On the morning of May 20, 2013, a massive EF5 tornado cut through Moore, Oklahoma, destroying 1,091 homes and killing 24 people — including 7 children at Plaza Towers Elementary School. The tornado followed nearly the same path as the F5 that had struck Moore in 1999. For a community that had already rebuilt once from catastrophic destruction, that repetition was not just tragic. It was clarifying.

Less than a year later, on March 17, 2014, Moore became the first city in the United States to adopt a residential building code requiring structures to withstand 135 mph wind loads. The code took effect on April 17, 2014. It was a landmark decision that reflected both the community’s hard-won experience with tornado damage and a serious effort to answer the question: what can we actually build differently to give people a better chance?

Why Moore Has This Code: The Tornado History

To understand why Moore took this step, it helps to understand how unusual Moore’s tornado history actually is. According to National Weather Service records, approximately 175 tornadoes have tracked near Moore since 1893. No other community in the country has experienced that kind of repeated, documented exposure to violent tornado activity.

The 1999 F5 tornado — which struck on May 3, 1999 — set a record that still stands. Doppler radar measured wind speeds exceeding 302 mph, the highest ever recorded at the time. It caused $1 billion in damage, making it the first billion-dollar tornado in American history. Neighborhoods including Country Place Estates and the Greenbriar and Eastlake Estates areas were devastated.

When the 2013 EF5 traced almost the same path through Moore, the community faced a stark reality: the homes that had been rebuilt after 1999 were built to the same codes as the ones they replaced. They failed the same way. The question of whether building codes could be improved to change that outcome became unavoidable.

What the 135 MPH Code Actually Requires

The 135 mph standard was developed with input from University of Oklahoma professors Dr. Chris Ramseyer of the Civil Engineering department and Dr. Lisa Holiday of the Construction Science department. Their research identified the specific structural failure points in residential construction during high-wind events and informed the specific requirements the code adopted.

The code requires five primary structural enhancements that work together as a system:

Hurricane straps. Metal connectors that tie the roof framing directly to the wall studs. Without hurricane straps, the connection between the roof system and the wall is made through nails alone — and under high-wind uplift loads, those connections can fail and allow the roof to separate from the walls. Hurricane straps dramatically increase the strength of that connection.

Foundation anchors. Anchors that tie the wall framing to the foundation. The same principle applies vertically as horizontally: in high winds, the entire structure can be lifted or shifted if the wall-to-foundation connection is insufficient. Foundation anchors complete the structural chain from roof to foundation.

Continuous OSB sheathing at the perimeter. Oriented strand board sheathing around the full perimeter of the building creates a continuous structural skin that distributes wind loads more effectively than sheathing applied only at corners.

Closer-spaced rafters. Reducing rafter spacing increases the structural redundancy of the roof system and reduces the span over which each rafter must resist uplift forces.

Garage doors rated for 135 mph. Garage doors are one of the most common failure points in residential structures during high-wind events. Once a garage door fails, the change in internal pressure can accelerate failure of the rest of the structure. The code requires garage doors rated to withstand 135 mph wind loads.

The total cost impact of these requirements is approximately $1 per square foot of living space — a relatively small addition to total construction cost for a meaningful structural improvement.

What the Code Does Not Cover

Mayor Glenn Lewis was direct about this when the code was adopted: the 135 mph standard protects against EF2 and EF3 range storms. It does not protect against a direct EF5 hit. A tornado with winds exceeding 200 mph will destroy a home built to the 135 mph standard, just as it destroys everything else in its direct path.

This is an honest and important limitation to state clearly. The value of the code is not that it makes homes tornado-proof — nothing short of underground shelter makes a home tornado-proof against a direct EF4 or EF5 hit. The value is that EF2 and EF3 tornadoes are far more common than EF4 and EF5 events, and homes built to the 135 mph standard perform significantly better in those events. The code reduces damage and saves lives in the range of storms that occur most frequently.

There is also a geographic point worth making. A tornado does not damage everything in its path equally. The most violent damage is concentrated in the central track. Homes at the edge of a tornado’s path — even a significant one — may experience EF2 or EF3 wind speeds rather than the EF5 peak. For those homes, the 135 mph standard can be the difference between surviving with structural damage versus total loss.

Does the Code Apply to Roof Replacements?

This is a question we hear frequently, and the answer is no. The 135 mph structural standard applies to new construction. If you own an existing home in Moore and replace your shingles, you are not required to meet the new structural code requirements. The hurricane straps, foundation anchors, and continuous sheathing are elements of the structural framing system — they are not part of a roofing replacement project on an existing home.

What a roof replacement does affect is the quality and installation of the roofing surface itself. A properly installed roof on an existing home — with correct fastening patterns, proper overlap, sealed penetrations, and quality shingles — performs better in high-wind events than one that is poorly installed regardless of what the underlying structure looks like. Impact-resistant shingles (Class 4 rated) provide meaningful additional protection against Oklahoma’s frequent large-hail events.

For Moore homeowners specifically, Wilson & Sons provides roofing services including complete roof replacement in Moore, OK. We understand the specific context Moore homeowners face and ensure installations meet the quality standards that matter in this environment.

Lessons for Other Oklahoma Homeowners

Moore’s building code is specific to new construction within Moore’s city limits. The broader Oklahoma City metro area, and the vast majority of Oklahoma communities, have not adopted the same standard. But the underlying lessons are relevant for every Oklahoma homeowner.

The connection between roof and wall, and between wall and foundation, is the critical structural chain that determines how a home performs under high-wind loads. For homeowners doing renovations or additions, asking specifically about how structural connections are being made is worth the conversation. For anyone building new, asking your contractor whether they are incorporating enhanced connection details — even in jurisdictions that do not require it — is a legitimate and reasonable question.

For the roofing surface itself, material choice and installation quality both matter. Impact-resistant shingles are available at Class 4 ratings — the highest category — and they are tested under the UL 2218 standard. Oklahoma’s hail frequency makes Class 4 shingles a practical investment for most homeowners in the metro area, not just those in Moore.

The NWS Norman office, which covers central Oklahoma, tracks severe weather data that puts Oklahoma’s risk in context. According to NOAA’s Storm Prediction Center, Oklahoma consistently ranks among the highest-risk states for large hail and significant tornadoes. Moore’s response to that reality — taking the unprecedented step of requiring 135 mph construction — represents one model of how communities can engage seriously with risk. For individual homeowners throughout Oklahoma, the lesson is similar: taking the risk seriously before a storm arrives is dramatically less expensive than responding after one.

Community Development and Permit Requirements

For homeowners and contractors working in Moore, all new construction and significant structural work must comply with the 135 mph code. Permit requirements and code verification are handled through Moore’s Community Development department. Wilson & Sons is familiar with Moore’s permitting process and builds that process into project timelines for work within the city.