Building codes such as BOCA, ICBO, SBCCI, and ICC call for installation of a ridge and soffit vent system of attic ventilation to provide 1 square foot of ventilation for every 300 square feet of attic space.

The following calculator will help you determine how much of each type of Benjamin Obdyke ridge ventilation is required for every 300 square feet of attic space.

Step 1:	Enter attic length in feet:		Feet
Step 2:	Enter attic width in feet:		Feet
Step 3:	Calculate

The amount of Benjamin Obdyke ridge ventilation required is listed below:

Roll Vent Standard, Roll Vent Metric or Xtractor X18:		Feet
Rapid Ridge Standard, Rapid Ridge 7, Rapid Ridge Metric or Xtractor XLP:		Feet

Ridge vent systems need to be properly balanced with equal or greater (never less) amounts of soffit ventilation. For this installation you will need to balance with soffit equal or greater than square inches of Net Free Area.

See soffit manufacturers for their ratings and amount you will need to install to meet this requirement.

The above amount is a minimum requirement to meet building codes. In most cases, this will still leave room at the ridge to install more ridge ventilation. To maximize ventilation and provide for best appearance Benjamin Obdyke recommends installation of ridge vent along the entire ridge of the roof. Again, this MUST be accompanied by an equal or greater amount of soffit ventilation. The following will assist you in that calculation.