service just when the community needs it most.
What the Navy required
The specification combined two types of storm protection, each assigned to the openings where it made the most sense.
Rolling shutters for certain windows and entrances: extruded aluminum slats, a spring-counterbalanced shaft, 120-volt motorized operation with a manual crank in case of power failure, and coordination with the hospital’s smoke-exhaust system. Window shutters had to resist a minimum wind load of 6.7 kPa, about 140 pounds per square foot, and entrance shutters 5.27 kPa, about 110 pounds per square foot, with deflection limited to 1/30 of the opening width and at least 25 mm of clearance from the glass.
A fabric protection system was specified alongside them: fabric, bolts, anchors, end connectors and every component needed for a complete system, fabricated and installed to withstand winds of 274 km/h. The specification treated the fabric as a system, not just a material: the anchors and connectors were part of the requirement.
What 274 km/h means
A wind speed of 274 km/h is about 170 mph, or 148 knots. That is more than double the 119 km/h the specification uses to define a typhoon.
The difference is larger than it looks, because wind pressure grows with the square of wind speed. Doubling the speed quadruples the pressure. At 274 km/h, the wind pushes on a surface with roughly five times the force it exerts at the typhoon threshold. A protection system designed for 274 km/h is not meant for an ordinary typhoon; it is meant for a severe one.
Requirements beyond the product
The Navy did not stop at performance figures. The specification also controlled how the protection was documented, built and verified.
- Documentation before installation. Shop drawings had to show elevations, sections, material thicknesses and gauges, the anchoring method, anchor size and spacing, hardware locations, and how the system connects to adjacent windows and walls. Product data for the fabric system and its accessories was required, and the operation and maintenance manuals needed government approval.
- Corrosion-resistant hardware. The entire installation used stainless-steel fasteners, and concealed metal surfaces had to be stainless steel. Where aluminum touched concrete, masonry, wood or dissimilar metals, it had to be protected. On a tropical island with constant salt air, corrosion is not a cosmetic issue: a corroded anchor is a weak anchor.
- Made to measure. Every opening had to be field-measured before fabrication, so that each piece matched the actual opening and not a drawing.
- Inspected installation. The manufacturer’s technical representative had to visit the site during installation. Inspections were made in the presence of the Navy’s contracting officer, and a written report was due within two working days on compliance with the manufacturer’s instructions, workmanship, deficiencies and corrective actions. Afterward, each shutter was tested in front of the contracting officer.
This is what serious hurricane protection looks like on an essential facility: a tested product, documented anchoring, corrosion-resistant hardware and independent on-site verification.
The system: HS-1500
The HS-1500 hurricane fabric system was used. Fabric screens work well in hospitals for several reasons:
- They cover large and irregular openings without the weight or bulk of rigid panels.
- They store compactly and leave no boxes on the façade when they are not deployed.
- They do not depend on electrical power. There are no motors or tracks that can fail when power is uncertain, which is exactly when a hospital needs its protection.
- They resist salt air with no mechanical parts to corrode, as long as the anchoring hardware is stainless steel, as the specification required.
Combined with motorized rolling shutters where they make sense, fabric screens let a facility give each opening the type of protection that suits it best.
Why Level E matters for a hospital
ASTM E1996 classifies buildings into three protection levels and assigns the test missile according to the protection level, the wind zone and the height of the opening.
| Protection level | Which buildings | Missile in the highest wind zones (up to 9.1 m) |
|---|---|---|
| Enhanced Protection | Essential facilities: hospitals and health care facilities with emergency services, fire and police stations, emergency shelters, services needed in an emergency, buildings with critical national defense functions | Level E: 9-pound lumber at 80 feet per second |
| Basic Protection | All other buildings, except those classified as unprotected | Level D: 9-pound lumber at 50 feet per second |
| Unprotected | Low-risk buildings such as agricultural and storage facilities | None |
Levels D and E use the same missile: a 2x4-inch piece of lumber, 8 feet long and weighing 9 pounds. The only difference is speed, and speed matters a great deal. Impact energy grows with the square of speed, so the Level E missile at 80 feet per second hits with about 2.5 times the energy of the Level D missile at 50 feet per second.
