Ridge Vent Concern


#1

I recently signed a contract with a roofer that has a great reputation in the area. Checked him out and everyone loves him. My only concern is that I learned they use a ridge product from Benjamin Obdyke called Xtractor Vent XLP for the ridge. They like it because it can be installed by gun, but it only vents at 12.75" per linear foot. I had asked about Shinglevent, and they said they much prefer this product. I am worried about it venting enough air at only 12.75 to sustain the life of my roof.

Will this product be adequate?


#2

As far as “gun nailable” ridgevents go that is probably the best one.
But as you stated it doesn’t provide the venting that most other ridgevents do.
I am guessing that they chose the best product that can be applied quickly.
I can’t really blame them for that…
Let them know that you want a better product, they may want to charge extra for the additional labor.
The additional labor could be anywhere from 1-4 hrs (for 2 men) depending on your house.
Maybe more if it is all steep and cut up etc…
It is a reasonable charge.
I always use shinglevent II, but there are other ridgevents that are just as good.
Another product from Benjamin Obdyke is a 4’ rigid vent that is pretty good, Omni vent.
The better ridgevents are to be applied with 2 1\2" nails minimum, 3" standard.
They cannot be gun nailed.


#3

The answer depends on the entire attic volume space, or floor square footage if you prefer.

Also, for any exhaust ventilation system to function as designed, it need an equal or slightly greater amount of Fresh Air Intake Ventilation.

To determine the necessary amounts of each, you need to supply more information.

Do you have 100 % venting installed on the soffits for the intake ventilationA?

What is the square footage or the dimensions of you home requiring to be ventilated? Make sure to include the length and width of the soffit overhangs.

Is there any attic insulation restricting the air flow from the intake vents to flow fluidly up through to the ridge exhaust ventilation product?

Pull out the tape measure and get back with the results.

Ed


#4

Let me try to hit each of these questions as best I can. House is a single story, 1500 square foot house + 2.5 car garage. Total dimensions roughly: 72’ long by 30’ deep. Eaves hang over 2 feet and only one in every 4 panels is soffeted. They are completely clear to the points I could check, until I got to the cathedral ceiling, where I could also see daylight but could go no further. Insulation is nuwool and it is baffled the entire lenght of the roof. Even in the cathedral portion there is a sizeable gap between roof decking and insulation to allow for airflow.

Hope this info helps!


#5

Honestly i put vents on all the time…We rarely use anything bigger…
I live in Calgaru Canada and we have all kinds of weather…High winds, freezing temprature…everything you can imagine…
I rarely work on reroofs.
I work on homes that are in the millions and we are using out of the box vents…In every box has ten vents…
And these specifications arnte even ours…theses are the builders specifications…

you can eather have something like this which is discreet or have somthing ugly like this…
Honestly i find that if im in a richer neiborhoods we never use anything big and bulky…like this

Honestly the smaller vents do the job very well…and even if you have to replace them the job is alot easier…the cost of the smaller vents vs the big one is huge…
The home builders i work for dont use whirly bird anymore or anything but the samll vent…


#6

Your pics didn’t show up. Are you talking the difference between low profile and high profile ridge vents? To be honest, I would be more concerned about how it performs than how it looks. If the low profile design they use will do a good job and get me 25 years out of a 30-year shingle, then I am good. I just don’t want to be replacing this thing in 10 years.


#7

shiglevent II, snow country, omni ridge.

These are all very good ridgevents choose 1 and sleep well at night.
They all need to be hand nailed with 2 1\2" nails minimum.
As long as your soffits are not plugged up these will all work very well.


#8

I sent an email asking if they will use a handnailed product (preferably Shinglevent II). If I figured it right, which who knows if I did, I have about 8,000 sqaure inches of soffit venting (39 panels of 18x12"). So it can support the improved airflow…


#9

The typical intake soffit vent panels only provide about 50 % of the total calculated square inches.

Check on the Alcoa site or Airvent site and they have perforated and lanced varieties and provide the actual calculated square inches per panel.

I would not listen to the guy who uses the box of 10 mushroom vents because builders specify it. Even on ultra-expensive homes, they usually cut corners on the ventilation.

Based on the dimensions of your home and including the soffit overhang, you would need a total of both intake and exhaust ventilation to be around 17.227 square feet and then translate that to square inches, since that is how the ventilation products are sold, it would bejust over a total of 2,480 square inches needed for the 1/150 requirement.

With 74 feet of Shingle Vent II Ridge Vent, you would get 1,332 square inches of exhaust ventilation. With the brand of ridge vent proposed by your roofing contractor, it would only be 943.5 square inches of exhaust ventilation. Approximately a 30 % decrease in performance.

Ed


#10

[quote]The typical intake soffit vent panels only provide about 50 % of the total calculated square inches.

Check on the alco site or airvent site and they have perforated and lanced varieties and provide the actual calculated square inches per panel.

I would not listen to the guy who uses the box of 10 mushroom vents because builders specify it. Even on ultra-expensive homes, they usually cut corners on the ventilation.

Based on the dimensions of your home and including the soffit overhang, you would need a total of both intake and exhaust ventilation to be around 17.227 square feet and then translate that to square inches, since that is how the ventilation products are sold, it would bejust over a total of 2,480 square inches needed for the 1/150 requirement.

