Technically, elevator ropes (steel wire cables) shrink rather than stretch in cold weather due to thermal contraction. However, changes in temperature and humidity can still significantly impact their performance and perceived tension.

Key Effects of Cold Weather on Elevator Ropes:

Contraction vs. Expansion: Like most metals, the steel in elevator ropes contracts when cold and expands when warm.

Humidity Impact: Seasonal changes in humidity often have a more dramatic effect on rope length than temperature alone. A 30% drop in humidity can cause ropes with a fiber core to shrink by as much as one inch for every 10 floors of a building.

Stiffness and Lubrication: Cold temperatures can make the lubricants on the rope thicker and more viscous, leading to increased wear and a "stiffer" ride.

Brittleness: In extreme cold, steel can become brittle, reducing its ability to absorb shock loads effectively.

Leveling Issues: Because the length of the rope changes slightly with the seasons, the elevator's leveling at floor landings may become inconsistent during winter months.

Why People Think They "Stretch"

While cold causes contraction, elevator ropes do undergo permanent stretch (constructional stretch) throughout their lifespan as the strands settle under load. This is a mechanical process related to use, not a direct result of cold weather.

In Florida, elevator ropes (steel cables) technically shrink rather than stretch during the occasional cold snaps. However, the unique Florida climate creates a specialized set of conditions for elevator maintenance.

1. Thermal Contraction vs. Stretching

   Like most metals, the steel in elevator ropes contracts when cooled. While this is usually minimal, Florida's dramatic swings from daytime heat to nighttime cooling can cause subtle shifts in the elevator shaft that may lead to ride roughness or mechanical wear.

2. The Humidity Factor

   In Florida, humidity often has a more significant impact on rope length than temperature.

   Contraction: A significant drop in relative humidity—common during cold, dry winter fronts—can cause ropes with a fiber core to shrink by as much as one inch for every 10 floors.

   Swelling: Conversely, Florida’s high humidity can cause sisal cores to absorb moisture and swell, which actually increases the rope's diameter and shortens its overall length.

3. Coastal Corrosion Risks

   For buildings near the Florida coast, the combination of temperature changes and salt air is a major concern.

   Condensation: When a rope moves from a humid shaft into a cooler, air-conditioned machine room, condensation can form on the surface.

   Internal Rust: This moisture can wick along the strands, leading to internal corrosion and "rouging" (rust powder), which can eventually cause the rope to fail.

4. Florida-Specific Performance Issues

   Inconsistent Leveling: Because the ropes shrink in the cold and swell in humidity, the car may stop slightly above or below the floor landing during seasonal transitions.

   Lubricant Thickening: In colder months, the lubricants on the rope and rails can become thicker and more viscous, leading to slower operation or unusual grinding noises.

   Machine Room Heat: In summer, Florida machine rooms can easily exceed the recommended 90°F limit, causing electronic malfunctions and motor failures.

   For high-humidity environments like Florida, the most resistant elevator rope cores are synthetic fiber cores and Independent Wire Rope Cores (IWRC).

   Standard natural fiber cores (made from sisal) are hygroscopic, meaning they attract moisture. High humidity causes sisal to swell, which increases the rope's diameter and causes it to shrink in length, potentially leading to leveling issues or premature wear.

Humidity-Resistant Core Types:

Synthetic Fiber Cores (SFC): Often made of polypropylene or other engineered plastics, these cores do not absorb moisture or lubricant. They are more stable in form and diameter during humidity fluctuations compared to natural sisal.

Independent Wire Rope Core (IWRC): This is a full steel core that effectively eliminates moisture absorption issues found in fiber. Ropes with IWRC exhibit significantly less stretch and contraction than fiber cores.

Specialty Synthetic Blends: Branded options like Syncore® utilize synthetic fibers specifically engineered for wet or overly moist conditions, such as outdoor elevators or high-humidity regions.

Key Recommendations for High Humidity:

Galvanized Steel: For maximum protection in coastal or humid areas, specify galvanized steel wires in addition to a synthetic core to prevent corrosion and "rouging" (red rust powder).

Water-Resistant Lubricants: Use specialized water-resistant lubricants that won't be easily displaced by condensation or high humidity.

Regular Maintenance: Even resistant cores require consistent lubrication to seal out moisture and prevent internal friction.