G60 vs G90 Type B Deck: Which Lasts Longer in Florida Humidity?
G90 lasts longer than G60 because it carries more zinc, and zinc is used up gradually as it protects the steel. In Florida's humidity, G60 suits dry, air-conditioned buildings, and G90 is the safer choice for humid interiors, unconditioned spaces and anywhere near the coast. Neither has a fixed lifespan in years. We supply Type B in both.
What humidity does to galvanized deck
Humidity alone corrodes zinc slowly. Problems come from wet time: condensation on the deck underside, roof leaks, wet insulation and water trapped between stacked sheets. Each keeps zinc wet and speeds its loss, and once it is gone, the steel starts to rust.
Choosing G60 or G90
- G60: enclosed, conditioned buildings such as offices and retail with a sound roof.
- G90: warehouses without air conditioning, open structures, canopies, pools, kitchens and process areas.
- G90: any site with salt air.
- Either: install promptly and keep the deck dry until the roof is on.
Extend deck life on site
Store bundles off the ground, sloped and covered with a breathable tarp. Touch up damaged coating. Fix roof leaks early. Tell us the building use and location and we will quote the coating that fits.
Related Questions
Is G90 worth it for an air-conditioned building?
In a dry, conditioned interior, G60 typically performs well, and many specifications allow it. G90 adds margin against leaks and condensation during construction or later. Coastal sites, poorly ventilated spaces and buildings that may sit unconditioned for long periods favor G90. Check your project specification, which may already set the coating.
What is white rust on galvanized deck?
White rust is zinc corrosion product that forms when galvanized sheets stay wet without airflow, usually in tight bundles. Light staining is mostly cosmetic, but heavy buildup means coating loss. Prevent it by storing bundles sloped, raised and covered with breathable material, and installing promptly.