The toilets in my house vent to the attic causing a bad smell in a room over the garage.
The room is really a finished part of the attic.

What kind of contractor can I hire to extend the vents through the roof?

Hello Harmonld,

You need to get a plumbing contractor to extend all vents through the roof, and depending on what type of roof you have,( tile, shingles ) you may need a roofing specialist to seal around the vent penetrations , the plumber will be able to give the best advice on what type of roof flashing you will need.good luck-------Zeke
p.s. just curious as to why the vents were not run through the roof?

The toilets in my house vent to the attic causing a bad smell in a room over the garage.
This is not only against every code in the book, but it's also a health hazard . Sewer gas is a health hazard to your families health and the methane content in it makes it explosive. The attic vents will have to be revented back to a single vent that will be run out the roof. DO NOT LET THIS SLIDE! Have it taken care of at once. Good luck, Tom