Installation Guide

ManualsBrandsGAF ManualsRoof Ridge Vents2028000

INSTALLATION INSTRUCTIONS

ALWAYS REVIEW THESE INSTRUCTIONS BEFORE INSTALLING COBRA

HIP VENT

Important Slope Restrictions: Use only on roofs with slopes between 3:12 and

12:12. Install only on hips. Do NOT install Cobra

Hip Vent on ridges.

Roof Deck: Use minimum

” (10 mm) plywood or oriented strand board (OSB)

decking as recommended by APA-The Engineered Wood Association. Wood decks must

be well-seasoned and supported, having a maximum

” (3 mm) spacing and using

a minimum nominal 1” (25 mm) thick lumber with a maximum 6” (152 mm) width,

having adequate nail-holding capacity and a smooth surface.

Hip Air-Slot Location: To ensure proper exhaust ventilation and weather resistance,

NEVER cut hip air slots below the midpoint of the hip. Do NOT cut air slots less

than 24” (610 mm) in from the building’s warm exterior wall (see Step 2, “Cutting Hip

Air Slots”).

Vent Orientation: ALWAYS install Cobra

Hip Vent with the “Towards Peak”

arrows on the top surface of the vent pointing up towards the peak of the roof. Failing

to do so can result in weather infiltration or leaking.

Ridge Venting: If ridge ventilation will be installed, always install the ridge vent to the

end of the ridge before installing Cobra

Hip Vent to allow for a proper tie-in at the hip

and ridge junction.

STEP 1 – Calculating a Balanced Ventilation System with

Cobra

Hip Vent

Cobra

Hip Vent has 9 square inches of net free ventilating area (NFVA) per lineal foot

(19,051 mm

of NFVA per lineal meter).

To achieve the necessary “balanced” ventilation system with Cobra

Hip Vent, there

must be an air intake system (i.e., soffit, fascia, or undereave vents). For proper venti

lation, the amount of intake ventilation must equal the amount of exhaust ventilation.

A) First, determine the total minimum amount of net free ventilating area

(NFVA) needed for a balanced ventilation system for the entire attic

space, using the following formula:

Sq. ft. of attic floor space

= Total min. sq. ft. of NFVA needed

300

Note: ½ of the NFVA should be provided at the top of the roof (ridge and/or hip

vents) and ½ of the NFVA should be at the bottom of the roof (i.e., soffit, fascia,

or undereave vents). The amount of exhaust ventilation should NEVER exceed the

amount of intake ventilation.

To determine the minimum amount of Cobra

Hip Vent required:

• If a ridge vent is to be installed, first determine how much NFVA will be provided

by the ridge vent.

• To determine how much NFVA must be provided by hip vents, subtract the NFVA to

be provided by the ridge vent from ½ of the total NFVA calculated in Step 1A. If

ridge vents are not used, then the hip vents alone must provide ½ the total NFVA

calculated above.

• Determine the length of Cobra

Hip Vents required:*

sq. ft. (m

) of NFVA hip venting needed x 144/9 (1,000,000/19,051)

= Minimum feet (meters) of Cobra

Hip Vents required

For effective exhaust ventilation and a uniform appearance, install the minimum

required hip ventilation distributed evenly across all hips.

* Note: This calculation does NOT include the additional Cobra

Hip Vent

recommended for installation on the non-vented hip area to achieve the

best appearance. Add the amount of Cobra

Hip Vent needed to cover

the non-vented lower hip area to what is calculated as needed above

to determine the total amount of hip vent you will need to purchase

for your roof.

C) To determine the amount of intake vent required, use the following

formula:

• X = NFVA (sq. in. per lin. ft. [mm

per lin. m]) of the soffit, fascia,

or undereave intake vents

• ½ x (total minimum sq. ft. [m

] of NFVA needed) x 144 / X [1,000,000 / X] =

Minimum lineal feet (lineal meters) of the soffit, fascia, or undereave intake vents

Note: The ventilation calculations above are based on a minimum 1:300

attic ventilation requirement. ALWAYS consult local building codes for attic

ventilation requirements in your area.

STEP 2 – Cutting Hip Air Slots

Cut 2 ½” wide x 36” long (64 mm x 914 mm) SEPARATED hip air slots.

Do NOT cut continuous air slots along the hip areas of the roof. The hip air slots must

be separated 12” (305 mm)

apart

to ensure that the structural integrity of the roof

is not compromised.

Do NOT cut hip air slots BELOW the midpoint of the hip.

Cut one hip air slot 2 ½” x 36” (64 mm x 914 mm) for each of the 4’ (1.2 m) Cobra

Hip Vents sections needed to provide the length of hip venting calculated in Step 1.

For example: if a minimum of ten 4’ (1.2 m) Cobra

Hip Vents must be installed,

cut ten 2 ½” x 36” (64 mm x 914 mm) individual hip air slots as described below.

Hip Midpoint

ck F

ve to

Eave

Ridge

Air Slots

Slot length nearest

midpoint may vary

Deck

Must be at least 24" (610 mm) from the warm wall

NOTE: Cut through sheathing only. Do NOT cut roof trusses, the hip rafters, or any

other rafters.

First Hip Air-Slot/Dimensions: Starting 12” (305 mm) down from the top of the

hip, mark and cut a 2 ½” x 36” (64 mm x 914 mm) air slot centered on the hip to

provide a ½” x 36” (13 mm x 914 mm) opening on each side of the hip rafter. Remove

any sheathing, underlayments, and shingles from the slot.

On plywood or OSB roof decks, where a sheathing seam intersects the hip air slot,

stop cutting the air slot 2” (51 mm) before the seam and continue cutting the slot

2” (51 mm) after the seam, leaving a total of 4” (102 mm) of uncut deck at the seam.

Then, proceed with cutting down to the previously marked 36” (914 mm) point.

HIPVENT

HIPVEN

HIPVENT

Exhaust Vent for Hip Roofs