# Ridge vent vs standard vent

#1

Hi
Is there a calculation to determine how much ridge venting is equivalent to a standard vent. I’m getting 80ft of ridge and wondering if its enough for a 140 bundle roof.
Thanks!
J.

#2

The code requires 1 sq foot of ventilation per every 150 sq. feet of attic floor space. Most ridge vents supply approx. 20sq inches of ventilation per foot. So you need 7.2 ft. of ridge vent to get 1 sq ft of ventilation. Figure up your attic floor space and use the formula. Your best bet is to have relatively equal amounts of ventilation at your soffit and ridge. If you can achieve this, code allows you to go with 1sq ft. of ventilation per 300 sq. ft. of attic floor space. Continous soffit vent has about 9sq inches of ventilation per foot.

The simple answer to your question is that a ridge vent will almost always provide better ventilation than a standard gable vent. If you have power vents then there is more to talk about.

#3

Shangle Nailer explained that pretty good, except that most ridge vents top out at 18 square inches per lineal foot installed.

Some are way less, like in the 15 to 16 square inch range.

You will get about 1,440 square inches of Exhaust Ventilation from the 80 feet of ridge vent.

You would need 29 regular static air mushroom style pot vents to achieve the same amount of exhaust ventilation, presuming that the interior hole was cut out to the proper size, which they rarely are, so you would need even more.

Ed

#4

Thanks for the replies. Can you have too much ventilation?

#5

Crusmisl,

I am having alittle problem trying to understand you.

You go online and ask for advise from people who you have no idea who they are and what they are about.

If you select a roofing contractor that you can trust, then his word should be all you need.

I don’t mean to offend you or any of the other posters on here.

#6

I trust my roofer I’m just curious and trying to educate myself…

#7

[quote=“ed the roofer”]You will get about 1,440 square inches of Exhaust Ventilation from the 80 feet of ridge vent.

You would need 29 regular static air mushroom style pot vents to achieve the same amount of exhaust ventilation, presuming that the interior hole was cut out to the proper size, which they rarely are, so you would need even more.
Ed[/quote]

Ed, thanks for point this out. Builders almost never get this right, and most roofers don’t know or don’t care enough to educate the homeowners.

I lost a job a while back to a roofer that underpriced me by \$300 on a steep 30-sq 50-year roof. It turned out later that he had put “upgraded” the roof from 2 small static vents to 3. So, this homeowner saved \$300, keeps his high A/C bills, and now has a Zero-year warranty on his 50-year shingles.

#8

[quote=“neville”]

[quote=“ed the roofer”]You will get about 1,440 square inches of Exhaust Ventilation from the 80 feet of ridge vent.

You would need 29 regular static air mushroom style pot vents to achieve the same amount of exhaust ventilation, presuming that the interior hole was cut out to the proper size, which they rarely are, so you would need even more.
Ed[/quote]

Ed, thanks for point this out. Builders almost never get this right, and most roofers don’t know or don’t care enough to educate the homeowners.

I lost a job a while back to a roofer that underpriced me by \$300 on a steep 30-sq 50-year roof. It turned out later that he had put “upgraded” the roof from 2 small static vents to 3. So, this homeowner saved \$300, keeps his high A/C bills, and now has a Zero-year warranty on his 50-year shingles.[/quote]

How much time did you spend with that home owner during the proposal specification presentation?

It seems as if you did not convey the importance of correct ventilation to him and the negative ramifications and consequences of it not conforming to the manufacturers specifications and the local building code.

I applaud you for knowing the difference yourself, but sincerely wish that you could have gotten the homeowner to realize the importance of the proper ventilation as well.

He LOST A LOT of money by thinking that he was saving a few hundred dollars.

Ed

#9

[quote=“ed the roofer”]
How much time did you spend with that home owner during the proposal specification presentation?

It seems as if you did not convey the importance of correct ventilation to him and the negative ramifications and consequences of it not conforming to the manufacturers specifications and the local building code.

I applaud you for knowing the difference yourself, but sincerely wish that you could have gotten the homeowner to realize the importance of the proper ventilation as well.

He LOST A LOT of money by thinking that he was saving a few hundred dollars.

Ed[/quote]

I actually went to great length to make sure he knew all of this info. When he told me on the phone that he had signed with the other company, he actually said that he had concerns about the other guy’s honesty, but that in the end it was all about the money.

#10

That sucks.

But, next time someone calls up, tell them you can be out to their home to meet with them to discuss the questions further in person.

It is much harder for a client to use the cheap excuse when you are looking at them in the face, but more importantly, you get the opportunity to really correct their understanding of which product and service will provide the best value for the dollars being spent.

Ed

#11

Its funny I look around neighborhoods and very, very few homes have ridge venting. Are people really that cheap when it comes to the roof? Actually, when you really look, very few have adequate venting regardless of type.

My roof for example is ~4000sq.ft and I have 6 or 7 vents. Must be homebuilders going as cheap as possible and just barely meeting code. I’m hoping to save on some AC bills this summer.

#12

I suppose I could have pursued it further, but I cannot bring myself to encourage a customer to break a contract, unless they are ignorant of the facts and were defrauded.

Do you think that I’m wrong to look at it that way?