Cobra® Exhaust Vent For Roof Ridge –
Instruction For Hand Nail Application
Updated: 6/12
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Cobra
Cobra
CobraExhaustVent
ExhaustVent
ExhaustVent
Application
Application
Application
Instructions
Instructions
Instructions
® ®®
For Roof Ridge
Roof
Roof
Deck:
Roof
Deck:
Deck:
Instructions for
Hand Nail Application
Roof Deck:
Use
only
over
well-seamed,
supported
wood
tightly
constructed
with maximum
maximum
lumber,
having
adequate
Use only
Useover
only
Useaa
over
only
well-seamed,
aover
well-seamed,
a well-seamed,
supported
supported
wood
supported
wood
deck,deck,
wood
deck,
tightly
deck,
tightly
constructed
tightly
constructed
constructed
with maximum
with
with
6”
maximum
lumber,
6”6”lumber,
6”
having
lumber,
having
having
adequate
adequate
nail-holding
adequate
nail-holding
nail-holding
capacity.
capacity.
Plywood
capacity.
Plywood
decking
Plywood
decking
as decking
recommended
as recommended
as by
recommended
by the
by
American
thebyAmerican
theWood
Plywood
American
Plywood
Ass’n
Plywood
Ass’n
is acceptable.
Ass’n
isacceptable.
acceptable.
is acceptable.
nail-holding
capacity.
Plywood
decking
as recommended
the
Engineered
Association
is
Slope
Slope
Restrictions:
Slope
Restrictions:
Restrictions:
Useononly
Use
on
only
Use
slopes
on
only
slopes
between
on 2/12
slopes
between
2/12
between
and
2/12
20/12
and
2/1220/12
and 20/12
slopes
between
and
20/12
Slope Restrictions: Use only
A
A A
B
B B
C
C C
D
D D
5
Step
1
1.1.1.
2.Step
2.2. 2
8
5
8
3
4
3.3.Step
3. 3
Instructions
Ridge Vent
Cap
Shingle
Cap Cap
Shingle
Cap
Shingle
Shingle
Instructions
Instructions
Instructions Ridge
Ridge
Vent
Ridge
Vent
Vent
for
Slots...
Installation...
Installation...
Installation...
Installation...
Installation...
foraSlots...
for
for
Slots...
Slots...
Installation...
Installation...
Installation...
®
cap
shingles
directly
over
Cobra
Cut
2” (5.1
cm)
slot long
Uncoil
Cobra® Exhaust Vent
®
®
® Exhaust
InstallInstall
capInstall
shingles
Install
cap shingles
cap
directly
shingles
directly
over
directly
COBRA
over
COBRA
over
EXHAUST
COBRA
EXHAUST
EXHAUST
®
®
®
™™
Cut a Cut
2”
a(2.5
Cut
2” (5.1cm)
acm)
2”
slot(5.1cm)
slot
along
slot
along
Uncoilalong
Uncoil
COBRA
Uncoil
COBRA
COBRA
™
™
ridge,
1”(5.1cm)
onalong
each
side.
the
entire
length
of VENT.
the VENT.
Vent.
Use
Smart
Nails
(supplied)
on
centers
UseVENT.
Smart
Use Smart
Use
NailsSmart
Nails
Nails
(supplied)
(supplied)
on
(supplied)
centers
on centers
on centers
ridge,
ridge,
1”
(2.5cm)
ridge,
1”
(2.5cm)
1”
on
(2.5cm)
each
on
each
on
each
EXHAUST
EXHAUST
EXHAUST
VENT
VENT
along
VENT
along
along
Leave uncut (closed) sheathing
ridge, covering uncut 6” (15.2
recommended
byshingle
shingle
manufacturer.
(Figure
C)
recommended
recommended
recommended
by shingle
by shingle
manufacturer.
by
manufacturer.
manufacturer.
With nail-gun
With With
nail-gun
nail-gun
side. Leave
side.
Leave
uncutLeave
uncut
(closed)
(closed)
(closed)
the entire
the entire
length
the entire
length
of the
length
of theon
of the
area
of
6”side.
(15.2
cm) uncut
at
each
cm)
sheathing
area
both
version,
version,
use
version,
enclosed
use
enclosed
use
gun
enclosed
adapter
gun
adapter
gun
and
adapter
1
and
3/4"
1
and
(4.4cm)
3/4"
1
(4.4cm)
3/4"
(4.4cm)
™
area
ofarea
6” of
area
6”of 6” ridge, ridge,
sheathing
sheathing
sheathing
covering
ridge,
covering
uncut
covering
uncut
6” uncut
6” 6”
Do
not
included
included
coil
included
nails.
coiloverdrive
nails.
coil nails.the Smart Nails .
end
of(15.2cm)
theat(15.2cm)
ridge.
ends.
