Roof Venting

For dryer efficiency and safety, the shortest and straightest ducting route is always best. Every turn increases friction loss (unless you use non-restrictive elbows). Air velocity reduction from friction loss promotes lint build up and makes the dryer work harder to completely dry each load. Length of run also reduces efficiency. The longer the run, the more friction loss is created which is why building code restricts total run length. Often, going straight up through the roof is the shortest route.