(Sorry about the last blank post, which was an accident.) Anyway, my
problem is there is mold growing in my attic, primarily on the ceiling,
underneath the roof sheathing, and mostly on the side of the attic in which
the roof is facing the north. I'm looking into getting the mold cleaned up,
but it seems to me I need to have the ventilation issue taken care of first.
A roofer looked at my roof, and doesn't think there are any active leaks.
My roof is less than 9 years old.

My attic is a crawl space that is around 1000 square feet in size, and I'm
guessing that it's maybe about 4 feet high at the center. There are two
gable vents; one on the east side and one on the west side. There are two
passive square vents near the ridge of the roof. There is almost no
ventilation at the soffits, that is, my attic does not have soffit vents,
and, although there are a couple of little places where I can see daylight
near the eaves, this doesn't amount to much.

A roofer is talking about installing another roof vent with a temperature
controlled fan near the center of the roof near the ridge. I'm just
wondering if doing so would be helpful, or would it turn out to be no help,
or problematic? My fear is that the fan might just draw air inward from
the two closest vents, which are the existing square passive roof vents. Am
I incorrect in suspecting this could happen?

My understanding, is that the consensus on the internet is that the state of
the art in attic ventilation is to have continuous soffit vents with a
continuous ridge vents. Since my attic currently already has two gable
vents, plus two square passive roof vents. I'm just wondering if switching
to the ridge/soffit system would be the only real solution to my attic mold
problem, or if there would be a way to improve upon my existing ventilation
system (such as a installing fan). Any ideas. Basically I need to ensure
that whatever I have done ventilation-wise is going to be a real improvement
which results in mitigating the chances of mold growth. Any
recommendations?

Thanks.

Jeff

jeff wrote:

(Sorry about the last blank post, which was an accident.) Anyway, my
problem is there is mold growing in my attic, primarily on the ceiling,
underneath the roof sheathing, and mostly on the side of the attic in which
the roof is facing the north. I'm looking into getting the mold cleaned up,
but it seems to me I need to have the ventilation issue taken care of first.
A roofer looked at my roof, and doesn't think there are any active leaks.
My roof is less than 9 years old.

My attic is a crawl space that is around 1000 square feet in size, and I'm
guessing that it's maybe about 4 feet high at the center. There are two
gable vents; one on the east side and one on the west side. There are two
passive square vents near the ridge of the roof. There is almost no
ventilation at the soffits, that is, my attic does not have soffit vents,
and, although there are a couple of little places where I can see daylight
near the eaves, this doesn't amount to much.

A roofer is talking about installing another roof vent with a temperature
controlled fan near the center of the roof near the ridge. I'm just
wondering if doing so would be helpful, or would it turn out to be no help,
or problematic? My fear is that the fan might just draw air inward from
the two closest vents, which are the existing square passive roof vents. Am
I incorrect in suspecting this could happen?

My understanding, is that the consensus on the internet is that the state of
the art in attic ventilation is to have continuous soffit vents with a
continuous ridge vents. Since my attic currently already has two gable
vents, plus two square passive roof vents. I'm just wondering if switching
to the ridge/soffit system would be the only real solution to my attic mold
problem, or if there would be a way to improve upon my existing ventilation
system (such as a installing fan). Any ideas. Basically I need to ensure
that whatever I have done ventilation-wise is going to be a real improvement
which results in mitigating the chances of mold growth. Any
recommendations?

Thanks.

Jeff

Gable vents and roof vent send the air where it's *not* needed;
the air bypasses the problem areas-the roof sheathing between rafters.

http://www.ronhungarter.com/ventilation_repairs.html

Jim

Hi Jim,

Thanks for the reply. Yes, I'm already aware that a continuous ridge/soffit
system is considered to be the state of the art. However, since my attic
already has two square passive vents near the ridge, I'm wondering if there
might be another satisfactory, yet cost effective, solution to my attic mold
problem than simply closing off all 4 of my existing vents and altogether
switching to a continuous ridge/soffit system.