The test does not end with the impact. After the hit, the system goes through 9,000 cycles of positive and negative wind pressure, simulating hours of gusts pushing and pulling on an already damaged surface.
For essential facilities, the pass criterion is also stricter. On ordinary buildings, a system can pass with limited tears, as long as no tear exceeds 130 mm by 1 mm and no opening admits a 76 mm sphere. On essential facilities, the missile may not penetrate the inner plane of the protection system. The standard also requires non-porous systems on essential facilities to be separated from the glass by at least their measured deflection plus 2 mm, so that the protection never touches the window it protects.
Finally, the standard states that qualifying at one level automatically includes all lower levels. A system tested to Level E has passed the test the standard reserves for hospitals and, with it, the levels set for ordinary buildings.
To be precise: the Navy’s specification set its own requirement, a wind speed of 274 km/h, and did not cite ASTM E1996. The two documents measure different things: wind speed on one side, impact and pressure resistance on the other. What they share is the conclusion that a hospital in a region of severe storms needs protection far above the ordinary. The HS-1500 is tested to the level that the leading impact standard assigns to buildings like this one.
Lessons for essential facilities in Mexico
Hospitals, clinics, emergency shelters, police and fire stations, utility facilities and government buildings on Mexico’s coasts face the same storms as Guam. Hurricane Otis hit Acapulco as a Category 5 in 2023; Wilma, Beryl and Milton have tested the Yucatán Peninsula. The Guam specification offers a clear model for protecting buildings that cannot close:
- Choose protection by the essential-facility standard. If a building has to stay open when a hurricane arrives, choose its protection by the level written for essential facilities, not the one for ordinary buildings.
- Specify the anchoring, not just the product. Require shop drawings that show the type, size and spacing of anchors, and how the system connects to the actual structure.
- Require stainless-steel hardware in coastal areas. Salt air turns ordinary steel into a weak point within a few seasons.
- Plan for a power failure. A hospital’s protection must be deployable without electricity, either with a manual mechanism or with systems that never needed power.
- Verify the installation independently. Inspections, written reports and operational tests are what turn a specification into a protected building.
Learn more about our approach to hurricane protection, or how we protect hotels and commercial properties. Another real project: the DIF Solidaridad case study.
Frequent questions
What wind speed did the Navy require for the fabric protection system?
The specification required the fabric protection system to be fabricated and installed to withstand winds of 274 km/h, about 170 mph.
What is ASTM E1996 Level E?
It is the most demanding missile level in ASTM E1996: a 9-pound lumber missile at 80 feet per second, followed by 9,000 pressure cycles. The standard assigns it to essential facilities, such as hospitals, in the highest wind zones.
How is Level E different from Level D?
Both use the same 9-pound lumber missile. Level D fires it at 50 feet per second; Level E at 80 feet per second, which produces about 2.5 times the impact energy. Level E also comes with stricter pass criteria for essential facilities.
Why do hospitals need a higher level of protection?
Because they have to keep operating during and after a storm. If an opening fails, wind and water can take patient areas out of service when they are needed most.
Why use fabric screens on a hospital instead of only shutters?
Fabric screens cover large and irregular openings, store compactly and do not depend on electrical power. On the Guam project, the Navy specified fabric protection alongside motorized rolling shutters, giving each type of opening the system that suits it best.
Is the HS-1500 available in Mexico?
Yes. Hurricane Solution installs the HS-1500 in hotels, essential facilities and other properties throughout Mexico. Hurricane Solution is also the only member of the International Hurricane Protection Association outside the United States; learn what that means.
Does your building have to stay open when a hurricane arrives?
Hurricane Solution assesses your openings by the essential-facility standard.