Ventilation FAQ's

Our inside sales staff has over 100 combined years of ventilation and construction experience at the disposal of our customers. On difficult or unusual applications, factory assistance and recommendations are readily available. Below are some of most frequently asked questions about our products.

What is the net free vent area of your products?

V-600® product lines have 20 square inches per lineal foot net free vent area (NFVA).
      NOTE:  V-600®T has 20 square inches NFVA when used on both sides of the ridge.
V-300® product line has 13.5 square inches per lineal foot net free vent area (NFVA).
Revolution has 12 square inches per lineal foot net free vent area (NFVA).
S-400 has 10 square inches per lineal foot net free vent area (NFVA).
PS-400 has 10 square inches per lineal foot net free vent area (NFVA).
RS-400 has 18.75 square inches per per piece net free vent area (NFVA).
Roof-2 Wall Vent has 6.75 square inches per lineal foot net free vent area (NFVA).
In-Vent® has 6.75 square inches per lineal foot net free vent area (NFVA).

How many pieces in a carton?

V-600® 11", V-600® 8.5", and all V-300® products have 12 - 4 foot pieces per carton or bundle, enough to do 48 linear feet of ridge.
V-600®T has 24 - 4 foot pieces per carton, enough to do 48 lineal feet of ridge both sides.
S-400 has 24 - 4 foot pieces per carton, enough to do 96 lineal feet of soffit.
PS-400 has 48 - 4 foot pieces per carton, enough to do 192 lineal feet of soffit.
RS-400 has 48 - 221/2" pieces per carton.
Roof-2-Wall Vent has 6 - 4 foot pieces + 25 ft of flashing per carton, enough to do 24 lineal feet.
In-Vent® has 16 - 4 foot pieces per carton, enough to do 64 lineal feet.

What colors does it come in?

S-400 is available in White, Black or Tan. PS-400 & RS-400 are available in White or Black.

What roof pitch can I use your products with?

V-600®, V-600®CS 8.5, V-300®, V-300®CS 8.5, V-300®-7, Roof-2-Wall Vent* and *In-Vent®* can be used with any roof pitch from 3/12 to 16/12. For hip applications minimum over all roof pitch must be at least a 5/12 pitch. (The old style V-400 can only be used with up to a 10/12 pitch roof.)

Which Ridge Vents can I use on a hip roof?

V-600®E and the V-300®E are all recommended to be used with shingles, slate or flat tile on hip roofs. Note: over-all roof pitch should be at least 5/12 and caulking under the vent is recommended. With heavy weight shingles the hip application would be the same as with a slate or flat tile roof. (Click here for PDF detail)

How big of a building can I use your products on?

Cor-A-Vent Ridge Vents are sized for residential and light commercial buildings up to 60 feet wide. Please call Cor-A-Vent before using our ridge vents on buildings wider than 60 feet.

What is the recommended height of the air path?

Cor-A-Vent recommends at least an 1 1/2" to 2" high unrestricted air path between soffit and the ridge. The narrower the air path, the more restriction there will be on the air movement. This will result in loss of efficiency of the vent system.

What size are your ridge vents?

Please open our End View 1 (PDF). It has dimensions for all of our ridge vent products.
Please open our End View 2 (PDF). It has dimensions for our soffit and other ridge vent products.

Does the ridge vent need to be covered?

Yes, the ridge vent should be covered with shingles or a cap of your choice (metal, slate, tile, etc.).

How big of a slot do I need to cut?

The slot should be cut 1 1/2" down from the center of the ridge on both sides. This is the same if you have trusses or a 2X ridge board. Cutting the slot larger will not increase the ventilation and may cause problems with the installation of the ridge vent. If you have a wide ridge beam the vent will have to be split. Either view our Variation Details or call 800-837-8368.

Do I have to have soffit vents?

Yes, the ridge vent must have at least an equal amount of soffit ventilation to balance the airflow. There can be more soffit ventilation, but NEVER less soffit ventilation then ridge ventilation. See our General Installation Instructions for examples of different soffit vent configurations.

Can I use Cor-A-Vent ridge vents with other vents?

The ridge vent should not be used with other roof mounted or gable end vents. They can disrupt the air flow through the attic. A properly setup ridge/soffit vent system does not need to have power roof vents to help move hot air out of the attic. Whole house fans work great with a ridge/soffit vent system. We do not consider them the same thing as the power roof vents.

How do I figure how much ridge vent I need to use?

Take the square footage of house under roof X .48 divide this number by 20 (for V-600® products), or by 13.5 (for V-300® products) this will give the lineal feet of product needed to meet a 1/150 vent ratio. If you are only going for a 1/300 (code minimum) vent ratio divide the above result by two. REMEMBER there MUST be an equal amount of soffit vent (in NFVA) to balance the ridge vent. See our Balanced Ventilation - How it Works FAQ sheet for more information. Our General Installation Instructions also have an example diagram showing the above formula.

Can insects get through the holes?

We have never had any documented evidence that insects got in to an attic through our ridge vent. The size of our openings are the smallest openings recommend by most major building codes for vent openings.

What is the warranty on Cor-A-Vent products?

Our products are guaranteed against defects in material and workmanship for the life of the roofing material that they are used with. To see the complete warranty click here.

What Buying Groups are Cor-A-Vent affiliated with?

Cor-A-Vent is affiliated with; ACE, Do It Best, ENAP, LMC, Orgill and many other buying groups.


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