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Ridge Vent or Box Vents?



 
 
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  #41  
Old April 10th 12, 01:59 PM posted to alt.home.repair
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Posts: 6,405
Default Ridge Vent or Box Vents?

On Apr 9, 9:02*pm, Home Guy wrote:
DerbyDad03 wrote:
The discussion isn't about box vents vs. soffit vents, it's about box
vents vs. a ridge vent.


If you ask me, box vents are more fussy to install (and shingle around)
vs ridge vents, and they don't give you as much ventilation area as you
think. *In your case, the box vents you're being quoted for actually
have a circular opening of about 8" diameter (on the bottom) and the
perforated area on the outer side may not add up to a whole lot of
actual ventilation area.

http://www.lomanco.com/index.php/ven...tic-roof-vents

Your vents have a specified ventilation opening or area of 50 square
inches. *Every running foot of ridge venting will give you between about
24 quare inches ventilation (about an inch worth on two sides) and be
faster to install - but I don't know about the cost of ridge venting.

Your aluminum Lorenco vents come in a box of 6, and can be had for as
little as $20 for a box if this ebay vendor is any example:

http://www.ebay.com/itm/140627349384

Bottom line is that a ridge vent is very easy to install, and gives more
ventilation capability and more even ventilation than box vents.



I agree with the above. I'd seriously doubt the qualifications of
any roofer who gave the story Derby
got.




However, be aware of this:

Summer is notorious for having hot days WITH LITTLE OR NO WIND.

Any passive vent system really needs a good wind to help ventilate your
roof. *So you might (or should) consider not having too much passive
venting AND have some power vent fans.


And I disagree with this. The vent system relies on hot
air rising. Wind will help IF it's blowing in the right direction.
But with the proper amount of passive vents,
for most applications, that's all that's needed.




Going with the lightest-colored shingles you can manage is also better
than dark shingles.


Ads
  #42  
Old April 10th 12, 02:07 PM posted to alt.home.repair
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Posts: 6,405
Default Ridge Vent or Box Vents?

On Apr 9, 11:29*pm, Home Guy wrote:
gonjah wrote:
Should I still be using my attic fan during still periods?
I thought they were not cost effective.


I try to not have my attic temperature exceed 100 degrees F.


100F isn't much in temperature for an attic. Consider that
the attic should already have the thickest insulation in the
house. Maintaining 75F inside with the attic at 100F is
only a temp delta of 25F. Would you be similarly concerned
when the outside temp was 50F during heating season and
the walls, which have less insulation are all exposed?
Of course not, because the temp delta is small enough.






So I'll turn on my attic fan when-ever the temp hits 100, wind or no
wind.

I have a 1500 sf house. How many sf should I have in


soffit vents?


You should have a soffit vent hole between every rafter joist.



Take a look at the post by HeyBub where he goes through the
calcualtion. His target of 1 sqft of vent for every 150 sqft of
attic I've seen used before and seems reasonable.

I'd prefer a continous soffit vent, rather than individual ones.




If you have aluminum soffit, there's no excuse for not having perforated
aluminum soffit along the entire length of the eves. *If you have mostly
(or totally) solid aluminum soffit, take it all down and replace with
100% perforated soffit:

http://www.biytoday.com/Soffit2.jpg

Just cut a hole the size of your hand with a jig saw in the existing
plywood soffit every 16" before you install the perforated soffit.

And remember that anything you do to improve soffit ventilation is
wasted if you have attic insulation jammed into the eves blocking air
flow.


  #43  
Old April 10th 12, 02:15 PM posted to alt.home.repair
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Posts: 1,566
Default Ridge Vent or Box Vents?

gonjah wrote:

You mean you have a fan like this:

http://woodheatstoves.com/images/solarstar_gable.jpg


Yup. It's unplugged and will probably stay that way.


That's probably not a smart thing to be doing in the summer. It will
help reduce the heat in the attic, which will make your house easier to
cool and it will prolong the life of your shingles.

So you don't already have aluminum-clad soffits then... ?


Looks like this w/o all the dirt


(picture)

So you have plywood under your eaves.

If you're not considering putting up aluminum under the eves then you're
probably not going to be doing anything with the eves. If they're high
up off the ground then again it's not so easy to do anything with them.

I wouldn't waste my time putting up more vents under the eaves when it
takes almost as much time and effort to clad the eaves with perforated
aluminum soffits.

