Re: dryer vent question
As a recommendation ........ exhaust the dryer through the garage rather than going through the roof.
The reason being .... the ducting would have to penetrate he ceiling of the laundry space then up through the roof deck and every penetration in the roof is a potential place to leak.
Cold winters and snow accumulation you experience in Minnesota are mainly the issue.
The dryer will exhaust very warm and very moist air. With the vent located on the roof all this warm moist air will freeze as well melt snow that will be up there . Enough of this frozen moisture can cause issues similar to " ice damns " where this moisture will make it's way under the surrounding shingles ..... once this melts can cause leaks. Also there is a good chance all this moist air freezing in the winter can erode the fine aggregate covering asphalt shingles and shortens their life. Evidence of this is streaks of discoloration on roofs with bath and dryer vents located on roofs.
The other thing would be all this warm moist air has a likelihood of condensing as it cools along the path up to the roof. The moisture will turn to water and fall back down and depending may cause moisture stains on the ceiling.
Also this moisture will accumulate in the lowest part of the duct which has potential to trap lint allowing it to build up over time causing restrictions.
There is always the annoying issue of the vent itself either freezing shut or open.
Running the exhaust duct horizontally through the garage and venting out a wall would be a better option ..... in my opinion.
Unless the garage is heated space ensure to well insulate the ducting as it will experience the same cooling and condensation conditions.
As for the ducting ..... it's recommended to use rigid metal ducting and if possible try and use the galvanized rather than the thinner aluminum .... the heavier gauge galvanized will last longer and will hold up better from occasional knocks and bumps that may occur being in the garage.
Use the metal foil tape at the connected sections and cover with duct insulation.
Try and keep the 90 degree elbow to a minimum as they add restriction to the air flow. The connection at the dryer is usually a 90 because of it's location .... the fewer and gradual the bends ..... the better for air flow.
The horizontal run in the garage should have a slight slope to it. Where it comes from the laundry room bump out ...... have this end slightly higher and slope it down toward where it exits the exterior wall. The reason is to allow the moisture from the condensation to run out to the outside vent.
Caulk the pipe where it exits the wall ..... also caulk the exterior vent shroud along the top and the 2 sides ..... if you leave the bottom this will allow any water that might get in behind to weep out.
Where this duct penetrates the wall between the garage and the laundry room ...... pickup a can of spray foam to seal the opening around the duct. This will seal any air penetration to help with insulating also preventing any odors and exhaust fumes from the garage entering the living space.
Hopefully this makes sense and helps.
"" an ounce of perception -- a pound of obscure "