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roofing ventilation question for the peanut gallery...

slyfink

Turbo Monkey
Sep 16, 2008
9,288
5,028
Ottawa, Canada
Hi all,

I'm having my roof redone, and in seeking quotes, we had one contractor say we'd be better off getting "ridge ventilation" over the more common "tall ventilator" vents that are on neighbouring units. (like this
1652901166061.png
). That contractor said those types of vents would suck too much air out of our roof, including the air we have heated/cooled. Ultimately, we're not going with that guy, but that doesn't mean he doesn't have a point.

But I really don't know, and I imagine I can ask the roofer we're going with about it. But since I know jack shit about this, I also don't want to cause an unnecessary delay in booking him because our roof is in really (really) bad shape. We really should have done this last year.

FWIW, we have "semi-cathedral" ceilings, in that the ceilings are really high (+/- 16' at the peak), and the attic is probably no more than 2' "thick".

Any thoughts or comments on attic venting are welcome...
 

sunringlerider

Turbo Monkey
Oct 30, 2006
3,573
6,267
Corn Fields of Indiana
I have a ridge vent and two functioning cupolas. We have a huge attic and with the amount of insulation up there I am not concerned with excessive heat loss and more concerned with condensation due to our relative high humidity.

With such a small attic I would think you would get away with a ridge vent
 

Westy

the teste
Nov 22, 2002
54,225
20,003
Sleazattle
Hi all,

I'm having my roof redone, and in seeking quotes, we had one contractor say we'd be better off getting "ridge ventilation" over the more common "tall ventilator" vents that are on neighbouring units. (like this View attachment 176578). That contractor said those types of vents would suck too much air out of our roof, including the air we have heated/cooled. Ultimately, we're not going with that guy, but that doesn't mean he doesn't have a point.

But I really don't know, and I imagine I can ask the roofer we're going with about it. But since I know jack shit about this, I also don't want to cause an unnecessary delay in booking him because our roof is in really (really) bad shape. We really should have done this last year.

FWIW, we have "semi-cathedral" ceilings, in that the ceilings are really high (+/- 16' at the peak), and the attic is probably no more than 2' "thick".

Any thoughts or comments on attic venting are welcome...
Venting requirements where you live may be very different from most people here, hopefully @Jozz can add his $0.02 I beleive he has the technical and climate background you seek.
 

Westy

the teste
Nov 22, 2002
54,225
20,003
Sleazattle
I have a ridge vent and two functioning cupolas. We have a huge attic and with the amount of insulation up there I am not concerned with excessive heat loss and more concerned with condensation due to our relative high humidity.

With such a small attic I would think you would get away with a ridge vent
Vents let the air out, you still need a pathway for fresh air to get in.
 

boostindoubles

Nacho Libre
Mar 16, 2004
7,838
6,145
Yakistan
If your insulation is in the ceiling between your house and roof (like blown in) the attic space should not have conditioned air. Heating/cooling un-used attic space is a terrible waste of energy.
 
show us your portfolio of bong sheds
these of course are spec homes. projects that my clients that actually live in are not shown out of respect for their privacy.




https://www.zillow.com/homedetails/24220-Long-Valley-Rd-Hidden-Hills-CA-91302/19882832_zpid/
 
Last edited:

sunringlerider

Turbo Monkey
Oct 30, 2006
3,573
6,267
Corn Fields of Indiana
these of course are spec homes. projects that my clients that actually live in are not shown out of respect for their privacy.




https://www.zillow.com/homedetails/24220-Long-Valley-Rd-Hidden-Hills-CA-91302/19882832_zpid/
Those are cool, but do they have a bong shed in the back yard?
 

jdcamb

Tool Time!
Feb 17, 2002
19,799
8,383
Nowhere Man!
I thought this would be a pretty straightforward thing. It is not. I got varying answers from 3 sources of reliable info or so I thought.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,776
4,695
Champery, Switzerland
these of course are spec homes. projects that my clients that actually live in are not shown out of respect for their privacy.




https://www.zillow.com/homedetails/24220-Long-Valley-Rd-Hidden-Hills-CA-91302/19882832_zpid/
Dang! Nice work man.
 

slyfink

Turbo Monkey
Sep 16, 2008
9,288
5,028
Ottawa, Canada
Vents let the air out, you still need a pathway for fresh air to get in.
architect by trade here, FWIW, if the air in your roof/attic is being heated/cooled by your ac or heater, you're doing it very very wrong. all airflow thru the attic should be just natural air. 1 square foot of venting for every 150 square feet of roof space...
Yes forgot to mention the louvered vents on the attic walls on either end
yes, forgot to mention I definitely have soffit vents as well, so I'm going to assume there is proper, sufficient air flow between the attic and roof...
Where do you live?
Ottawa, Canada. So very similar climate to @Jozz : cold in winter, hot and humid in summer.
these of course are spec homes. projects that my clients that actually live in are not shown out of respect for their privacy.




https://www.zillow.com/homedetails/24220-Long-Valley-Rd-Hidden-Hills-CA-91302/19882832_zpid/
dang... very very nice... certainly not within my financial reach, but very nice indeed!

thanks all for your feedback... this helps with perspective :thumb:
 

boogenman

Turbo Monkey
Nov 3, 2004
4,290
973
BUFFALO
Here in Boofalo, NY we have the same climate with the exception of more snow and maybe a touch warmer in the winter. Pretty much all homes just have a ridge vent for top of the roof ventilation.
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,030
5,918
borcester rhymes
I've been looking into this a bit as I have what I think is insufficient attic ventilation, causing ice dams in the winter and some condensation/mold issues.

Anyways, my understanding is there is no such thing as too much ventilation, just too little. The only way to have too much is via a powered vent/fan, which can draw conditioned air out of your living space, or to have poor airflow by means of poorly designed ventilation.

We have ridge vents, chimney vents (like what you showed), gable vents, but very few soffit vents, and I think that's the problem. The gable vents ruin the airflow from the soffits and out the ridges. Should be an easy fix, but just haven't gotten there yet.
 

vivisectxi

Monkey
Jan 14, 2021
466
566
yeast van
balancing intake & exhaust is key. mixing up vent types can be problematic as well (ie, if you don't have enough soffit ventilation, the gables and/or roof vents could be acting as intakes to feed the ridge so you're not getting enough draw at the soffit, which may lead to the problems described).

sly - if you've got a (at least partially) vaulted roof, i'd be using a continuous ridge vent. looks better as well (no ugly vents peppering the roof).
 

Poops McDougal

moving to australia
May 30, 2007
1,179
1,241
Central California
Another Architect here, although I don't work on residential, or even wood structures very often; so take this with a grain of salt. One of the potential downsides to continuous ridge venting in a climate like yours is the vents becoming blocked by snow during the winter. Attic ventilation is critical during winter, as well. The taller vents that your neighboring houses have help prevent that problem.
 

Jozz

Joe Dalton
Apr 18, 2002
5,752
7,214
SADL
Ridge vents with two foot of snow might not vent well. Choosing the right amount of venting needed is affected by insulation thickness and air tightness of your envelope. Venting is needed for condensation. If you have a tight envelope and loads of insulation like R60, venting is not critical. But if you have basic insulation and punctured envelope, then more heat loss will generate more condensation. There are many models of maximum vents. Some are pulling less air.