My attic is 1000 square feet of crawl space. Suppose I were to have a roofer
add, say 2 or 3 additional square passive vents near the ridge. My roof
would then have a serious of, say, 4 or 5 square passive vents near the
ridge rather than having only 2 square vents near the ridge. Now suppose I
also had the roofer add soffit vents, and I were to close off the two
existing gable vents. Would having soffit vents plus a series of square
passive vents near the ridge function almost as well as a continuous
ridge/soffit system, or do you think my only valid option is to have a
contuous ridge vent installed?

Is there a way temperature or humidity-controlled fan-power vent could be
utilized to enhance my existing system, or should I stay away from a
fan-powered vent altogether.

Again, is my only valid option to have a contuous ridge/soffit system
installed or are there any other satisfactory yet cost effective solutions
(such as a series of passive square roof vents near the ridge combines with
soffit vents)? My attic is roughly 35 feet long by 28.5 feet wide. If a
series of square passive roof vents near the ridge would work well in
conjunction with soffit vents, then how many 9" vents would you recommend I
get installed?

Thank you, or anyone else for your advice. Just out of curiousity, is there
anyone out there who disagrees with the idea that my gable vents must be
closed off altogether in favor of a ridge/soffit system?

Jeff

From: "jeff"


Hi Jim,

Thanks for the reply. Yes, I'm already aware that a continuous ridge/soffit
system is considered to be the state of the art. However, since my attic
already has two square passive vents near the ridge, I'm wondering if there
might be another satisfactory, yet cost effective, solution to my attic mold
problem than simply closing off all 4 of my existing vents and altogether
switching to a continuous ridge/soffit system.

My attic is 1000 square feet of crawl space. Suppose I were to have a roofer
add, say 2 or 3 additional square passive vents near the ridge. My roof
would then have a serious of, say, 4 or 5 square passive vents near the
ridge rather than having only 2 square vents near the ridge. Now suppose I
also had the roofer add soffit vents, and I were to close off the two
existing gable vents. Would having soffit vents plus a series of square
passive vents near the ridge function almost as well as a continuous
ridge/soffit system, or do you think my only valid option is to have a
contuous ridge vent installed?

Is there a way temperature or humidity-controlled fan-power vent could be
utilized to enhance my existing system, or should I stay away from a
fan-powered vent altogether.

Again, is my only valid option to have a contuous ridge/soffit system
installed or are there any other satisfactory yet cost effective solutions
(such as a series of passive square roof vents near the ridge combines with
soffit vents)? My attic is roughly 35 feet long by 28.5 feet wide. If a
series of square passive roof vents near the ridge would work well in
conjunction with soffit vents, then how many 9" vents would you recommend I
get installed?

Thank you, or anyone else for your advice. Just out of curiousity, is there
anyone out there who disagrees with the idea that my gable vents must be
closed off altogether in favor of a ridge/soffit system?

Jeff

How the moist air escapes isn't an issue here as long as there are sufficient
means for that to occur. Your problem is how to introduce fresh air where it's
needed, which is down near the soffit areas. A continuious soffit vent is
ideal, but those 2" round discs work well too.

A powered gable vent does nothing but suck air in from the ridge if both types
of vents coexist.

A powered gable vent does nothing but suck air in from the ridge if both
types
of vents coexist.

Well, the roofer is talking about adding a powered vent near the ridge, not
at a gable end. However, since there are already two passive roof vents
near the ridge, my fear is that the fan would likely cause the two passive
roof vents to suck air in and short circuit the benefit of the fan.

I'm thinking about having soft vents installed plus additional passive roof
vents near the ridge, and perhaps closing off the gable vents. Would a
series of passive vents near the ridge work well in conjunction with soft
vents? While I'm told a continuous ridge vent in conjunction with soft
vents is the state of the art, since there are already two passive square
vents near the ridge, I'm wondering if simply adding more passive square
vents would be a sufficient yet cost effective improvement, as long as I
also add soft vents. If I do this, then is closing off the gable vents a
must? What do you think?

