# Cobra ridge vent problems



## tinner666

The RV is supposed to be an outlet for attic air. It appears to be acting as an intake. Do you have a power fan too?


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## Ed the Roofer

Which version of the Cobra Vent?

Rolled variety or the 3 foot sectional pieces called Snow Country?

*I think Tinner may be on to something.*

Ed


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## dharris008

*Cobra Ridge vent problems*

It is a new construction house with soffit vent at all eaves and no other types of vent other than the cobra vent. The cobra vent is the type that comes in 4' sections and you cap over it with shingles. On the GAF website in the installation diagram it shows a type of screening mesh on the underside but what I have doesn't have this. The spaces between the grills are 1/4" x 1 1/4" wide. This is the only thing that stops bugs and debris from coming in. There is a 1" tall dam on the outside to prevent a blowing rain from coming in but that is it.


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## Ed the Roofer

Either the contractor removed the filter that is laminated to the Cobra Snow Country Ridge Vent, which is my 2nd close runner up choice of ridge vent, or GAF sells a lesser quality version which does not contain the filter.

Air vent has a lesser quality design. The Shingle Vent II is the premier, but they also sell a Venturi Brand Ridge Vent, which does not contain the filter.

I would investigate this more with your roofing contractor who supplied the product for the installation.

The filter is there to inhibit weather breaching the product to the interior of the attic, plus bugs and other organic debris.

Ed


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## dharris008

*Cobra ridge vent problem*

The vent I used is the COBRA III. The website shows a mesh but the distributor say it doesn't. They are bringing in the GAF rep to discuss this further. I will never use this product again due to it's poor design. I am in the south and you can't find the Cobra Snow Country down here. I will start using the AirVent product with the mesh.


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## Ed the Roofer

Oh, are you a Roofing contractor too?

I didn't pick that up from your first post.

Ed


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## 4just1don

*venting requirements for THIS house.*

Just wondered what kind of vent and how many for this SMALL house?? It is 20' wide and 28 foot long. It is perfectly rectangle and has a gable roof with HALF of the front with an eave over hang ,half not and NONE in back. Right now all there is is a small louvered alluminum vent in each end of the gable. This is harsh Nebraska conditions subject to 105 degree summers(or more) and brutal blizzard winters capable of driving snow thru solid brick(well sorta).

have 'heard' ridge vents are prone to snow intrusion 'here' plus no intake from any eave vents cause limited eaves. When reroofing,soon, I was thinking of adding those alluminum roof caps(plastic cant take our occasional HAIL!!) on the south exposure,,how many do I need?? And what gable vent size and type for gable ends??(for use with vinyl siding)(also being installed)

Thanks for helping me calculate this,it isnt my strongest suit!!-d-


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## dharris008

Yes. I have been doing roofing for 20+ years and have never run into this situation before with this product. I don't typically go in the attics after we finish so this may not be an isolated problem.


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## dharris008

4just1don, there is a product called Cor-a-vent X5 which has a flap that shuts the vent off in windy conditions. This will stop driving rain and snow from coming in the ridge vent. I would recommend putting as much ridge vent up as possible and adding as much soffit vent as possible. There are different tupes of soffit vents that can be added to existing soffits. The simplest type would be the round "Plug" vents. All you need to install these is a drill and the proper size hole saw. 4" work better but multiple 2" will also work.


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## Ed the Roofer

I will look up the mini-louvre specs later tonight, but even the 4" diameters offer "Extremely Limited" NFVA.

Is your attic an open air contained area, or a vaulted ceiling?

Static air mushroom style, (Turtle Vents some call them), are nearly impossible to have enough, to provide the right amount of exhaust NFVA.

Ed


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## 4just1don

sorry this was supposed to be a NEW thread. My bad,it took it with a heading,why wont it post as new thread??


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## 4just1don

sorry forgot,normal flat ceilings, roof is about 4/12 or so,,so gets real low on outsides,,,like I said their is ONLY soffits,overhang on a quarter of this house and all on one corner. otherwise zero access from sofit area.

Thought about adding soffits and overhang in process of roofing BUT didnt think it would add any value to this small of house(defined as a forever rental). I LIKE how they protect windows etc,,but added costs would be high compare to just redoing as is. Less cost to soffits of siding job also.


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## dharris008

4just1don, There was a product I used years ago called Hcks Vent. It was a drip edge that had a vent incorporated into it. Pretty cool and very simple to install. It gives you continuous ventilation at the bottom slope of the roof, regardless if you have an overhang or not. I will try to find a link for you. Maybe they can ship it.


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## dharris008

Check out this link. http://www.airvent.com/homeowner/products/intake-ventedDE.shtml


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## Ed the Roofer

That one sucks if you have gutters OR get snow and ice in the winter.

Ed


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## Ed the Roofer

dharris008 said:


> The simplest type would be the round "Plug" vents. All you need to install these is a drill and the proper size hole saw. 4" work better but multiple 2" will also work.


