Bathroom Exhaust Fan Installation & Replacement Cost
Replacing a bathroom exhaust fan typically costs $250 – $550 when the duct and wiring are already in place. A new install that needs ducting run to the outside costs $400 – $1,000. The duct must vent outdoors, never into the attic, and that single requirement drives much of the price difference. Here is the full breakdown.
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| Job type | Installed range | What is involved |
|---|---|---|
| Replace an existing fan | $250 – $550 | Same opening, existing duct and wiring reused |
| Replace and upsize the fan | $350 – $650 | Larger CFM unit, possible duct upsizing |
| New install, duct run to outside | $400 – $1,000 | Cut opening, run duct, wall or roof cap |
| Fan with integrated light or heater | $400 – $900 | Extra circuit or wiring for the heater |
| Reroute a duct that vents into the attic | $200 – $600 | Correcting an unsafe existing setup |
| Line item | Typical range | Notes |
|---|---|---|
| The fan unit | $30 – $250 | Basic up to quiet, high-CFM, light-and-heater models |
| Labor (replacement) | $150 – $350 | One to two hours when duct and power exist |
| New duct run | $150 – $500 | Insulated duct from fan to exterior cap |
| Roof or wall vent cap | $75 – $250 | Roof caps and flashing cost more than wall caps |
| New electrical run | $150 – $400 | Only if no power or switch exists at the spot |
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Replace vs new install: the price split
Replacing a fan in an existing opening with a working duct and a wired switch is the $250 – $550 job. The installer removes the old housing, fits the new unit into the same opening, connects the existing duct, and wires it to the existing switch. If the new fan is the same size, the ceiling does not even need patching.
A new install is a different scope. There is no opening, no duct, and sometimes no power. The installer cuts a hole in the ceiling, builds a duct path to the exterior, caps it with a roof or wall vent, and runs wiring if needed. That is the $400 – $1,000 range, and the duct routing is usually the part that moves the number within it.
The venting rule that matters most: never into the attic
A bathroom exhaust fan must vent moist air to the outdoors, through a wall cap, a roof cap, or a dedicated soffit vent. It must never dump into the attic or into a wall cavity. Warm, humid air released into an attic condenses on cold sheathing and framing, and the result is mold, rot, ruined insulation, and sometimes ice dams in winter. This is also why an attic fan is a separate system: it ventilates the attic, it does not receive bathroom exhaust. The same vent-outdoors rule governs a kitchen exhaust fan over the range.
This is one of the most common defects found during home inspections, often because someone installed a fan and left the flexible duct hanging loose in the attic. If your existing fan vents into the attic, rerouting it to a proper exterior cap runs $200 – $600 depending on the path and roof access, and it is worth doing the moment you find it.
- ·Vent to the outside only: wall cap, roof cap, or a dedicated exterior vent.
- ·Never terminate the duct in the attic, soffit return, crawl space, or a wall cavity.
- ·Use the shortest, straightest duct run you can; every elbow cuts airflow.
- ·Insulate duct that runs through unconditioned attic space to stop condensation.
Sizing the fan: CFM and bathroom size
Exhaust fans are rated in CFM, the cubic feet of air moved per minute. The standard rule is roughly 1 CFM per square foot of bathroom floor for rooms up to 100 square feet, so a 50 square foot bathroom wants at least a 50 CFM fan. Larger bathrooms, and any with a separate enclosed toilet or a steam shower, need more capacity and sometimes a second fan.
Noise is rated in sones; a fan at 1.0 sone or less is quiet enough that people actually leave it running, which is the whole point. Quiet, higher-CFM units cost more up front but clear moisture faster, and pairing one with a timer or humidity-sensing switch keeps the room dry without anyone remembering to flip a switch.
Fans with lights, heaters, and humidity sensors
Combination units add features at the housing. A fan-light is a simple step up. A fan with a built-in heater is more involved: heaters draw significant current and frequently need their own dedicated circuit or a heavier wire gauge, which is why those installs land in the $400 – $900 range even as replacements.
Humidity-sensing models and timer switches are inexpensive upgrades that pay off in a drier room and less mold risk. If an electrician is already in the ceiling, swapping in a timer or humidity-sensing light switch is a small line item and a sensible one. The same ceiling access also makes it a convenient time to handle any ceiling fan work elsewhere in the home.
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