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Roofing/sealing a ridge vent


QUESTION: We recently had our roof replaced.  The roofer suggested we put in a ridge vent although we already had 3 gable vents (one of which opens or closes depending on whether or not the attic fan is on). There's also another electric fan that goes on automatically when it gets too hot up there. We do not have much soffit venting, and he did not add any.
Since the new ridge vent was put in, our house feels suddenly drafty, and the heating bill has gone up tremendously.  After doing some research, I think this is because we don't have adequate soffit venting, and the conditioned air is being pulled out of the residential part of the house and being sucked out the ridge vent. (Our walls, etc. are not super tightly sealed).

When I complained to the roofer, he offered to close up the ridge vent.  Is there a proper way/ best practice for sealing a recently cut ridge vent?  I want to make sure he does it right.

Also, if he was to cut more soffit vents, is that a job that can be easily done wrong?  I'm losing a little faith in him....


ANSWER: Rebecca,

Let me take a moment and apologize for the delay in my response, I had surgery on my ankle Wednesday the 20th so have been a bit out of commission, I am sorry.

Venting is a balancing act between inbound venting and outbound venting.  The Building Code can vary from location to location but as a general rule is basically the same.  To dramatically increase outbound ventilation without increasing inbound venting will create an imbalance and can impact comfort at certain times of the year, especially in colder climates.  In hotter climates, excess outbound venting is usually of little consequence. In colder regions and during the colder months, excess outbound ventilation could keep the attic space colder than normal, hence making the heating system work harder to maintain comfort inside the building.  Ventilation, like the mechanical system as a whole must remain is working balance or it will not perform as designed, too hot or too cold using excess energy to work.

The original modification you made to enhance ventilation should not have made any negative impact, only enhance its effectiveness.  When the ridge venting was added without soffit venting to balance, is likely causing the attic to become too cold as it is moving too much air too quickly from the attic during cold weather months.  My opinion is, you need to make a choice, leave the new ridge venting and balance with added soffit vents or remove ridge venting recently added. In your shoes, I prefer leaving the ridge vent in place and enhance the soffit vent, however, I would insist the roofer engage an engineer to evaluate and determine the square feet of soffit venting needing to be added to balance to Code.  if you elect to remove, he will need to remove the ridge shingles and ridge vent, fill in the wood he removed, install proper felt or ice & water shield to the repaired area, then reinstall ridge shingles.

I hope this give you some usable information to work through this situation.

Steven C. Wadding RRC,RRO,CDT

---------- FOLLOW-UP ----------

QUESTION: Thank you so much for writing back, especially while recovering from surgery.  I hope you are feeling much better by now, and that the surgery was a success.  I'm sorry it's taken so long for me to finally thank you; I got absorbed in another pressing issue and forgot about the roof. Only tonight, when I got back to thinking about the roof, I reread your response and realized that you had not yet been acknowledged for your kindness!  Forgive me, and please accept my heartfelt thanks now.

Picking up where we left off, I am curious if you agree with 2 different suggestions that I have received since I wrote to you and you responded.  

#1 was that, if a ridge vent is to be closed, a thin strip of replacement plywood (to fill in the gap) attached to the joists is not enough support, but in fact a deeper area of about a foot on each side should be cut away from the ridge and then replacement plywood sized about 8 feet by one foot would provide a much better ridge structurally.  What do you think?

#2 was that once the gap produced by the ridge vent is closed, it should be sealed with plyurethane foam to prevent any wet air that still wants to escape from condensing on the underside of the now-closed ridge vent metal (or whatever else might have been used). Do you agree?

Again, thank you so much for your useful information and for volunteering to share it!



I am touched by your sentiments and I am healing, will be a slow process when the cut you foot into pieces and screw it back together.

Question #1 - The once existing gap should have been no more than 1 inch wide on each side of the ridge.  Simply filling in the gap would be satisfactory as there is not structural or point load weight concerns to be overly concerned about. The fill should be of like thickness and a veneer type plywood not OSB, this would be the only real concern.

Question #2 - The voids in the decking here are only of slight greater concern to the others throughout the roof, the plywood joints all vent. My concern with the ridge would be increased water entry in the event a wind storm would compromise the roof system. I would suggest having a 9 inch wide piece of an ice and water type membrane applied to cover the ridge prior to installing the underlayment felt.

Roofing, like other elements of construction have alot of what if's, and many things that may not seem related can actually be related. I say that so when questions arise, you don't feel hesitant to ask questions.  My participation is actually an opportunity to feel a sense of satisfaction helping people that feel a little lost.

Have a great day.

Steven C. Wadding RRC,RRO,CDT


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Steven C. Wadding RRC,RRO,CDT


General questions in regards to most roof types and situations. As the Technical Services Manager for Polyglass USA, Inc. this would not be a forum to address any issues directly related to a product my employer manufacturers.


I have been active in the roofing and waterproofing industries for more than 30 years with extensive experience from product installation, product development and consulting. I have been active in the Construction Specifications Institute and Roof Consultants Institute for approximately 20 years. I am a member of ASTM and am a voting member of various subcommittees. I have many years of consulting experience in the fields of Roofing, Waterproofing and Exterior Building Envelope disciplines.

Roof Consultants Institute Construction Specifications Institute ASTM

Division 7 Technical Binders for Malarkey Roofing Products and Polyglass USA, Inc. CSI Phoenix Chapter Cactus Comments

Registered Roof Consultant - Roof Consultants Institute Registered Roof Observer - Roof Consultants Institute Certifified Document Technologist - Construction Specifications Institute Spray Fireproofing Special Inspector - International Code Council

Awards and Honors
Registered Roof Consultant - Roof Consultants Institute Registered Roof Observer - Roof Consultants Institute Certifified Document Technologist - Construction Specifications Institute Spray Fireproofing Special Inspector - International Code Council

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