With the Ridge Vent providing 18 square inches of NFVA per lineal foot, you would havwe to match or exceed that quantity from the Intake Vents you use.

A 2 1/4 inch diameter provides only 1.50 square inches per vent plug

A 4 1/2 inch diameter provides only 3.00 square inches per lineal foot.

You would need to install 3 of the 4 1/2 inch diameter plugs every lineal foot of the soffit on both sides of the roof to only equal the amount of the Exhaust NFVA.

What wrong with that picture?

3 x 4 1/2 inches = 13 1/2 inches, plus, that would require them to be one hole right next to each other and you would never get enough in place.

Those specs are from the C-Series Under Eave Cornice Vents, also known as Mini-Louver Vents, from Lomanco.

www.lomanco.com/ProductPAGES/CirkVents.html


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## dharris008

*Soffit ventilation issues*

I understand that plug vents or drip vent may not be the ideal type of ventilation but it is better than doing nothing. As he stated in his previous thread, he only has a small amount of eave and wasn't considering adding eaves to the house. A combination of, simple to install, vents is still better than doing nothing. What would you suggest that is very cost efficient and he will be able to do?


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## Ed the Roofer

Sorry that I did not expand on that last night.

The most practical product to use for continuous Fresh Air Intake Ventilation, is the Smart Vent, by DCI Products Inc.

It is a tapered, shingle over style product which lays on top of the decking, where a 1" slot has been cut out of the decking at the 6" to 7" point from the eave, which then align with the gap in the product, which then allows fresh air to be drawn through the capillary tubes of the coroplast material and then enters into the attic environment.

This provides 9 square inches per foot and when both sides of the house are done with it, then there is an exact balance between intake and exhaust.

An additional plus, is that it will not get clogged from dust and insulation in the attic and will never get painted shut, diminishing its ventilation capacity for intake.

Do a search for Smart Vent on this forum by my User Name. I have been using it for years.

Ed


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## the roofing god

check out "the edge" by Airvent


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## 4just1don

so with the ridge vents and those smart vents or similiar,,,do I close OFF and not use the end gable vents??

Other question,,,how reliable is that flap closing on the cor-a-vent X5 vent?? Do they last as long as a roof?? AND what kind of shingles work these days?? HERE fiberglass shingles dont seal and tend to blow off,,,was told 100 miles south of here they work,here NOT!! Always did the white asphalt in old days,,,was thinking of going with darker color in a asphalt shake kind. Looks good and supposed to LAST longer.(thicker) and heavier

What say you pro roofers??


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## rh55

*Same problem - leaves in attic with Cobra Rigid Vent*

We've got a bunch of leaves in our attic, primarily in the section over the garage. Roof was installed in 2004 using Cobra Rigid Vent II ridge vent. The leaves are small oak leaves (Texas red oaks). I was skeptical this was how they were getting in until yesterday. 

We had a bad hail storm that left a lot of leaves, twigs, and branches (and one dead bird) on my roof. While sweeping the roof, I found a lot of leaves half in to the grate holes (rectangular) in the ridge vents. The wind here is predominantly North-South, and the roof and ridge vent are East-West, so the leaves and dust get blown up the roof until they hit the ridge vent at the peak. I saw this happening as I was sweeping and stirring up dust.

When I googled for Cobra ridge vent leaves in attic, I found three other posts about this happening.

Adjuster is coming next week, and at least one of the roofers (there have been a lot) has said to expect full replacement (the ridge vent was heavily damaged by the golf ball sized hail).

Which leads to a question - what attic ventilation should I think about replacing the Cobra vents with? Ridge vents make intuitive sense to me as far as effectiveness in venting hot air, but I'd like something that will keep leaves out also.


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## Ed the Roofer

Shingle Vent II by Air Vent Corporation is by FAR the best Ridge Vent product on the market.

Ed


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## Diamonds07407

*C0bra snow country*

Hi ed i just read one of your postings that said that you put a 1 1/14 or 1 1/6th space between the sections? I understand the concept which makes sense, but then why doesn't the company have 'instructions' on how to install these? I just saw something that said to butt them together? That contradicts what you said and what happens if you over lap each piece instead of butting them together?
Thanks


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## Ed the Roofer

The installation instructions for installing the Shingle Vent II from Air Vent Corp., do state to leave a slight gap between each section piece of ridge vent.

http://www.airvent.com/pdf/installation/ShingleVentII-install.pdf



*SEE ITEM # 5 IN THE IMPORTANT NOTES SECTION AT THE BOTTOM.*



*ShingleVent II fits roofs with 3/12 to 16/12 pitches.*
*ShingleVent II-7 and II-9 fit roofs with 3/12 to 12/12 pitches.*​ 
*1. *
On existing roofs, remove cap shingles. Mark

slot width at both ends of ridge. Use slot guides
imprinted on vent and refer to drawings below.
Snap chalk line on both sides of ridge.
*4. *​

Pre-fasten first section using roofing nails

through pre-drilled nail bosses. Continue to
pre-fasten remaining sections, making sure
support ribs are flat on the roof and filter is
secure between shingles and vent.
*5. *​

Use utility knife to cut final section to length.