The previous owner of my house (build 1976) had clad all outside window
casings and the eves with aluminum. They left the original eave vents
in place and simply covered them with a section of perforated aluminum,
and used solid aluminum everywhere else. I've since replaced half of
the soffits with fully perforated aluminum, and I cut holes in the
plywood between every rafter joist.

I also had to do some repairs to the 1/2" pine boards that close the
eaves (the boards that the gutters are nailed into). So for those roof
sections where I pulled those boards off, I installed down-lights every
4 feet, flood lights and a receptical box at the corners (I also pulled
some low voltage wire and coax to the corners if I want to mount a
camera there). I even installed some speakers every 6 feet.
  #44  
Old April 10th 12, 02:34 PM posted to alt.home.repair
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Posts: 1,566
Default Ridge Vent or Box Vents?

" wrote:

I try to not have my attic temperature exceed 100 degrees F.


100F isn't much in temperature for an attic.


During the hottest 6 weeks of the summer, my attic can reach 100f by
10am. And even with the fan turned on at 10am, the attic will still
climb to 120f by maybe 2 or 3 pm.

My concerns about high attic temperature are evenly split between the
heat-load to the house air conditioner and the impact of the high
temperature to the life of the shingles.

So a few dollars a year of electricity running a couple 1/8 hp motors is
insignificant compared to the perceived benefit in the reduction of
attic temperature during the 2 or 3 months that the fan is used.

Take a look at the post by HeyBub where he goes through the
calcualtion. His target of 1 sqft of vent for every 150 sqft
of attic I've seen used before and seems reasonable.


I feel that the existing formulas are ad-hoc and don't really see any
need for them, especially for new construction (where the eves don't or
won't or shouldn't be sealed on the underside with solid press-board or
plywood anyways).

If you want an even air flow under the roof deck from bottom to top (and
you should want that), the only way you're going to achieve that is by
having either a completely open soffit (open on the underside - no
plywood) and then cover the underside with 100% perforated aluminum - or
put a vent hole every 16" along the entire length of the eaves if you
have a solid wood underside.
  #45  
Old April 10th 12, 02:54 PM posted to alt.home.repair
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Posts: 365
Default Ridge Vent or Box Vents?

On 4/10/2012 8:15 AM, Home Guy wrote:
gonjah wrote:

You mean you have a fan like this:

http://woodheatstoves.com/images/solarstar_gable.jpg

Yup. It's unplugged and will probably stay that way.

That's probably not a smart thing to be doing in the summer. It will
help reduce the heat in the attic, which will make your house easier to
cool and it will prolong the life of your shingles.


The cost of running the fan vs shingles and additional a/c time I
believe is a losing proposition. I could easily be wrong but when they
installed the ridge they said the fan would be, in effect, useless.
Makes sense to me. I doubt it was ever efficient before the ridge vent
because it blows out of a large triangular opening anyway.

My *guess* would be the shingles will go with the next quarter sized
hail storm. Hail is very common here lately.


So you don't already have aluminum-clad soffits then... ?

Looks like this w/o all the dirt

(picture)

So you have plywood under your eaves.

If you're not considering putting up aluminum under the eves then you're
probably not going to be doing anything with the eves. If they're high
up off the ground then again it's not so easy to do anything with them.


Not high but problematic due to the architecture.


I wouldn't waste my time putting up more vents under the eaves when it
takes almost as much time and effort to clad the eaves with perforated
aluminum soffits.

The previous owner of my house (build 1976) had clad all outside window
casings and the eves with aluminum. They left the original eave vents
in place and simply covered them with a section of perforated aluminum,
and used solid aluminum everywhere else. I've since replaced half of
the soffits with fully perforated aluminum, and I cut holes in the
plywood between every rafter joist.

I also had to do some repairs to the 1/2" pine boards that close the
eaves (the boards that the gutters are nailed into). So for those roof
sections where I pulled those boards off, I installed down-lights every
4 feet, flood lights and a receptical box at the corners (I also pulled
some low voltage wire and coax to the corners if I want to mount a
camera there). I even installed some speakers every 6 feet.


You hit some very good points. I'll give it more thought.
  #46  
Old April 10th 12, 03:18 PM posted to alt.home.repair
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Posts: 6,405
Default Ridge Vent or Box Vents?

On Apr 9, 11:04*pm, "Pat" wrote:
The estimate includes:


SOFFIT VENTS
Install ten (10), 6" x 16" size, in client selected color screened soffit
vents in overhangs.


