Current building code devotes a considerable amount of instruction designed to improve dryer venting safety. When considering 2010 statistics documented by the National Fire Protection Agency —which found more than 15,000 dryer fires in North American alone—the extra attention is warranted.
While the exhaust system code spans pages, one particular note about screens (highlighted bottom right) is particularly troubling for roof terminations. While screens are regularly included in most other vent caps to protect against pest intrusion, the lint that dryer exhaust carries with it creates lint buildup that other exhaust systems don't face. With the lack of good roof vent options, prior to the introduction of the DryerJack, many savvy contractors would simply remove the screen. While reducing the fire danger clogged screens create, a lack of pest protection also creates problems.Fact Sheet
The images at left clearly show the importance of special treatment for dryer roof vents.
The following code excerpts are actual International Mechanical Code where it addresses exhaust systems for the dryer.
|Dryer Exhaust Duct Fitting Type||Equivalent Length|
|4" radius mitered 45 degree elbow||2 feet 6 inches|
|4" radius mitered 90 degree elbow||5 feet|
|6" radius smooth 45 degree elbow||1 foot|
|6" radius smooth 90 degree elbow||1 foot 9 inches|
|8" radius smooth 45 degree elbow||1 foot|
|8" radius smooth 90 degree elbow||1 foot 7 inches|
|10" radius smooth 45 degree elbow||9 inches|
|10" radius smooth 90 degree elbow||1 foot 6 inches|