We will say this plainly because it would be easy for us not to. Installing waterproof panels solves your shower walls. It does not solve your bathroom's air. Moisture from a hot shower still enters the room, and it still condenses on the ceiling, the mirror, the window frame, the vanity, and the drywall above the panels.

In a climate where outdoor humidity is high for most of the year, ventilation is not a secondary detail. It is the other half of the job, and it is worth doing properly.

Sizing the fan

The standard rule for a bathroom up to about one hundred square feet is one cubic foot per minute of extraction per square foot of floor area, with fifty CFM as the practical minimum. So a seven by eight foot bathroom at fifty-six square feet needs at least a sixty CFM fan.

For larger bathrooms the fixture-based method is better: allow fifty CFM for each toilet, shower, or standard tub, and one hundred CFM for a jetted tub, then add them together. A large primary bathroom with a separate toilet compartment and a big shower can legitimately need one hundred and fifty CFM or more.

In South Florida specifically, size up rather than down. Ambient humidity is already high, so the fan is working against a smaller moisture gradient than the same fan would face in Arizona, which means it needs more capacity to achieve the same result.

The duct matters as much as the fan

A powerful fan on a bad duct run moves very little air. Fan ratings are measured under ideal conditions and real installations rarely resemble them.

  • Use the full duct diameter the fan specifies. Necking a four-inch outlet down to a three-inch duct destroys the airflow.
  • Prefer smooth rigid duct over flexible. Corrugated flex duct has significantly higher friction loss. If flex must be used, pull it taut rather than leaving it slack and sagging.
  • Keep the run short and the bends few. Every elbow is a meaningful loss.
  • Insulate any duct passing through unconditioned space. Warm moist air in an uninsulated duct in a hot attic condenses inside the duct, and that water runs back down into the fan housing and then into your ceiling. This is a common and expensive mistake.
  • Slope the run slightly toward the exterior so any condensate that does form drains outward.

The single most common fault

Vent to the exterior. Not into the attic, not into a soffit, not into a wall cavity.

We find this constantly, including in newer construction. A fan discharging into an attic is not ventilating your bathroom, it is relocating your moisture problem into your roof structure, where it condenses on sheathing and framing. Soffit discharge is nearly as bad, because the soffit is usually a passive intake for attic ventilation, so a substantial share of that humid air is drawn straight back into the attic.

Go and look at yours. It is worth twenty minutes.

Running it properly

Run the fan during the entire shower and for a further fifteen to twenty minutes afterwards. That trailing period is when most of the actual moisture removal happens, because condensation has settled onto surfaces and is re-evaporating.

Nobody reliably remembers to come back and switch a fan off, so automate it. A timer switch is the cheap, reliable option: press it and it runs for a set period. A humidity-sensing switch is better still, since it starts when it detects a rise and runs until humidity returns to a set point, which handles both the forgetting and the guessing.

Choose a quiet one

Fan noise is measured in sones. Below one sone is genuinely quiet; a builder-grade fan is often around three to four sones and sounds like a small aircraft. This is not a comfort nicety, it is the deciding factor in whether the fan actually gets used. A loud fan is a fan that stays off, and a fan that stays off does nothing at all.

Everything else worth doing

  • Leave the door ajar afterwards if privacy allows, so the fan has make-up air to draw. A fan in a sealed room fights against negative pressure and moves far less than its rating.
  • Squeegee or wipe the panels. Removing the water is faster than evaporating it.
  • Keep the shower area from becoming a drying rack. Wet towels left hanging inside the enclosure keep the humidity elevated for hours.
  • Watch the ceiling. It is the coldest surface in the room and therefore where condensation forms first. Persistent spotting on the ceiling above a shower is a ventilation problem announcing itself.
  • Consider whole-house dehumidification if the entire property runs humid. Air conditioning dehumidifies as a side effect, and in shoulder seasons when it runs less, indoor humidity climbs.

Why we raise it

A panel wall genuinely removes the porous joints that cause most shower failures. It does not make the room immune to humidity, and pretending otherwise would set you up to be disappointed by something we could have told you about at the estimate. Michael will look at your fan and your duct during the free measure and tell you if it is inadequate, even though it is not part of the job we are quoting.