How to Install a Bathroom Fan | Ask This Old House

In this video, This Old House host Kevin O'Connor works with a professional electrician to install a ventilation fan in a bathroom. (See below for a shopping list and tools.)

Kevin O'Connor and electrician Brian Bergeron helped a homeowner install a new fan in her bathroom. The fan exhausts the humid air created by the shower to the outside of the house. Brian determined that the easiest way to power the fan was to use the electricity from an existing light switch. With the power shut off, he disconnected the light switch. Next, he enlarged the hole in the wall so he could make the existing electrical box bigger to accommodate a separate switch for the fan. Up in the attic, Brian and Kevin drilled a hole through the top of the wall and "fished" new wire for the fan down to the switch box. Downstairs, Brian connected the wire to the new fan switch, which has a built-in timer. Next, Brian cut a hole in the ceiling between two joists and fastened the fan in place. Then, he connected the new wire to the junction box on the fan. Finally, he cut a hole through an exterior wall and installed a louvered vent on the outside. He then installed flexible ducting between the fan and the wall. Later, up in the loft, Tom recommended that for colder climates, it's a good idea to use insulated ducting to prevent condensation inside the duct.

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Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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How to Install a Bathroom Fan | Ask This Old House

[stacey]

I like how there is always plenty of working room in attics on these projects. My attic is over 10’ in the center but where my fan needed to be we had 5’ clearance 🙄 nothing ends up easy

[bgtheo]

oh. that's it. looks so fkn easy, I'm glad my wife purchased this can't wait to fuk up the install and burn my house down.

[tommiller]

Vent flex pipe should have insulation wrapped around it from fan housing to connection for outside vent. Cold attic and warm moist air going up from the bathroom fan when showering up through the pipe will cause condensation, over time will drip and soak attic insulation will cause mold & mildew over time Also NEVER WRAP REGULAR DUCT TAPE AT CONNECTIONS, USE ALUMIUM TAPE. I also like to use hose clamps after wrapping tape around the connections. DO NOT over tighten hose clamps, just make them snug.

[peppeddu]

You don't need a separate switch/timer for the fan or to cut another hole in the wall.
You can replace the existing switch with one that has also a built-in timer so when you turn on the light the fan automatically comes on and stays on for a number of minutes after you turn off the light.

[Leghar]

"Wow, its so quiet."
Forgets to turn breaker back on.

[TheDIYMoneySaver]

Sent the fish tape down the wall, then came down and pulled the wire from the attic down. Magic

[ronald]

He used sheetrock screws to mount the vent outside. Those screws will rust in no time. It's time people stop using sheetrock screws for everything especially outside.

[Godisknockingx]

Just replaced an old exhaust fan from original build of house from 1969. It had plain old duct tape.
Still working great after about 50yrs on the connections. It did what it needed to do and outlasted the life of the fan. It was still sticky and I think it would last another 50yrs if only the fan would only last as long as the duct tape lol!

[bprotech]

Must use insulated 4" duct to exhaust fan. Also use foil tape instead of duct tape. Duct tape is only good for kidnappings in my opinion. There will be a call-back here when the fan starts dripping condensation.

[bigweiner]

Ducting that runs through the attic should always be insulated to prevent condensation. Rookie move kemosabe

[vlogerhood]

Wrong tape. You should always use aluminum tape for ducts, it doesn't dry up and become useless like duct tape (even "cold rated" duct).

[johnbarone]

The name of this guy's company should be called, "fly by night" handyman services, LOL 😆

[MooseKnuckleWarrior]

Rookie mistakes aside, he should be grateful that he had Wanda with him at the beginning to help locate that metal box 👍 @0:17

[jamesbell]

There were a lot of important steps you missed. For instance, check with your local municipality if you need a permit. Non-permitted work isn't covered by home owners insurance and can make renting/selling tough. 2nd, before cutting the drywall, put something on the floor to collect the dust. Third, blue duct tape instead of foil tape? Fourth, non insulated duct in an attic? Fifth, he totally skipped over the wiring of that box. He bypasses the light switch in the instruction and then shows it magically with the switch at the end, which meant he rewired it off camera... That's a really important part that can cause fires/shorts...

[shawnjasen]

I'm glad this is 9 years ago because this video is full of mistakes that even rookies can see. I hope whole installation got fixed before any major damage occurred.

[kentmccarthy]

In cold climates, an insulated duct should be used.  As installed, moisture will condense in that duct and probably run back into the fan.

[keyboardhec]

attic insulation for the purpose of thermal protection, yes!! Can of great stuff around the seams of that fan for air sealing first! Re apply existing insulation, three and not least insulate duct work to avoid condensation coming back to fan

[codyrae]

@4:59 when he ripped the entire hole out haha messed up bad

[meatycraftfan]

They forgot to put on a insulation sleeve on the pipe Because warm and cold mixed means condensation

[demasofamily]

the decorative cover hahah loved that. you made this look simple. thank you