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Ridge Vent or Box Vents?



 
 
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  #51  
Old April 11th 12, 01:22 AM posted to alt.home.repair
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Posts: 193
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.



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  #52  
Old April 11th 12, 01:59 AM posted to alt.home.repair
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Posts: 365
Default Ridge Vent or Box Vents?

On 4/10/2012 7:05 PM, DerbyDad03 wrote:
On 04/09/12 11:52 PM, gonjah wrote:
On 4/9/2012 10:47 PM, gonjah wrote:
On 4/9/2012 7:23 PM, DerbyDad03 wrote:
On 04/09/12 11:51 AM, gonjah wrote:
On 4/8/2012 4:42 PM, DerbyDad03 wrote:
I have heard that ridge vents only work well if there are wide
soffits, like 12" or more.


...Snipped..


Pat: How much are you being charged per vent? What is the soffit
made of?


Oops! Make that DerbyDad.


The price per vent is not broken out. There is an overall price for
the job which includes the soffit and box vents, zinc strips to
control moss, ice/water shield, etc.


Got ya. Thanks
  #53  
Old April 11th 12, 01:59 AM posted to alt.home.repair
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Posts: 196
Default Ridge Vent or Box Vents?


The baffles are up against the roof sheathing, not
the ceiling. If you do the geometry, before they get
to the beginning of the ceiling sheetrock they have
many inches of clearance for insulation. They are
routinely used that way with no problems. It's
precisely what they are designed for.


At the top of my wall I have 3 1/2 inches of height between my roof sheeting
and my wall to provice circulation from my soffits area to my attic. The
baffle is going to use half of that height leaving room for a tiny amount of
insulation.


Might be better to install roof vents just
above the insulation at the bottom of the roof and again at the top. When
you have continuous venting at the soffit and ridge the venting can be
reduced by 50%.


Reduced 50%? As compared to what? With continuous
venting you almost always wind up with more venting
area. And even if you had venting area with continuous
vents that was just equal to that of box vents, why would
it be reduced by 50%?

The mandatory minimum attic ventilation area is 1/150 of the area of the
space ventilated for all enclosed attics or rafter spaces. This minimum can
be decreased to 1/300 if either (i) at least 50% and not more than 80% of
the required ventilation is at least 3 feet above eave or cornice vents with
the balance of the required ventilation provided by eave or cornice vents or
(ii) a Class I or II vapor barrier is installed on the warm-in-winter side
of the ceiling.




  #54  
Old April 11th 12, 12:38 PM posted to alt.home.repair
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Posts: 11,580
Default Ridge Vent or Box Vents?

DerbyDad03 wrote:

He is recommending 10 6" x 16" soffit vents (there are none now) and 6
box vents instead of the current 4.


That's less than 7 sq ft of soffit vents. Assuming a 20% loss for the
screening, you'll have a bit over 5 sq ft of actual vent space.

That should be more than enough for an 800 sq ft house.

Do you live in a single-wide?


  #55  
Old April 11th 12, 02:06 PM posted to alt.home.repair
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Posts: 6,405
Default Ridge Vent or Box Vents?

On Apr 11, 7:38*am, "HeyBub" wrote:
DerbyDad03 wrote:

He is recommending 10 6" x 16" soffit vents (there are none now) and 6
box vents instead of the current 4.


That's less than 7 sq ft of soffit vents. Assuming a 20% loss for the
screening, you'll have a bit over 5 sq ft of actual vent space.

That should be more than enough for an 800 sq ft house.

Do you live in a single-wide?


I agree with you and HomeGuy. This isn't rocket science. You
want adequate intake and adequate exhaust venting. You gave
a formula of 1 sqft vent for every 150 sqft attic space. I've seen
that used before. DD can do some googling to see if there
are other ratios or confirm that one. Whatever amount you need,
you should have something at least close to that. If the soffit
venting is inadequate, the solution is to fix that, not try to
compensate with more exhaust venting.

Let's say it's 85F inside your house and now it's night so
it's 70F outside. To cool it off best, would you:

A - Open 8 windows upstairs and 8 downstairs

B - Open 8 windows upstairs and 4 downstairs.

C - Open 12 windows upstairs and 4 downstairs


The roofers are suggesting C is the solution, even
though from their proposal they don't have enough
box vents on the exhaust to do C. I vote for A.

Also, we've gone through the math on a ridge vent. Because
it's continuous, you get a lot of opening, far more than from
the # of box vents they are proposing. There are a variety of
ridge vent designs. Some allow air to flow more freely than
others. It's possible the roofers just haven't looked at all
that is available and are basing their conclusions on some
crappy design. As far as continuous vents, I'd prefer that
for the soffits as well for the reason that you get more
area and I think they look better.

From aesthetics, what would you rather have? A bunch of
box vents sticking out of the roof, or a ridge vent that isn't very
noticeable?


  #56  
Old April 12th 12, 01:47 PM posted to alt.home.repair
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Posts: 11,580
Default Ridge Vent or Box Vents?

wrote:
On Apr 11, 7:38 am, "HeyBub" wrote:
DerbyDad03 wrote:

He is recommending 10 6" x 16" soffit vents (there are none now)
and 6 box vents instead of the current 4.


