I thought about going straight up with it, but I don't have a lot of room due to the angle of the ceiling. Plus, I am going to be using a canopy style hood, so the chase would have to be rather large to be in proportion with the hood, and I'm not sure how that would look. I did think about placing cabinets on top and then a chase above that, but again I am probably too close to the rafters in the attic due to the slope of the ceiling. Consequently, out the wall and into the garage attic seems to be the simplest way to go. Plus, that gets the inline fan away from the house and makes everything more accessible. I don't mind enclosing the vent in drywall to bring it up to code. While the vent needs to be in a soffit, what about the inline blower? It seems like the blower should be left out in the open, with the remainder of the duct enclosed? That said, I can see what you are saying about direct penetrations from the garage into the house are not permitted due to fire concerns. However, would a solid duct running from the kitchen into the garage attic and out the roof fall within that logic? There are no breaks in such a duct run, since the only openings are at the hood itself and wall/roof cap. So as long as the penetration where the duct goes from kitchen to garage is sealed with fire caulking around the duct, how is there an issue? Again, I don't mind enclosing the duct run in a chase if need be, but it seems like overkill....

So I'm replacing my un-insulated vent tubing with insulated because i live in wisconsin and it condenses and drips through ceiling, comes out in low areas at seems of tubing because it goes across attic a distance of 15 - 18 feet on a curve with multiple low spots. I present have a sled under the seem to collect water from last winter tabokkal ! Choice is go up to roof 5-6 feet or out the present vent 15-18 feet with insulated pipe Or shorten the line by going straight to side of home but this requires going up high with latter to drill a new vent hole, as tight quarters in attic prevent drilling from attic. Going to the soffet is 12 feet. I was considering soffet only because I was fearful of too much slow covering my vent. Do I have a legitimate concern as sometimes roof is covered with 10 to 12 inches? My pitch is lower 12-18 I think thats right. Is there a certain vent style or type recommendation? Is there a height that is recommended for safety and efficiency with going up to roof? Thanks for any advice I'll wait patiently

I do not like soffit bath fan vents. My house had one, and you could tell in the attic that the wood was exposed to more moisture there. All of my soffit is the vented aluminum. The window near that exhaust was also more worn. If you exhaust it out of a soffit, it will either wear out a nearby window, the nearby soild soffit, or if the soffit is vented it will go up into the attic. I went through the roof. Get a long feeler drill bit, go into attic, drill bit in appropriate spot, leave bit in and go on roof and you can see where the center of your hole should be. Learn how to install the vent on the shingles, it is similar to the plumbing vent flashings. It is easier to put the flex duct through the hole and attach to vent, then install the vent on the roof.

Happy to help. I've had a bit of this work done myself, in two different houses. In one, I had a Fantech BFRK 100 installed. There was an existing bathroom exhaust fan that worked poorly but I didn't want to put in a new grill. With the BFRK, you take out the guts of the old fan, keep the housing in place, and then connect ducting that runs first to the Fantech unit located a few feet away up in the attic and then from it to the roof passthrough. I had that done by an HVAC contractor who was on site replacing HVAC equipment. I'm not sure they would have done the work otherwise, it was like a favor to me. The second one was the replacement of a 20 year old exhaust fan with light in a WC closet that was noisy and ineffective. I had that done by an electrician who also was doing other work. He needed to go into the attic to remove the old unit, connect the new one to the framing, put in a new duct and connect the power. It made a huge difference. That one also vents through a roof pass-through, important because we use it to vent the bathroom of moisture from showers and baths. Good luck and keep your BS detector handy. If other exhaust vents terminate in the attic, it's time to fix those too. Each duct run needs its own roof passthrough unless you're using a Y setup with one fan at the base of the Y for two locations. Be careful if so, those can be tricky if the duct runs from the rooms to the base of the Y aren't of equal length. As far as duct run distances go, the unit will specify the maximum distance. For my most recent job, the ceiling unit with light that was 110 CFM, I want to say the spec for the duct run was something like 60 feet. I wrestled with putting a wall vent on a gable end but decided to stick with the existing through-roof vent.