Thanks.

Jeff

"jeff" wrote in message
et...
A powered gable vent does nothing but suck air in from the ridge if both
types
of vents coexist.

Well, the roofer is talking about adding a powered vent near the ridge,
not
at a gable end. However, since there are already two passive roof vents
near the ridge, my fear is that the fan would likely cause the two passive
roof vents to suck air in and short circuit the benefit of the fan.

I'm thinking about having soft vents installed plus additional passive
roof
vents near the ridge, and perhaps closing off the gable vents. Would a
series of passive vents near the ridge work well in conjunction with soft
vents? While I'm told a continuous ridge vent in conjunction with soft
vents is the state of the art, since there are already two passive square
vents near the ridge, I'm wondering if simply adding more passive square
vents would be a sufficient yet cost effective improvement, as long as I
also add soft vents. If I do this, then is closing off the gable vents a
must? What do you think?

Thanks.

Jeff



Just add more vents and don't close any of the existing ones. You need MORE
ventilation and any more you can add will help.

Make sure you have enough soffit vents.

Adding a power vent with other roof vents and/or a ridge vent would still be
helpful. That is a bunch of BS that it would be ineffective because it
would "short-circuit" the air. You need more ventilation. Any ventilation
would be good. Any.

jeff wrote:
SNIP Would a
series of passive vents near the ridge work well in conjunction with soft
vents? While I'm told a continuous ridge vent in conjunction with soft
vents is the state of the art, since there are already two passive square
vents near the ridge, I'm wondering if simply adding more passive square
vents would be a sufficient yet cost effective improvement, as long as I
also add soft vents. If I do this, then is closing off the gable vents a
must? What do you think?

Thanks.

Jeff

I'm in agreement with you. Do sufficient soffit vents along with
passive roof vents, but block off the gables, they will not create air
flow

Speedy Jim wrote:

jeff wrote:
SNIP Would a
series of passive vents near the ridge work well in conjunction with soft
vents? While I'm told a continuous ridge vent in conjunction with soft
vents is the state of the art, since there are already two passive square
vents near the ridge, I'm wondering if simply adding more passive square
vents would be a sufficient yet cost effective improvement, as long as I
also add soft vents. If I do this, then is closing off the gable vents a
must? What do you think?

Thanks.

Jeff

I'm in agreement with you. Do sufficient soffit vents along with
passive roof vents; block off the gables, they will not create
air flow under the sheathing (where you want it).
[Sorry, hit SEND too soon.]

Jim

Jeff;

Your problem is two-fold.

I'm going to assume that others have answered your ventilation question.

You also need to address the problem of the moisture finding its way into your
attic, and that means finding and sealing the air leaks in your ceiling.

The most likely culprits will be electrical boxes and recessed light fixtures,
duct and plumbing penetrations, joints between dissimilar planes and materials
and bathroom exhaust fans exhausting into the attic instead of to the outdoors.





On Sat, 06 Mar 2004 21:22:47 GMT, "jeff" wrote:
(Sorry about the last blank post, which was an accident.) Anyway, my
problem is there is mold growing in my attic, primarily on the ceiling,
underneath the roof sheathing, and mostly on the side of the attic in which
the roof is facing the north. I'm looking into getting the mold cleaned up,
but it seems to me I need to have the ventilation issue taken care of first.
A roofer looked at my roof, and doesn't think there are any active leaks.
My roof is less than 9 years old.

My attic is a crawl space that is around 1000 square feet in size, and I'm
guessing that it's maybe about 4 feet high at the center. There are two
gable vents; one on the east side and one on the west side. There are two
passive square vents near the ridge of the roof. There is almost no
ventilation at the soffits, that is, my attic does not have soffit vents,
and, although there are a couple of little places where I can see daylight
near the eaves, this doesn't amount to much.

