An unfortunate reality is that we find a lot of people with new roofs that have a disconnected dryer vent.  When a home is re-roofed, it is part of the building code to re-attach the dryer vent to the roof vent so it does not exhaust into the attic.

M1501.1 Outdoor Discharge
The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1504.3. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.

M1502.2 Independent Exhaust Systems
Dryer exhaust systems shall be independent of all other systems and shall convey the moisture to the outdoors.

M1502.3 Duct Termination
Exhaust ducts shall terminate on the outside of the building. Exhaust duct terminations shall be in accordance with the dryer manufacturer’s installation instructions. If the manufacturer’s instructions do not specify a termination location, the exhaust duct shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings. Exhaust duct terminations shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination.
(https://codes.iccsafe.org/content/IRC2015P3/chapter-15-exhaust-systems)

According to the International Association of Certified Home Inspectors, “[…] many dryer vents terminate in crawlspaces or attics where they deposit moisture, which can encourage the growth of mold, wood decay, or other material problems. Sometimes they will terminate just beneath attic ventilators. This is a defective installation. They must terminate at the exterior and away from a door or window.” (https://www.nachi.org/dryer-vent-safety.htm).

When we find this problem, we recommend contacting the municipal or county building official who oversees the roof inspection and contacting the roofing company to come back and fix the roof.  This is because the homeowner already paid for the roof and has a reasonable expectation that it meets code.  From our experience, you should always contact the building official before contacting the roofing company or the probability of getting it fixed is greatly diminished.

in the rare occasion that the roofing company is no longer in business or simply refuses to stand behind their work, which sadly does occur, we will work with homeowners to safeguard the home.  Prices depend on accessibility and the materials required to safeguard the home.

in this situation, the roofers had removed the original gooseneck and detached the top extension of the vent.  The new gooseneck they used didn’t have the metal flashing that The Villages uses to install roofs, so they just left the pipe hanging out.  The roofing company had subcontracted the roof and then after initially trying to deny responsibility, sent someone out to fix it, except despite spending an hour in the attic, never did.  Then, after promising county officials they were addressing the issue, never called the homeowner or responded.

we used an extension to put the termination of the vent into the gooseneck and then used MFM Decktape to seal it in place.

The unfortunate reality is, this can happen with any roofing company, despite their reputation, so it is important to go into your attic after you get a new roof and to visually inspect the dryer vent to make certain it’s attached to the roof, and if it isn’t, to contact the building official who issues the building permit right away.