Nowadays 16" or more attic insulation is required by code. *It may be
difficult to prevent the insulation from blocking the air flow from soffit
vents. *If you install baffles to hold the insulation back you may be
putting a flow of cold air next to your ceiling.
*A cold spot on your
ceiling allows mold to grow.



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.


*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%?


*Since you do not have continuous soffit venting a ridge
vent may be undersized by 50%.


Another point that makes no sense to me.
  #47  
Old April 10th 12, 05:38 PM posted to alt.home.repair
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Posts: 8,284
Default Ridge Vent or Box Vents?

On Apr 9, 9:02*pm, Home Guy wrote:
DerbyDad03 wrote:
The discussion isn't about box vents vs. soffit vents, it's about box
vents vs. a ridge vent.


If you ask me, box vents are more fussy to install (and shingle around)
vs ridge vents, and they don't give you as much ventilation area as you
think. *In your case, the box vents you're being quoted for actually
have a circular opening of about 8" diameter (on the bottom) and the
perforated area on the outer side may not add up to a whole lot of
actual ventilation area.

http://www.lomanco.com/index.php/ven...tic-roof-vents

Your vents have a specified ventilation opening or area of 50 square
inches. *Every running foot of ridge venting will give you between about
24 quare inches ventilation (about an inch worth on two sides) and be
faster to install - but I don't know about the cost of ridge venting.

Your aluminum Lorenco vents come in a box of 6, and can be had for as
little as $20 for a box if this ebay vendor is any example:

http://www.ebay.com/itm/140627349384

Bottom line is that a ridge vent is very easy to install, and gives more
ventilation capability and more even ventilation than box vents.

However, be aware of this:

Summer is notorious for having hot days WITH LITTLE OR NO WIND.

Any passive vent system really needs a good wind to help ventilate your
roof. *So you might (or should) consider not having too much passive
venting AND have some power vent fans.

Going with the lightest-colored shingles you can manage is also better
than dark shingles.


I just spoke to another guy from the same company that sent the
estimator out.

Here is what he said, which is more or less in line with what the
estimator said, meaning that the company itself believes this, not
just the guy that looked at my roof.

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.

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

I have appointments with a few more contractors and obviously this
will be a point of discussion.
  #48  
Old April 10th 12, 06:07 PM posted to alt.home.repair
external usenet poster
 
Posts: 365
Default Ridge Vent or Box Vents?

On 4/10/2012 11:38 AM, DerbyDad03 wrote:
On Apr 9, 9:02 pm, Home wrote:
DerbyDad03 wrote:
The discussion isn't about box vents vs. soffit vents, it's about box
vents vs. a ridge vent.

If you ask me, box vents are more fussy to install (and shingle around)
vs ridge vents, and they don't give you as much ventilation area as you
think. In your case, the box vents you're being quoted for actually
have a circular opening of about 8" diameter (on the bottom) and the
perforated area on the outer side may not add up to a whole lot of
actual ventilation area.

http://www.lomanco.com/index.php/ven...tic-roof-vents

Your vents have a specified ventilation opening or area of 50 square
inches. Every running foot of ridge venting will give you between about
24 quare inches ventilation (about an inch worth on two sides) and be
faster to install - but I don't know about the cost of ridge venting.

Your aluminum Lorenco vents come in a box of 6, and can be had for as
little as $20 for a box if this ebay vendor is any example:

http://www.ebay.com/itm/140627349384

Bottom line is that a ridge vent is very easy to install, and gives more
ventilation capability and more even ventilation than box vents.

However, be aware of this:

Summer is notorious for having hot days WITH LITTLE OR NO WIND.

Any passive vent system really needs a good wind to help ventilate your
roof. So you might (or should) consider not having too much passive
venting AND have some power vent fans.

Going with the lightest-colored shingles you can manage is also better
than dark shingles.

I just spoke to another guy from the same company that sent the
estimator out.

Here is what he said, which is more or less in line with what the
estimator said, meaning that the company itself believes this, not
just the guy that looked at my roof.

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.

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

I have appointments with a few more contractors and obviously this
will be a point of discussion.


Keep us up to date please.
  #49  
Old April 10th 12, 11:38 PM posted to alt.home.repair
external usenet poster
 
Posts: 1,566
Default Ridge Vent or Box Vents?

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.
  #50  
Old April 11th 12, 01:05 AM posted to alt.home.repair
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Posts: 193
Default Ridge Vent or Box Vents?

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.

 




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