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i have seen some mold on the ceiling of my upstairs master bath,it has a shower. anyway,abobe that ceiling is an attic with insulation,an attic fan and gable vents. however,we have no ridge vent on the roof. do you think adding the ridge vent will rid us of the mold problem from all the moisture in our bathroom?
 

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is the fan venting directly into the attic?it shouldn't be

you should leave the vent on for awhile after useing the shower/bath,they have fans with timers on them
 

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Discussion Starter · #3 ·
Tom
we have an attic fan but NO vent in our bathroom..i am thinking the moisture cannot escape. perhaps a ridge vent will do the trick by the moisture traveling through the ceiling and out the ridge vent?
 

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oh i would definitely consider putting a bathroom fan vented to the outside

is there a window? even if there is i would install a fan and use it

i don't know if a ridge vent would help much with bathroom moisture issues,the ridge vent is outside the building envelope
 

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I Second the bathroom fan vented via ducting to the outside wall or roof...do not vent this into the attic unless you want more mold.

And I do believe ridge venting, gable vents and an attic fan would be for the most part contradictory ... not to mention ridge venting is about as expensive as venting gets.
 

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copper magnet
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i have seen some mold on the ceiling of my upstairs master bath,it has a shower. anyway,abobe that ceiling is an attic with insulation,an attic fan and gable vents. however,we have no ridge vent on the roof. do you think adding the ridge vent will rid us of the mold problem from all the moisture in our bathroom?
Sounds like you might have two separate problems:

Too much moisture in the bathroom and maybe inadequate attic venting.

I second (or 3rd or 4th) the bath fan vented to the outside and suggest looking at your attic venting situation. Is there inlet for the vents on the roof? It sounds like you may have adequate exhaust, but you need to let replacement air in somewhere.
 

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More expensive than running wire and paying for electricity to run a power roof vent? Hmm.
Note: I said about :laughing:.

As far as passive ventilation goes, it is far from the cheapest. And there certainly is a reasonable selection of crappy ridge vents on the market, buyer beware!

In most cases a standard roof vent system will do. I see ridge vents going on all over the place, when there was no real issue in the first place. The biggest issue with with ridge venting I see, are guys failing to support the roof deck after making their cuts. Indeed, ridge vent installation is a laborious task at best, although as a system, it is the best.

Anyhow, this thread really should have nothing to do with ridge vents :laughing:.
 

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yep, ya need a fart fan. where ya run the exhaust point depends on a few different things.

in the past i've always said to run it strait to the roof (via insulated flex hose), and through a damper vent. i'm now starting to re-think this approach, as i'm seeing it result in more ice damming due to the snow melt around and below the vent.
 

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I dunno what kind of effect ridge vents would have on this situation.

Since your attic is insulated, heat would have a tough time passing through the insulation. You would have air circulation up there, but i don't think it would be enough. To get ride of mold on your bathroom ceiling.

Do you have a vapour barrier on your ceiling?

With all the steam and heat coming off the shower, you need some place for it to vent. The fan is the perfect solution, where you vent it through is up to you.

It would be better to install the fan and use it after a shower, than having to re-do your bathroom cause of mold and rot issues found later on down the road.

-Bill
 

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OK, here's what I think.

The bathroom needs a fart fan, sized to move the appropriate number of CFMs based on the size of the room. I prefer to vent them through the side of the building with a gable end if possible, to prevent the moisture from being pulled into the attic via soffit venting.

As for attic venting, if you have gable vents, adding a ridge vent is pretty much a waste of time and effort, because a ridge vent is designed to create airflow through the soffit vent, along the bottom of the roof deck and out the ridge vent. A gable vent will offer a path of less resistance for the ridge vent to draw air from, defeating the benefit of soffit venting.
 

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Note: I said about :laughing:.

As far as passive ventilation goes, it is far from the cheapest. And there certainly is a reasonable selection of crappy ridge vents on the market, buyer beware!

