need some help with ridge vent + soffit vents

allthumbsdiy

When I replaced my roof 2 years ago, they installed a ridge vent but kept my two 12x20 gable vents (passive), along with 10 circular soffit vents (2" diameter) with foam baffles in between all rafters.

During those two years, I noticed larger than usual ice dams after snow storms and wondered why.

Prior to the new roof, I had installed two layers of insulation (perpendicular) with little to no ice dams.

After reading some posts here and researching the topic, I was prepared to install larger, square soffit vents and close up my two gable vents.

But then, I read the article from airvent.com (http://www.airvent.com/pdf/literature/PAVbooklet.pdf, page 11) which talked about how "a roll vent with an internal baffle does not pull air from the attic" whereas their product which has "an externally baffled vent pulls air from the attic from both sides of the ridge vent".

I have a ridge vent with internal baffles.

Can some pros weigh in as to the legitimacy of this information and what I should do to improve my air flow?

I plan on replacing those small soffit vents either way.

Have you used those "externally baffled" ridged vents? What did your customers say? Would it be fairly easy for a DIYer to remove the existing one and replace it with this one?

Or should I install some gable fans and keep the existing setup?

Thanks.

joecaption

A ridge vent will be short circuted if there's also gable vents. The air is just being sucked in the gables and blown out the ridge, with no draw from the soffit area.

Did you air seal the attic before adding the insulation? (sealing up any holes where plumbing or wiring was run, and over any lighting fixtures?)

Do you now have the roll vent or the plastic, about 3' long vents?

Was there foam or plastic baffles add at the bottom of the roof to make sure the soffits are not block with insulation?

allthumbsdiy

Hi Joe0-

Thanks for your comment. Here are my replies:

Yes, all holes were sealed with Great Stuff and caulking before replacing the first and second layers with new insulation. I plan on peeling back the entire insulation section at a time to seal up small gaps between top plates and sheetrock (not sure how much difference that will make.

I also am thinking about gluing down 2" XPS foam blocks on the top plates for the exterior walls. what do you think?

Roofer used a roll vent. This is same material that was mentioned in the airvent.com article I mentioned earlier which supposedly DO NOT pushes out air from the attic, but tend to draw in air.



This is what airvent is selling (a rigid plastic vent)



I need some validation on this information to make sure that airvent's claim is vendor-neutral (i.e. airvent is not making up this information to push their plastic vent product[/quote]

Yes, foam baffles were installed in the space between each rafters even if that section did not have soffit vents. One thing I neglected to do was check their depth after parts of my roofing deck was replaced so I will be doing that when I check for holes again[/quote]

As stated previously, I intend to replace those small, 2" circle soffit vents with larger rectangle ones but I need to guidance on keeping or replacing my current ridge vent and depending on that decision, what I should do with my gable vents.

Thanks

allthumbsdiy

any comments from roofing pros?

basically I would like to know if "externally baffled" ridge vent is that much superior when compared to rolled ridge vent?

ParagonEx

Yes it is. There are other products that are similar from different manufacturers if you are uncomfortable with air vent however, I highly recommend the shinglevent II

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Windows on Wash

+1

I wouldn't put the Cobra roll out on any home.

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joecaption

My three local shingle distrutors have even stopped selling the roll venting there was so many complants.

allthumbsdiy

Thanks guys.

How difficult is it to remove the existing rolled vent and replace it with the external baffle one?

Any tips or tricks to avoid adding more work?

allthumbsdiy

Any problems with Cobra Ridge Vent made of plastic (http://www.homedepot.com/buy/gaf-cob...2018000.html)?

Ocelaris

The home depot link didn't work... But I got the impression it didn't have the baffle which would lift the air up and over the ridge... It looks like it's just a air permeable foam which you overlay shingles on... so see WOW's post above (could be misconstruing his comments though).

Home Depot Cobra Ridge Vent Link

allthumbsdiy

sorry about that. I grab the link from Google but I now realize that product is not searchable.

I am trying to use up some HD gift cards which is why I am asking about Cobra. BTW, my local store has two versions of Cobra (rolled and plastic).

Ocelaris

I did a quick search on home depot, but didn't see anything like what people were reccomending on their website, but probably more informed people would know better. But it doesn't look like the Cobra roof vent has what people here are reccomending. But I'm not sure if there is an add on piece that could add a baffle?

ParagonEx

That's because shinglevent II is a high quality product.

Go to a local roofing supply company. There is probably an ABC (supply company) near you.

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Gary in WA

The baffles from another source; Mr. Rose, expert in roof ventilation, notice the date- linked from one of our members here, last page; http://paragoninspects.com/pdf/vent/...-myth-rose.pdf

Test for AIR VENT--- but not by: http://www.youtube.com/watch?v=rE6fyWHfTXc

DIY; http://www.ronhungarter.com/ridge_vents.html

More food for thought; http://en.allexperts.com/q/Roofing-1...able-Vents.htm

http://www.finehomebuilding.com/desi...ble-vents.aspx

Gary

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Ocelaris

Ok, so reading those last 2 articles it's implying that you can leave your gables open. I'm basically in the same position as you, house with gables in NJ, and would like to replace the roof and add ridge vents if that's the way to go. So getting ice dams after your improvements isn't too encouraging for me to follow unless it's something else. Increasing your ventilation in the attic without sealing the gaps in the attic floor might draw more warm air up through the gaps to cause ice dams. Take my opinion as a backseat driver, not professional advice...

Did you seal the attic floor with sealant to block heat/air from entering the attic space? What about the area between soffits and top plate ? Not sure if you saw this thread, but look at what this guy/gal did to their soffits, sealing the top plate area.

Good thread on Venting and insulation