That's less than 7 sq ft of soffit vents. Assuming a 20% loss for the
screening, you'll have a bit over 5 sq ft of actual vent space.

That should be more than enough for an 800 sq ft house.

Do you live in a single-wide?


I agree with you and HomeGuy. This isn't rocket science. You
want adequate intake and adequate exhaust venting. You gave
a formula of 1 sqft vent for every 150 sqft attic space. I've seen
that used before. DD can do some googling to see if there
are other ratios or confirm that one. Whatever amount you need,
you should have something at least close to that. If the soffit
venting is inadequate, the solution is to fix that, not try to
compensate with more exhaust venting.

Let's say it's 85F inside your house and now it's night so
it's 70F outside. To cool it off best, would you:

A - Open 8 windows upstairs and 8 downstairs

B - Open 8 windows upstairs and 4 downstairs.

C - Open 12 windows upstairs and 4 downstairs


The roofers are suggesting C is the solution, even
though from their proposal they don't have enough
box vents on the exhaust to do C. I vote for A.

Also, we've gone through the math on a ridge vent. Because
it's continuous, you get a lot of opening, far more than from
the # of box vents they are proposing. There are a variety of
ridge vent designs. Some allow air to flow more freely than
others. It's possible the roofers just haven't looked at all
that is available and are basing their conclusions on some
crappy design. As far as continuous vents, I'd prefer that
for the soffits as well for the reason that you get more
area and I think they look better.

From aesthetics, what would you rather have? A bunch of
box vents sticking out of the roof, or a ridge vent that isn't very
noticeable?



  #58  
Old July 31st 13, 05:44 PM posted to alt.home.repair
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Posts: 1
Default Ridge Vent or Box Vents?

replying to HeyBub , BlueRhyno wrote:
heybub wrote:

Basic rule: You can't have too much soffit vents.
At a minimum, you should have one sq ft of soffit vent for each 150 sq ft

of
floor space. This is one sq ft of unobstructed venting. Some screening
material consumes as much as 2/3rds of the space. Refigure accordingly.
If you have a 1500 sq ft house, you need 100 sq ft of soffits, minimum.
Assuming the screening material is hardware cloth or similar that consumes
less than 20% of the opening, you should plan on 120 sq ft of soffit
venting. Further, assuming small, six inch soffits on a 50 x 30' house,

you
have 160 feet of perimeter. That means only 80 sq ft, maximum, for

available
soffit vents.
Obviously this is woefully insufficient for the appropriate amount of
passive ventilation. You'll have to move up a step in addition to ridge
vents. Turbines are the next step and beyond that powered ventilators.



I'll let you be my banker. I think you slipped an extra "0" in, it should
be 10 sq ft. of soffit.

--
posted from
http://www.homeownershub.com/mainten...ts-691831-.htm
using HomeOwnersHub's Web, RSS and Social Media Interface
to home and garden related groups

  #59  
Old August 1st 13, 03:02 PM posted to alt.home.repair
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Posts: 1,985
Default Ridge Vent or Box Vents?

On 7/31/2013 10:44 AM, BlueRhyno wrote:
replying to HeyBub , BlueRhyno wrote:




I'll let you be my banker. I think you slipped an extra "0" in, it should
be 10 sq ft. of soffit.

--
posted from
http://www.homeownershub.com/mainten...ts-691831-.htm
using HomeOwnersHub's Web, RSS and Social Media Interface
to home and garden related groups


That was already pointed out in the original thread over a year ago.

Another example of idiots posting from homemoanershub.

  #60  
Old August 1st 13, 04:18 PM posted to alt.home.repair
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Posts: 6,405
Default Ridge Vent or Box Vents?

On Tuesday, April 10, 2012 8:05:15 PM UTC-4, DerbyDad03 wrote:
On 04/09/12 11:52 PM, gonjah wrote:

On 4/9/2012 10:47 PM, gonjah wrote:


On 4/9/2012 7:23 PM, DerbyDad03 wrote:


On 04/09/12 11:51 AM, gonjah wrote:


On 4/8/2012 4:42 PM, DerbyDad03 wrote:


I have heard that ridge vents only work well if there are wide


soffits, like 12" or more.




...Snipped..





Pat: How much are you being charged per vent? What is the soffit made of?




Oops! Make that DerbyDad.




The price per vent is not broken out. There is an overall price for the

job which includes the soffit and box vents, zinc strips to control

moss, ice/water shield, etc.




Zinc strips, that's another interesting topic. I just looked into this
a bit myself. There are three camps out the

A - They work great, just put them up at the peak

B - They don't really work at all.

C - They work but only for about 4 ft down the roof.

After looking at a lot of discussion and then looking at some roofs
myself, I think C is probably most accurate. In particular, I saw
an office building here where you could see black mold on most of
the roof, except right below a plumbing vent flashing. The flashing
is apparently galvanized, but the effect was only for about 4 feet or
so down the roof. That section was clear. Below it, the mold resumed.

So, the problems are it looks to me like you have to do it every
4 ft or so to protect it all and having that zinc staged like that
over the roof doesn't look so great. There are also powders that you
can sprinkle on that are supposed to prevent mold for a year or two.
Don't know how well they work.
 




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