In most cases a standard roof vent system will do. I see ridge vents going on all over the place, when there was no real issue in the first place. The biggest issue with with ridge venting I see, are guys failing to support the roof deck after making their cuts. Indeed, ridge vent installation is a laborious task at best, although as a system, it is the best.

Anyhow, this thread really should have nothing to do with ridge vents :laughing:.
I agree, there are a bunch of ridge vents available, but only a few that actually perform properly.

yep, ya need a fart fan. where ya run the exhaust point depends on a few different things.

in the past i've always said to run it strait to the roof (via insulated flex hose), and through a damper vent. i'm now starting to re-think this approach, as i'm seeing it result in more ice damming due to the snow melt around and below the vent.
No, you have it correct. Through the roof is the best place. If you vent it through the soffit or wall it will get drawn in to the attic again.

See below :thumbup:

OK, here's what I think.

The bathroom needs a fart fan, sized to move the appropriate number of CFMs based on the size of the room. I prefer to vent them through the side of the building with a gable end if possible, to prevent the moisture from being pulled into the attic via soffit venting.

As for attic venting, if you have gable vents, adding a ridge vent is pretty much a waste of time and effort, because a ridge vent is designed to create airflow through the soffit vent, along the bottom of the roof deck and out the ridge vent. A gable vent will offer a path of less resistance for the ridge vent to draw air from, defeating the benefit of soffit venting.

I always wondered about gable vents affecting soffit draw. It makes sense to close them up if your mold is in the lower portion of the roof to force the intake through the soffit
 

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i know that we're drifting off topic here, but oh well.

when laying out the plan for roof ventilation, ya have to provide for intake (generally soffit vents or drip edge vents) and exhaust.

if ya choose ridge vents for the exhaust, you are supposed to block off any pre-existing exhaust vents (usually gable vents). the reasoning is that the air will "short circuit" and the ridge vent will be pulling in through the gables, instead of the soffits.

another biggy i see has to do with multiple ridge lines. here the rule is if there is more than a 3' difference high, then ya only vent the upper. less than 3', vent both.
 

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you are assuming that the gable vents are drawing in air,why?

by their placement high on a gable wall they are probably exhausting air along with the ridge vent

there used to be a roofer here that did a smoke test on a model

and i believe it showed the gable vents also exaust

not saying its not a good idea to block them,just saying you really can't assume
 

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copper magnet
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you are assuming that the gable vents are drawing in air,why?
and i believe it showed the gable vents also exaust
not saying its not a good idea to block them,just saying you really can't assume
Right. Every situation is unique. I've seen the inverse where air was entering through the gable vent and going right back out the ridge vent.

I've seen many instances where there is minimal or no soffit venting, but gable vents in both ends. One acted as inlet and the other outlet. In a situation like that, the gable/ridge combination probably works better than then the gable vents alone.
 

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page 79 of the certainteed shingle applicator's manual 9th edition:

never mix two types of exhaust vents,

"when ridge and soffit ventilation is added to an attic with other vents in place, such as gable end vents, box or turbin static vents, or power fans, you must remove or block off the other ventilators. when installed properly, ridge and soffit systems draw air in the bottoms (soffits) and out the top (ridge). other open ventilator holesin the roof or gable will shortcut the low to high draft and diminish the ventilation effectiveness."
 

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Install an exhaust fan that vents to the outside in the bathroom. Everytime you use the bathroom run it. Consider having a timer on it so it continues to ventilate the space after the person using it has left. Semi gloss latex enamel paint or oil based semi gloss should be acting as a vapor barrier so the conditions in the bathroom shouldn't be having an impact in the attic and vice versa

On the attic ventilation, if you have gables on both ends they should be providing good cross ventilation. The rule of thumb (and of a lot of building codes) is 1 square foot of ventilation per 150 square feet of attic. Having a whole house fan that is pulling air up into the attic complicates things as you're adding a lot of air to the space. If the attic is nice and dry I wouldn't worry about it
 
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