Concrete or metal: which one holds up in a hurricane?

Engineered to a 170 mph ultimate design wind speed.

That number is not a sustained wind speed, and it is not the Saffir-Simpson category rating you hear on the news. It is a 3-second gust measured at 33 feet above open, flat ground (Exposure C), used as an input to a structural design equation, at a specified statistical recurrence interval. A Category 4 storm's sustained wind and a building's ultimate design wind speed are two different numbers measuring two different things, and conflating them is the single most common mistake in this conversation.

A pre-engineered metal building (PEMB) is a steel frame, columns and rigid rafters, clad in formed metal panels attached to horizontal girts. The frame carries the load; the panels are a skin, screwed down at a specified fastener spacing calculated to resist the design wind pressure at that particular wall zone (corners and eaves see higher suction than the middle of a wall). Done correctly, to the calculated fastener schedule, a PEMB is fully code-compliant at any design wind speed, including 170 mph. Done with the wrong screw pattern or the wrong gauge panel, it is not, and the failure mode is panels peeling back from the corners inward.

Reinforced concrete, tilt-wall panels or CMU block with vertical steel reinforcing and grout-filled cells, behaves differently. Mass and continuity mean the wall itself resists wind pressure and impact without depending on a fastener schedule to hold a thin skin in place. Filled and reinforced CMU cells tie the wall to the foundation and the roof structure as a continuous load path, which is the concept structural engineers call a "continuous load path" from roof to footing.

In practice: a correctly engineered building of either type meets the same code requirement, because the code sets the performance target and each material has an accepted engineering path to get there. Concrete gives you more margin for error in the field. Metal, done right, gives you a lighter, faster-to-build structure at the same rated performance.

Wind does not push down on a roof, it pulls up. As air moves over a roof surface it accelerates, dropping pressure above the roof relative to inside the building, the same principle as an airplane wing. That suction, called uplift, is highest at roof corners and edges because that is where airflow separates and accelerates the most. This is why you almost never see a hurricane-damaged roof fail in the middle first; it starts at a corner or an eave, where fastener pull-out or a compromised deck seam gives way, and then peels inward.

A 60-mil TPO roof membrane is only as good as what it is mechanically fastened or fully adhered to underneath. The membrane sheds water; the deck attachment and the fastener pattern are what resist uplift. This is the part of a building nobody photographs and everybody should ask about.

A 16-foot-wide, 14-foot-high door is the biggest hole in an otherwise closed envelope, and it is engineered and rated for the same design wind pressure as the walls around it, including large-missile impact requirements for wind-borne debris regions. That rating matters more than the wall material next to it, because in a design-level event the door sees the same suction and impact loading as the roof and walls, on a much larger unsupported span.

Here is the mechanism worth understanding: a building envelope is designed to stay sealed. If a garage door, a window, or any large opening fails, from missile impact, from a pressure spike, from age and poor maintenance on the hardware, outside air rushes in and the interior pressurizes. That internal pressure adds to the external suction already pulling up on the roof from outside. This is why so much storm damage footage shows a roof lifting off from the inside, after a door or window has already gone. The wall material did not fail; the opening did, and the physics took over from there.

That is also why we say plainly, and will keep saying: no building is invulnerable.