After having our roof re-configured and larger overhangs added, I noticed that the contractor placed the bathroom exhaust vent that used to go out the side wall just under the eaves just inside the overhang of the roof. I think they meant for it to vent out through the vent holes in the aluminum soffit material, but I am concerned that instead, moisture will accumulate on the underside of the roof sheathing.
I know I should have the contractor come and fix it, but they have been slow to respond and I would just like to take care of this.
I would like to address this, and I am aware the most proper way would be to go out the roof. But I am not comfortable cutting the hole there and trying to manipulate the shingles to fit a new vent pass-through piece, so instead I would like to set it up like shown in the related question. The vent pipe already terminates underneath the soffit I believe, so I would just need to make a round hole in the soffit material, pull the flexible ducting through, attach the vent piece, and mount it with screws.
I am just not sure what the best way to cut a round hole into the soffit material that is already installed, without taking it down. I am thinking I would mark a template, then drill a small-ish hole in the middle and use tin snips to try to make a round cutout. Alternatively, maybe I could use a Dremel with a cutting wheel. Is there a better way? I am not opposed to buying tools if that's necessary.