The Wooden Plank Under an F1 Car | A Safety Limit Beneath the Car

When an F1 car travels at high speed through a corner or over an uneven section of track, the bottom of the car may scrape against the road and produce a trail of bright white sparks. This is especially noticeable during night races.

Those sparks come from an area around a long board called the Plank, which runs along the center of the underside of the car. Metal skid blocks are fitted around the Plank. When the car runs low enough for these metal parts to touch the track, friction creates the sparks we see during a race.

Interestingly, the word “Plank” literally means a flat piece of wood—and the original F1 Plank was indeed made from a wood-based material.
 

After F1 introduced flat-bottom regulations, teams tried to run their cars as low as possible to improve grip and aerodynamic performance.

However, when the bottom of a car frequently touched the track, the car could become less stable.
At the 1994 San Marino Grand Prix, motorsport experienced a tragic weekend.

During qualifying, Roland Ratzenberger suffered a front-wing failure. His car lost control and crashed into a concrete wall, resulting in his death.
The following day, three-time World Champion Ayrton Senna lost control while cornering and crashed into a wall. He also died from his injuries.

Following these accidents, the FIA quickly introduced a series of safety reforms.
Beginning in July 1994, F1 cars were required to install a 10 mm-thick Plank beneath the floor. The purpose was to control how low the cars could run during a race.

The original Plank used a high-density wood composite.
Thin layers of beech wood were combined with resin, stacked together, and pressed under high temperature and pressure.

This process created an extremely dense and durable material suitable for the demanding environment underneath a racing car.
The finished material offered approximately half the strength of steel while weighing only about 20% as much as steel.

This combination of strength, durability, and relatively low weight made the material suitable for this unusual motorsport application.
 

The Plank is installed along the centerline beneath the floor, making it one of the areas of the car closest to the track.
As the car runs through a race, contact with the road gradually wears the Plank down.

After the race, officials measure its remaining thickness. If the wear exceeds the permitted limit, it indicates that the car was running too close to the track.
And even a very small difference can change the final result. At the 2025 Las Vegas Grand Prix, McLaren drivers Lando Norris and Oscar Piastri originally finished second and fourth.

Both cars were later disqualified because their Planks had worn beyond the permitted limit.
The minimum thickness measured on Norris's car was 8.88 mm, while Piastri's car measured only 8.74 mm.
In F1, even a difference measured in fractions of a millimeter can determine whether a car passes technical inspection.

As material technology advanced, F1 moved away from the original wood-based Plank toward composite materials made with glass fiber and resin.
These modern materials provide more consistent wear performance and are better suited to the continuous high-speed contact and friction experienced underneath today's racing cars.

The material has changed, but the name “Plank” remains.
There is another interesting connection to its wooden origin.
The 2026 FIA Technical Regulations require the Plank material to have a specific gravity between 1.3 and 1.45—a range that follows the density characteristics of the earlier wood-based Plank.

In other words, wood is no longer the material underneath a modern F1 car, but the characteristics of the original Plank still have a connection to how this component is defined today.

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