(Figure
B)
(15.2cm)
eachatend
each
at each
end end (15.2cm)
(15.2cm)
sheathing
(15.2cm)
sheathing
area
sheathing
area area
® C)
(Figure
(Figure
C)
(Figure
C)
Cobra Exhaust Vent Hand Nail Version has
of theof
ridge.
theofridge.
the ridge.
on both
onends.
both
on ends.
both ends.
™
™
3
Cut through the sheathing only,(Figure
Shorter
lengths
can be joined
. Nails
. ™for
. optimum
Do
Not
Do
overdrive
Not
the
overdrive
Smart
the
Smart
Nails
the Smart
Nails
aDo
/overdrive
” (2
cm)
nominal
thickness
4Not
(Figure
B)
(Figure
B)
B)
Cut through
Cut through
Cut
thethrough
sheathing
the sheathing
the sheathing
®
®
®
avoiding
roof
trusses.
(In
houses
by
caulking
and
butting
the
ventilation.
Be
sure
not
to
crush
or
compact
the
Exhaust
Exhaust
Vent
Exhaust
has
Vent
a
3/4"
Vent
has
a
(2cm)
has
3/4"
a
(2cm)
3/4"
normal
(2cm)
normal
thickness
normal
thickness
thickness
Cobra
Cobra
Cobra
only, avoiding
only, only,
avoiding
roof
avoiding
trusses.
roof trusses.
roof
trusses.
Shorter
Shorter
lengths
Shorter
lengths
can
lengths
be
can
be
can
be
with
a(In
ridge
3a1/ridge
(See
Inset
Figure
B) for optimum
2”
product
during
(Figure
for optimum
forventilation.
optimum
ventilation.
ventilation.
Beinstallation.
sure
Benot
sure
Be
tonot
sure
crush
tonot
crush
or toD)crush
or or
(In houses
houses
with
(Inboard,
houses
a3with
ridgecut
awith
ridge
joinedends.
joined
by caulking
joined
by caulking
byand
caulking
and and
(8.9
cm)
cm)(8.9cm)
on buttingbutting
4 (4.4
compact
compact
thecompact
product
the product
the
during
product
during
installation.
during
installation.
installation.
board,
board,
cutslot,
3board,
1/2”
cut1 3/(8.9cm)
cut
1/2”
3 (8.9cm)
1/2”
the butting
ends.
the ends.
the ends.
Nails must be of sufficient length to
(Figure
D)NOTE:
(Figure
D) D)
each
(Figure
A)(4.4cm) (See Inset
slot, 1side.)
slot,
3/4”1slot,
(4.4cm)
3/4”1 (4.4cm)
3/4”
(See Figure
Inset
(See Inset
Figure
B) Figure
B) B) (Figure
penetrate through plywood decks or at least 3/4”
on each
onside.)
each
on each
side.)side.)
into
wood planks.
(Figure
(Figure
A) (Figure
A) A)
NOTE:
underside of the cap shingle before fastening on top of
1. W
hen marking off and cutting slot openings, make sure
® System...
NOTE:
NOTE:
Calculations
forstop
afor
Balanced
aleast
Balanced
a6”Balanced
Ventilation
Ventilation
Ventilation
System...
System...
Cobra
Exhaust Vent. Do not use excess roofing cement
thatNOTE:
theCalculations
endsCalculations
of the
opening
atfor
from
any
end
®
®
®
To walls
achieve
To achieve
To
a “balanced
achieve
a “balanced
a12”
system”
“balanced
system”
with
system”
COBRA
withridge
COBRA
with
EXHAUST
COBRA
EXHAUST
EXHAUST
VENT,
there
VENT,
must
there
there
be
must
ancause
must
be
air an
intake
be
airanintake
system
air intake
system
system
soffits
(i.e.
soffits
(i.e.
or soffits
or or
as
it may
blistering
of(i.e.
the
shingles.
and
at least
from
hip
and
intersections
or VENT,
undereave
undereave
vents).
undereave
vents).
For vents).
proper
For proper
For
ventilation,
proper
ventilation,
ventilation,
the amount
the amount
the
of undereave
amount
of undereave
of ventilation
undereave
must equal
must must
equal
theover
amount
equal
thelaminated
amount
the
of ventilation
amount
ofshingles,
ventilation
of ventilation
at apply
at aat bead
5.ventilation
For ventilation
applications
chimneys.
theW
the ridge.
NOTE:
the
ridge.
NOTE:
In no
NOTE:
In
case
noshould
In
case
no should
case
the
amount
should
the
amount
the
of exhaust
amount
of exhaust
ventilation
of exhaust
ventilation
ventilation
exceed
the exceed
amount
the
amount
the
of intake
amount
of roof
intake
ventilation.
of cement
intake
ventilation.
ventilation.
of exceed
silicone
caulking
or
to the underside of
2.
ridge.
here
short
ridges
(dormers,
ridge
intersections)
are
outer
edge
of
vent
along
the
entire
ridge,
and at
andminimum
cut
and
make
sure
that
theventilation
endventilation
of (NFVA)
• Toused,
determine
• Tomark
determine
• To the
determine
the the
minimum
theslot
square
minimum
square
feet
square
offeet
net
of
free
feet
net
ventilation
offree
net
free
area
area the
(NFVA)
area
needed
(NFVA)
needed
for needed
a balanced
forthe
a for
balanced
aventilation
balanced
ventilation
ventilation
system,
system,
system,
exposed edges so that the gaps are completely filled. Do
thethe
opening
stops
at formula:
leastformula:
12” from the ridge intersection.
use
use
following
the
usefollowing
the
formula:
following
not use excess roof cement as it may cause blistering of
3. Do not install on hip roofs.
the shingles.