With 74 feet of Shingle Vent II Ridge Vent, you would get 1,332 square inches of exhaust ventilation. With the brand of ridge vent proposed by your roofing contractor, it would only be 943.5 square inches of exhaust ventilation. Approximately a 30 % decrease in performance.

Ed[/quote]

Your da man Ed. :slight_smile:


#11

One thing we can not forget with all that exhaust we should be in the 60% max range for sofit/intake.


#12

[quote=“ed the roofer”]

Also, for any exhaust ventilation system to function as designed, it need an equal or slightly greater amount of Fresh Air Intake Ventilation.

Do you have 100 % venting installed on the soffits for the intake ventilationA?

Ed[/quote]

Axiom,

I did post that earlier, but reinforcing that very and even more critical aspect of the entire “Balanced” Attic Ventilation scenario is always good to be reminded of.

Ed


#13

I love this roofer. No questions asked, he is using Shinglevent II for the ridge at no charge. He said he’d rather have me happy than not, so it is no problem.

I really like these guys.

Thanks again for all the help!


#14

The other thing is with these new home builders the roofs ar pre fabricated…The trusses…
So the homes are very well designed…And in the end it truley depends if you have a open attic or closed off roof…
You have to check what kind of framing your house has and use the proper ventalation…
Some areas of the house may need diffrent tyrp of vents…
The builders house are all new so the whole roof area is one peice…So if you had ten vent holes cut in they can all breath just fine…but if you have areas of the truss that are closed off then i guess youll just have to use the older tyrpe ones…which may look bulky and ugly but all in all the small low profile vents have never given us a problem…not once not twice…never…
and for a box its could go as low a 60 dollars and i personally could install all ten…your houese probally would need ten but i could install a whole box in less than a hour with me cutting the vent holes…
Saves alot of money and it looks nice…
that whats this industry needs for home owners to have propere roofs…Low cost with long term protection…


#15

So, you are thinking that 10 roof vents would be adequate.

I think that you should try to learn to be a better and more learned professional roofing contractor, rather than just a faat and cheap one.

10 RV-50 mushroom vents = 500 square inches of NFVA, until the birds install there nests or the hornets fixate on the underside of the vent.

The Shingle Vent II Ridge Vent would provide 1,332 square inches of NFVA.

Which scenario is the most efficient?

Your 10 mushroom style vent would decrease the exhaust performance by 62.5 % from what the Shingle Vent II Ridge Vent would provide.

Faster and Cheaper does not equate to Better, it just means faster and cheaper. Over 90 % of all residential shingle roofs are not installed according to the Requirements of the Manufacturers Specifications.

You should be comfortable that you are clinging to the majority of either ill informed contractors or ill serving contractors who actually do know what to do, yet still sacrifice quality for production expediency, regardless of the down the road consequences for the roofing systems longetivity.

Ed


#16

Roof buster is a sub contractor that knows nothing about proper installation methods. He only knows what the designer tells him to do. What more can you expect from a sub.

My thing ed is 95% of roofing offits throw out lets say 100 feet of ridge vent using shingle vent 2 lets say equaling 1800 inches of ventilations with 6 soffit vents giving only 336 of intake. The problem lies in the unbalance of exhaust to intake. You have seen this im sure. If any thing should not be in balance it would be more intake.

The 150 rule applys only when soffit vents are not being used/or when there is a reasons you can not stagger them in a position where it would be balanced. Example: i seen a home with i think 10 or so soffit vents that flow 9 inches per foot (alum perf panels)and 3/4 of the front of the house could not have soffit vents and with the low slope porch smart vent was really not an option. Then the 150 rule applies when using exhaust. I will bet the house im talking about is been bid with ridge vent and some slick salesman went and convinced the home owner otherwise. I would like to get the job because of where it is at but hey i want to maintain the warranty of the shingles.


#17

I’m not following, are y’all saying that I don;t have adequate soffit venting? I figure I have ~8400 square inches (39 punched panels @ 12"x18").


#18

if it is a perf panel then it flows 9 inches per foot and if im not mistaken if the panel is perfed the whole way then you will have per vent 19.44 inches flowing from each soffit vent. A total of 758.16 inches of total soffit flow. You have to match that with the exhuast equaling 20.217 feet of ridge vent to have a balanced 50/50 ventilation situation. DOes that help you understand better?


#19

Hmm, I have 93 feet of ridge venting (counting a peak area) per this quote. Is that a good or bad thing? I guess I am confused. Sorry!


#20

That depends on where that extra “Peak” roof is, which I am presuming to be a dormer.

If that ridge line is lower than the main house ridge line AND if the dormer attic area and the main house attic air spaces are connected, then the additional ridge venting may get short circuited.

If the dormer has a vaulted ceiling instead of actually connecting attic spaces, then it is not only okay, but necessary to have BOTH 100 % intake venting and 100 % ridge top exhaust venting.

As GTP mentioned, BALANCE is the key!

The ventilated soffit panels rarely even perforf up to the 9 square inch specifications, once the perforations start to get clogged up from interior dust or cobv webs and in the worst case, if the insulation is blocking or restricting the air flow, which I believe you stated earlier, that you had checked out.

Also, just because you have vented soffit panels does not mean that the carpenter actually cut the hole to the same size as the ENTIRE vented panel.

The best solution is to add additional soffit venting and without having to re-do the aluminum anels, you could have your roofing contractor use a product which allows air intake under the shingles, such a the Smart Vent made by DCI Products Inc.

Ed