Just to tell you where I am coming from on this - I wrote the book! (It's fun to say that.) "Residential Ventilation Handbook" It's been said pretty well already, but bath fans must vent all the way to the outside. Not just near an opening. Use insulated ducting to reduce the possibility of condensation in the ducting. Use 3 screws to attach the ducting to the hood. That will keep the ducting from turning or pulling off. Be careful that the screws don't interfere with backdraft dampers. (Cloth duck tape was made from the same duck material sailor's pants were made from. Not good at all for duct work.) If you can do it, transition from the 4" nozzle on the fan to 6" ducting. The flow will be much better. Point the nozzle of the fan in the direction of the exhaust hood. Air is lazy. It hates to make 180 degree turns. Here is a link that might be useful: Heyoka Solutions

I think you might be missing something but you've already pre-judged that roofer so move on and forget about using him. You won't be happy with his work from that pre-judgment. Sounds like he knows 'can' vents won't ventilate properly. So the roof isn't going to last as long. Possibly the manufacture of the material he plans on installing warranties their roofing materials with proper ventilation and most likely specifically spell it out in the installing manuals. If he doesn't meet some kind of minimum spec for the installation .. roofing materials manufacturer will have no warranties on that material, yet he still warranties his otherwise proper installation. I'd speculate,,, He wants competitive feedback so he prices future bids accordingly. Doesn't want to be cheap nor expensive probably. Normal thing for him to seek what his competition charges in competitive markets.

Do you use an overhead hood, over the range microwave, or downdraft ventilation? Overhead hood What hood are you using? Wolf Pro Island Hood around 60 inches long. Captures effluent from 36-inch induction hob cooktop and nearby wok induction hob. What is the style - standard, chimney, canopy pro style or custom wood with insert? See Wolf literature Wall mount, under cabinet or Island mount? Island mount over peninsula What type of blower - internal, remote or inline? External Wolf supplied, Broan/Nutone manufactured. Works with variable control on hood. How many cfms? 1500 nominal at zero static pressure, but probably around a 1000 on max setting at -0.1 inches of house pressure with baffles in place, ducts, and silencer. House calibration has not yet begun. Ducted or Non-ducted? ducted How do the ducts go to the outside? Length, turns,size, thru attic, down into basement? Up a few feet to attic, ~80 degree bend to a Fantech silencer, then some more duct and another ~80 degrees to the roof. Length hasn't been measured, but might be around 20 feet. Do you find it too loud? No Do you have make-up air? A work in progress. MUA will have to dynamically compensate for this hood at any setting, a variable 1000 cfm nominal (probably up to 600 actual) vented filtered diffuser pair over the wall ovens, three bathroom fans, various states of window openings, fireplace, and furnace. If a renovation, then how hard was it to install ducts and how much did it cost? Too difficult to separate out from kitchen ceiling reconstruction, re-insulating the attic, etc. I may not want to know. If a new build then did builder charge you more to duct one way or another? N/A Most importantly, is it effective and work for your needs? Yes.

Of course, this is just speculation on my part but it appears as if the roofer that did the job installed the ridge vent as a dummy ridge vent and didn't intend to have it functioning. I say this because when the owner of the company came here, he expected to just go in the attic and cut away the underlayment. He came back down from the attic after a while and said that he couldn't cut it from inside the attic, it was just too hot up there and he couldn't get to it well enough. Well....I went up there and there are no obstructions keeping him from getting in there and cutting out that plastic...BUT what I did find is that he had cut into the plastic so I looked inside the hole....what I saw was not what I had expected. What I saw was the backside of shingles with only a small opening of about an inch. So not only was the plastic there, the shingles were not installed in a way that you would install them to put on that ridge vent. So he is going to have to take it all off and actually saw out the shingles to make a hole for the air to escape. All the while he kept saying that it isn't even required for there to be a ridge vent over this garage. So I don't know if they were being deceptive or if it really was an oversight. I guess only god knows the answer to that one...HA! But I do know what it looks like. Also, I doubt the company owner knew this because he wouldn't have cut the plastic opened had he known because he had fully intended to just cut it opened.