Intake Vent Clearance

How much clearance (height) does your roof air intake vent need?

The answer depends on
1) The climate zone you live in
2) The slope of your roof (how pitched or how flat)
3) The placement of the roof vent on the roof (is the roof vent on the upper or lower portion of the roof)

These applications are for when Air Intake Vents are installed on the lower portion of the roof. For asphalt shingle roofs in climates zones 4 and higher, a snow guards / rain diverters should be installed above the vent. This will protect the roof vents from sliding ice and rushing water.

Snow guards / rain diverters are not needed when a roof pitch is 2/12 or less. 

When intake roof vents are installed on the lower portion  of a roof (above the gutter) and the roof pitch is 3/12 or higher you will need:

  • 4″ tall collar for zones 1, 2 & 3 as long as you also install a rain diverter above the roof vent.
  • 6″ tall collar for zone 4. A snow guard is highly recommended.
  • 8″ tall collar for zones 5 & 6. A snow guard is required.
  • 11″ or 12″ tall collar for zones 7 & 8. A snow guard is required.

You can always use taller collars for additional clearance in warmer zones, but you can’t use shorter collars in colder zones. Additionally, you can have your vents extra tall, custom collar heights are available.

Click here to find the zone of your county.

Source: US Office Of Energy Efficiency & Renewable Energy
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