So it seems a project I have this summer is replacing the bathroom fans. The one in the master bathroom makes a lot of racket, and the other one has apparently seized up. The kicker is they both vent into the attic. I'll need to put two vents in to the outside, but what's the best way to cut a 4" hole in the siding?
Cutting a vent in aluminum siding
- Thread starter Dave Sherman
- Start date
Is your soffit also AL? If the soffit is vinyl you could so that with a wood hole saw. If you have to go through the AL, you could do that with a 4" hole saw for metal or tile.
Check your local code as it may have to be a certain distance from your soffits.
Last time I did one, I used one of those roto-zip tools. Looks like a drill bit, but you cut sideways with it. I ran 4" plastic pipe with a 4" elbow out the soffit and into one of those under-soffit mesh/flapper outlets.
My home now has a hole cut through the aluminum siding out the back of the house, with a dryer outlet. Both upstairs bathroom exhaust fans are tee'd into this single outlet, much to my dismay. I can't "see" anything in the attic/crawl space. Everything is buried in blown-in insulation. I keep telling myself to dig into the fans to get replacement part#s so I can swap just the fan/motors some day.
I had to cut through my sheathing and vinyl siding to put the lineset in for my heat pump. I just went at it from inside and cut halfway through the siding to establish the circular pattern. Finished the job from outside. Used an ordinary wood hole saw.
I have no soffit on the rear of the house which is the wall where the bathrooms are; the gutter is right at the edge. I had figured I would have to run the vents to the gable sides of the attic and just run them through the wall.
Consider venting the bathroom exhaust through the roof with a goose-neck vent cap. They are very easy to install if the roof shingles are warm.
^^^^^ this, it should go through the roof IMO.
Just my $0.02
Just my $0.02
Hmm.... It does seem that a roof vent is the preferred way to go on bathroom fan exhausts. No doubt it would be a straight shot up to the roof, it's just the prospect of cutting holes in my roof that gives me the heebie jeebies, probably because I had a couple roof leaks before I had the roof replaced a few years ago. Then again, watching the Home Depot video for installing that it might even be a little easier than trying to go through the siding. Thanks!
Dave, watch the This Old House video attached below. The key is driving the nail through the roof sheathing and shingles from the attic side to give you a point of reference for cutting out the hole. If you try to do that from the top of the roof, you might hit a rafter or mis-position it for the duct hose. Note that they use a 2-piece vent, but the process is essentially the same for a 1-piece vent.
I replaced mine last year. One is on a north facing wall and I wanted a good vent with a good sealing door in it. These have a triple seal and nicely made. Well worth the $. I also used some leftover insulated A/C hose to avoid the condensation in the attic.