A roofer is talking about installing another roof vent with a temperature
controlled fan near the center of the roof near the ridge. I'm just
wondering if doing so would be helpful, or would it turn out to be no help,
or problematic? My fear is that the fan might just draw air inward from
the two closest vents, which are the existing square passive roof vents. Am
I incorrect in suspecting this could happen?

My understanding, is that the consensus on the internet is that the state of
the art in attic ventilation is to have continuous soffit vents with a
continuous ridge vents. Since my attic currently already has two gable
vents, plus two square passive roof vents. I'm just wondering if switching
to the ridge/soffit system would be the only real solution to my attic mold
problem, or if there would be a way to improve upon my existing ventilation
system (such as a installing fan). Any ideas. Basically I need to ensure
that whatever I have done ventilation-wise is going to be a real improvement
which results in mitigating the chances of mold growth. Any
recommendations?

Thanks.

Jeff

Exactly. Filling the air leaks between your attic and house
"envelope" should be your first order of business, this is also a
major source of energy loss in winter-time, and in summer time the
stack effect runs in reverse to push hot air down into the house.

Fix those air leaks, and there is a school of thought that venting the
attic is not only useless, it is positively harmful (allowing snow to
come in from outside).

You will hear people tell you the house needs to "breathe," referring
to the living space. But that just means you need a house ventilation
system, and then just for spring and fall (the furnace will pull fresh
air in through leaks in the winter). You can get a ventilation system
on the cheap with a bathroom fan on a 24-hour timer.

Eunoia Eigensinn wrote in message ...
Jeff;

Your problem is two-fold.

I'm going to assume that others have answered your ventilation question.

You also need to address the problem of the moisture finding its way into your
attic, and that means finding and sealing the air leaks in your ceiling.

First, I'd check any bathroom fan vents and see where they go. It's
not unusual to find bathroom fan ducts that terminate in the attic
instead of going outside. Having mold grow in an attic like this is
somewhat unusual without a good source of moisture.

The most critical thing is to get soffit vents put in. The attic
already has at least some outlet vents, but no inlet vents. For more
outflow, instead of cutting any more holes in the roof for localized
vents, I'd go with the ridge vent and just leave what's there in
place. It's just as easy and a lot more effective to put in a ridge
vent.

A power vent is only effective when it comes on at higher temps, while
your moisture problem can be present at lower temps too. And if you
look at the minimum amount of inlet area required to support a power
fan, it's considerable, even for a relatively small one. Without
enough inlet area, you will wind up creating a low enough air pressure
so that cool air is sucked from the home interior via gaps at outlets,
etc. into the attic, wasting energy. So, I'd go with soffit vents and
a ridge vent, forget the power fan.

It goes without saying that a bathroom fan that just vents straight
into the attic is a house destroyer. Run solid duct to the outside
(and insulate to avoid condensation).

The bathroom vent on a timer is not to alleviate moisture problems,
it's to ventilate your house (the envelope, not the attic). This is
an alternative to just letting the air leak out through the attic
which (a) let's warm moist air into the attic (b) let's your energy
leak out. You really only need to ventilate in spring and fall (too
cool to open windows, but your furnace isn't dragging fresh air in).

Fix the air leaks from envelope to attic, and you may not even need to
ventilate the attic. Then ventilate the house envelope itself in a
planned and controlled fashion. Soffit and ridge vents have nothing
whatsoever to do with ventilating the envelope.

A dinky little bathroom fan is not going to create low pressure in the
house, I was not talking about an attic fan which is overkill for this
purpose. Your furnace already pulls air into the house through
windows etc.

Having said that, it is important to do this as part of a whole-house
air-sealing business, so you know where your fresh air is coming from.
Ex: most houses drag in air through the crawlspace, not a very
healthy zone. You should be air-sealing anyway as part of energy
conservation.

See "Insulate and Weatherize" by Bruce Hartey for more information.