Final section should be oriented so that the integrated
end plug is flush with the end of the roof.
Pre-fasten final section.
*6. *​

Nail cap shingles in place using roofing

nails long enough to penetrate roof sheathing.
Use nailing lines provided on vent as guide. If
using a nail gun, see #8 under important notes.
*2. *​

Cut slot (plumb cut, if possible). _Note: Adjust_

_depth of blade to avoid cutting rafters or trusses._
Refer to drawings below for slot dimensions.
Remove debris from slot.
*3. *​

Center vent over slot. End should be flush

with end of roof. Make sure vent’s support ribs
sit flat on the roof, and that filter is secure
between shingles and vent.
*Hip and Gable Roofs*
Cut slot 3/4" on both sides of ridge centerline
or from ridge board and to within 6" of end
wall or hip intersection as illustrated in
*Figure 4.*
*"L" and "T" Shaped Roofs*
Cut slot, as per ​

*Figure 5 *and run ShingleVent II

across long ridge. On short ridge, cut slot to within
12" of junction point and run ShingleVent II from
end of roof to butt against crossing ShingleVent II.
*Chimneys*
Cut slots to within 12" of chimney. Run
ShingleVent II from end of roof to butt
against chimney as shown in *Figure 6.*
*Highest quality co-polymer *​

remains sturdy,

nailable, and flexible, in all climates.
*Cap shingles install easily*​

, making the vent

virtually invisible.
*External wind baffle *​

creates low

air pressure above the vent and helps
pull air out of the attic.
*Built in end plug *​

seals the end.

*High gloss nailing lines *​

for accurate,

fast cap shingle nailing.
*Nail bosses*​

, reinforced nail holes

designed to prevent over nailing,
located at 16" and 24" centers.
*Air slots *​

have 18 sq. inches (ShingleVent II)

or 16 sq. inches (ShingleVent II-7 and
ShingleVent II-9) free vent area per
lineal foot.
*I N S T R U C T I O N S F O R C U T T I N G S L O T S*
4117 Pinnacle Point Drive
Suite 400, Dallas TX 75211
800-AIR-VENT (247-8368)
(See other side for additional installation instructions)
*I M P O R T A N T N O T E S*
*1. *​

When using standard flat 3 tab shingles, it is unnecessary to caulk under flange of the vent.

*2. *​

Caulk between low areas of shingle and flange of vent, making sure you don’t plug drain holes.

*3. *​

When applying vents to shakes, fold felt as shown in drawings on other side.

*4. *​

Before fastening vent, make sure filter is secured between shingles and vent.​ 


*5. *​

*When installing vent in cold weather, leave a 1/8" gap between vent sections to allow for expansion in hot weather.*​ 


*6. *​

See instructions below for cutting slot.

*7. *​

For best appearance, run ShingleVent II from end to end to give the roof a more even, attractive appearance.

*8. *​

When using a nail gun to install cap shingles over ShingleVent II, special care should be taken. It is important that the roofing

nails penetrate the roof deck without compressing ShingleVent II. Nails driven too deep will dimple or distort the cap shingles.

Nails not driven deep enough may allow ShingleVent II fasteners to back out of the roof deck and could result in blow-offs.​ 


Ed​ 


.​


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## SmittyinDallas

I am a roofing contractor in DFW and this is my third experience with Cobra ridge vent where it's acting as the intake and not as the exhaust. The first one was a new construction garage which we roofed before the brick or siding was installed. It was just a frame. The homeowner contacted me about his new car being dusted with yellow pollen every morning. My site visit showed that the garage contractor (that's all he does) did not install any ventilation intakes in the soffits or either gable. The homeowner would return home, lower the garage door, then exit out the walk-through door. Each time the door was creating suction and drawing in air from through the ridge vent. The homeowner contacted the builder. He steadfastly refused to make the changes - for a customer who'd spent over $20k I thought this to be poor form. We installed an octagonal gable vent that aesthetically coordinated with the main house and it was no longer a problem. 

This customer, whose roof we installed 3 years ago, recently had all new soffits installed and instead of the rectangular grill type every 8' as before it now has the vented James Hardie product, which is continuously perforated for the entire length of the panel. One end of her home, above the garage, is taking in some very small leaves, perhaps the size of a dime, in a pretty significant way. I think the balance of the venting between soffit and ridge vent is part of the problem and the other aspect is her garage door opening and closing and also acting as a vacuum or an intake. I am planning to block a portion of the ridge vent from inside the attic. I have seen the Snow Country ridge vent before as a sample but the distributors here don't stock it. Otherwise, I'll remove the ridge cap shingles and replace a portion of them to offset the difference.

The recent snow event that covered much of the state likely caused some attics with ridge vents to take in snow but homeowners may not have noticed.

Thank you to the previous posters who mentioned alternative products with flaps or other methods of preventing this from occurring.


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