4. W
hen installing in high wind areas, apply a bead of
Sq. ft.around
Sq.
of ft.
attic
Sq.ofthe
ft.
floor
attic
of attic
floor
space
floor
space
= Min
space
= Sq.
Min
=ft.
Min
Sq.
of ft.
Sq.
NFVA
offt.NFVA
needed
of NFVA
needed
needed
silicone or roofing cement
perimeter
of
the
300 300 300
®
®
®
• COBRA
• COBRA
•EXHAUST
COBRA
EXHAUST
VENTVENT
has
VENT
16.9
has(hand
16.9
has (hand
16.9
nail)
(hand
and
nail)14.1
nail)
and(nail
14.1
andgun)
(nail
14.1square
(nail
gun) gun)
square
inches
square
inches
of NFVA
inches
of NFVA
per
of NFVA
lineal
per lineal
foot.
per lineal
foot. foot.
Calculations
for
a EXHAUST
Balanced
Ventilation
System...
To determine
To determine
To how
determine
many
how many
how
feet of
many
feet
Cobra
of
feet
Cobra
Ridge
of
Cobra
Ridge
Vent
Ridge
is
Vent
needed,
Vent
is
needed,
use
is
needed,
the
use
following
the
use
following
the
formula:
following
formula:
formula:
®
To achieve
system”
Exhaust
an
intake
system
(i.e.
soffits
or undereave
1/2ax“balanced
(Min.
1/2 x1/2
(Min.
Sq.xft.(Min.
Sq.
of NFVA
ft.Sq.
ofwith
ft.
NFVA
needed)
ofCobra
NFVA
needed)
x 144/16.9
needed)
x 144/16.9
xorVent,
144/16.9
14.1orthere
=14.1
Min.
or must
=
14.1
Min.
lineal
=beMin.
lineal
feetair
lineal
offeet
ridge
of
feet
ridge
vent
of ridge
needed
vent
vent
needed
needed
vents). For proper ventilation, the amount of undereave ventilation must equal the amount of ventilation at the ridge.
• To determine
• To determine
• To the
determine
amount
the amount
the
of undereave
amount
of undereave
of vent
undereave
required,
vent required,
ventuse
required,
theuse
following
the
usefollowing
theformula:
following
formula:
formula:
NOTE: In
case
should
amount
oflin.
exhaust
ventilation
exceed
the
amount
intake
ventilation.
X no
= NFVA
X
= NFVA
X
(Sq.
= NFVA
In.
(Sq.
per.In.
(Sq.
lin.
per.
In.
ft.)
per.
of ft.)
the
lin.of
undereave
ft.)
the
ofundereave
the vent
undereave
orvent
intake
or
vent
intake
vent
or
intake
system
vent of
system
vent
selected
system
selected
selected
1/2 x (Min.
1/2local
x1/2
(Min.
Sq.building
xFt.
(Min.
Sq.
of Ft.
NFVA
Sq.
ofFt.
NFVA
needed)
offorNFVA
needed)
x 144/X
needed)
x 144/X
= Min.
x 144/X
=requirements.
Min.
lineal
= Min.
lineal
feetlineal
offeet
undereave
of
feet
undereave
of undereave
vent needed
vent vent
needed
needed
NOTE: Consult
codes
other
ventilation
• To determine the minimum square feet of net free ventilation area (NFVA) needed for a balanced ventilation system,
use the following formula: Sq. ft. of attic floor space = Min. sq. ft. of NFVA needed
300
© 2003 GAF
© 2003
Materials
©
GAF
2003
Materials
Corporation
GAF Materials
Corporation
06/03
Corporation
06/03 06/03
• Cobra® Exhaust Vent has 16.9 (hand nail) and 14.1 (nail gun) square inches of NFVA per lineal foot.
To determine how many feet of Cobra® Exhaust Vent is needed, use the following formula:
1
/2 x (Min. sq. ft. of NFVA needed) x 144/16.9 or 141.1 = Min. lineal feet of ridge vent needed
• To determine the amount of undereave vent required, use the following formula:
X = NFVA (Sq. in. per lin. ft.) of the undereave vent or intake vent selected
1
/2 x (Min. sq. ft. of NFVA needed) x 144/X = Min. lineal feet of undereave vent needed
©2012 GAF • 6/12 #092