DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Building & Construction (
-   -   Best way to install bathroom exhaust fan (

glehman67 01-23-2011 04:39 PM

Best way to install bathroom exhaust fan
I'm pretty new to home renovations. I have to install a bathroom exhaust fan to assist in controlling possible moisture issues. Does anybody have a advice?



Subcooled 01-23-2011 05:18 PM

Install from attic if possible since this is the easiest access.
Cut your opening in ceiling attach fan to joist tie into electrical. You can tie into existing lighting if you don't want separate switch.

Run exhaust duct to the outside using R-8 or higher to minimize condensation inside the duct.

oh'mike 01-23-2011 05:26 PM

I install these all the time--tell me this--do you have access to the attic above this room?

is this a first floor bath with a no access from above?

Fan only or fan with light?

Fan switched on with light or separate switch?

glehman67 01-23-2011 06:02 PM

Hey gents, thanks for the responses.

There is an attic above the bathroom. I personally can't get access, but I have a slave child that can get in there... kidding.

I'd like to run a separate power to the fan, so I can run it for a while without a light on.

What was meant by the "R-8 or higher" for th duct?

Subcooled 01-23-2011 06:32 PM


Originally Posted by glehman67 (Post 576427)
Hey gents, thanks for the responses.

What was meant by the "R-8 or higher" for th duct?

This is the "R" factor of insulation for the duct. (higher is better) In this case flex duct would be the best to use if installed properly taught with no droops to minimize friction rate and places for condensation to collect.

Most bath fans are 50 to 100 cfm @ .25" static. The fans usually come with a 3" collar. Use an duct increaser from the 3" to 4". 4" will suffice in most applications if under 35' and minimal bends and or elbows while still allowing the fan to exhaust enough air flow (CFM)

For store bought all you will find is flex with a rating no more than R-8. The outside diameter of this due to the insulation will be around 7", so be sure you have the space. Flex duct are also made with microbicide agents to minimize microbes.

Don't use metal duct for this application as it will condense more water and rust over time, harder to install and insulate.

oh'mike 01-23-2011 06:39 PM

Good news---The thing can be installed from above--no drywall patching unless you goof up.

Get a box to put your tools in so you don't loose them into the insulation.

You need--a drywall or keyhole saw---battery drill and a few screws-- spade bit 1 1/2" or bigger

2 bx or romex connectors--14-2 bx or romex--long enough to go from the fan to the switch box.

Some insulated flex duct--a clamp or duct tape.

In a nut shell--find the ideal spot to locate the fan--poke a small hole with a screwdriver--push a wire or coat hanger through the hole so you can locate the spot from the attic.

Get your lackey to climb up there and see if the fan will go where you want it and how you will attach it.---Where the vent will exit (often into the soffit)

Next--wire up the fan---cut and attach the duct to the plastic connector--

Get up there--cut hole --attach fan--get the duct in place--drill hole into top plate of the wall above the existing switch---fish wire into wall with the connector attached (don't forget to remove the nut)

Put insulation back over the work.

Make up the wiring in the switch box---put cover on fan--done--Mike--

glehman67 01-23-2011 06:49 PM

Thanks again gents...

I appreciate all your advice....


oh'mike 01-23-2011 07:11 PM

Have fun--don't fall threw the drywall.:laughing:

rjordan393 01-23-2011 08:16 PM

It may be possible for you to get up into the attic through a nearby closet if you have one on the other side of the bathroom. If you have 2 by 4's holding up your ceiling, then you can only work off a ladder and install a fan within arms reach. However if you use a length of 5/8ths plywood cut to size to fit into your hole, then your weight will be better distributed over a couple 2 by 4's. Thus making it more comfortable to work in the attic. If you have joists in this location, then your weight is no problem. The hole should span wood to wood and the depth should be as wide as needed to fit your shoulders through. If space is limited, you may need to turn your shoulders diagonally to gain access.
After your fan is installed, you can attach moulding on the perimiter of the hole using construction adhesive and then cut a piece of drywall to rest on the moulding. To block air leakage, you can use batt insulation using the same dimensions between the 2 by 4's or joists. This will give you a snug fit. To easily pull the assembly down to rest on the moulding, you can attach two pieces of wood or whatever your imagination can come up with. Follow instructions on the adhesive. you may need 24 hours to cure.
Now for the disclaimer:
Some areas of the country may have differant construction methods and my idea may not be safe. So I ask for the opinions of others.

glehman67 01-24-2011 06:55 AM

rjordan393: Thx for the input. My son has access via his closet. We'll give it a go.

All times are GMT -5. The time now is 05:47 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1