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DerbyDad03[_2_] DerbyDad03[_2_] is offline
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Default Ridge Vent or Box Vents?

On 04/10/12 6:38 PM, Home Guy wrote:
DerbyDad03 wrote:

According to them...

Ridge vents need more intake than box vents to operate properly.
With a ~6" soffit, they couldn't put in enough soffit vents to
properly feed a ridge vent. Box vents tend to let more air out
than ridge vents, so in cases like mine, where not enough soffit
vent intake can be provided, they usually recommend box vents
over a ridge vent.


Let's think logically about this. You're being told three things:

A) your current soffit situation is suitable for box vents,
but not for a ridge vent.

B) ridge vents need MORE intake than box vents.

C) box vents let out MORE air than ridge vents.

Look closely at B and C.

Can they both be true statements?

Are these roofers saying that the volume of air going out of the attic
doesn't have to match the air coming into the attic? Because that's the
only way that both A and B can both be true.

If someone determines that you need a certain amount of volume-air-flow
OUT OF your attic, don't let anyone tell you that it can't be done
equally well with either a ridge vent or a suitable number of box
vents. (this is assuming your roof has a long ridge line to begin with
- which any gable-end roof will have).

Now, it's EASY to give your roof enough venting to meet any target
outward air flow. The question is - will it have enough INWARD or
intake air flow capability. If it doesn't have enough intake capacity,
then it won't matter how much outward venting you give it (or what type
of outward venting you have - box vs ridge).

If someone is claiming that box vents can perform some sort of magic and
overcome a deficiency of soffit intake venting, and that a ridge-vent
can't perform this same magic, then get them to explain this magic to
you.


I'm not arguing...I'm discussing.

Earlier in this thread you guys (someone) discussed how different types
of soffit vents allowed for more (or less) air flow in.

I assume the same holds true for box vents vs. ridge vents on the way
out. If ridge vents impede the outflow more than box vents for the same
amount of intake, then could that mean having easier outflow could
overcome less intake vents? Let me explain what I'm thinking...

As an example, let's say I open the glass door on my patio but leave the
screen closed. I also (just slightly) open a window on the other side of
the room. I then use a fan to try and move air out of the door through
the screen. I'll get some intake at the window, but since the outgoing
air is impeded by the screen, the intake will be minimal. If I now open
the screen, I assume I'll have a lot more intact at the window since the
air can move out faster.

So if, as this company seems to be saying, the box vents will let more
air out, more air will be drawn in through the smaller soffits - more
than would be drawn in by the impeded outflow of the ridge vent.
However, with bigger soffit vents, there is more air to be easily drawn
in, so the ridge vents aren't laboring to pull air through them.

I don't know...that's why I'm asking.