Bathroom vent ducting

[smorris]

One of the bathroom fans packed it in so we are replacing that one and the master bath with something LOML likes better. Now the problem. somehow I never noticed these were not ducted but just dump into the attic. I want to put in the proper ducting for fans with 3" outlets. Can I use PVC pipe or should I use metal? The run is about 5 feet for one and 12 for the other. Can they use a common duct or will the far one end up venting into the other?

Any ideas would be appreciated, it should be cool enough tomorrow for me to at least get started on it.

[dkhoward]

Your right that dumping the exhaust into the attic is a bad thing. ALl it accomplishes is putting a lot of airborne moisture into the attic space which can cause a multitude of problems.

I have seen the vents plumbed with metal, pvc and abs plastic. MY preference is metal, through the roof with the proper boot and weather cover on the outside.

I would avoid trying to utilize a common vent unless you install good inline backflow dampers and then you have to consider whether you need a bigger through roof vent in the event both fans are operating at the same time.

[Uncle Cracker]

Another option if you hesitate to cut holes in your roof is venting to the eave soffit, or to a dryer vent in a gable.

[lkazista]

I would NOT do a common vent. Separate vents, you gotta get out the drill and buy duct anyway, just drill twice, and buy twice as much. This way you KNOW that each system is independent and there are no issues.

You could use PVC, but flexible metal will go way faster.

Lee

[jaybee]

When we redid the bathroom (from the studs in) and added a small toilet and sink (we call it an en suite ) We put in high throughput straight through the wall vent fan units. The outside part bends the air down along the wall. It was overkill, but even the thought of mildew etc is too much for the boss Works well and required no ductwork.

[Cheeky]

metal will be much easier to install, move and repair, if need be.

insulated is the best.

if you don't have a bathroom fan yet, I highly recommend Panasonic. buy it online, as you will save a pretty penny.

[smorris]

Thanks everybody. 2 ducts it is. I looked around yesterday and the metal duct and a dryer type vent through the soffit are pretty inexpensive. LOML has expanded the project, she wants a light in the fan and it needs to be moved above the shower about 2 feet from where it is now. Make a hole, fix a hole.

[chopnhack]

Ughh...smorris, I feel for you. If I wasnt still doing a thousand things I would come help you! Im not that far from you. Do you have a smooth finish to the ceiling or is it textured? The reason I ask is to refinish the ceiling and have the old hole dissapear may take more work than its worth. Why not just put a recessed light over the shower area and leave the old fan unit in its place?
Have fun!

[jonmulzer]

Thanks everybody. 2 ducts it is. I looked around yesterday and the metal duct and a dryer type vent through the soffit are pretty inexpensive. LOML has expanded the project, she wants a light in the fan and it needs to be moved above the shower about 2 feet from where it is now. Make a hole, fix a hole.

I feel for ya. When we were repainting the bathroom I decided to take out the medicine cabinet to make it easier to patch holes and sand. The gf came in and remarked how she liked it better without the cabinet and she had "the cutest little mirror that would look better." So then I am off to the BORG for a piece of drywall to patch the hole.

[eezlock]

bathroom vent ducting

Better to have the 3" metal ducting from each unit to the outside and not
tied together in any way. Just having the vents dump into the attic space
is not good for several reasons, one of them is the moisture build up in the
attic that can and does lead to mold/ mildew build up. eezlock

[mpauly]

You'll be pumping warm, moist air through that piping, if it's going to pass through a cold attic you should really use insulated pipe. If you don't that air will likely condense and lead to rot/mold/etc.

[Cheeky]

You'll be pumping warm, moist air through that piping, if it's going to pass through a cold attic you should really use insulated pipe. If you don't that air will likely condense and lead to rot/mold/etc.

looks like he's in tampa, so most likely will be exhausting AC cooled air through a hot attic. insulated is a fine idea.