Eyebrow vent placement

Roofing/Construction Questions
1

My roofer said the low profile eyebrow vents I am considering go on both sides of he peak and opposite each other. We get breezes up here every day, so I am wondering would not the air come in the windward vent and go straight across and out the opposite vent? Sure this would to pull up only a little air from the eaves right? So I was wondering if having them all on the side of the roof away from the wind direction (99% time the wind is from the west) the air passing over the peak would create a negative pressure over those eyebrows and pull the hot air out…plus it would look a lot better not having eyebrow vent on the street side.

What do ppl here say?

2

wow, that’s pretty sophisticated thought on ventilation for a homeowner. You must be smart, or at least think you are. I can hardly comprehend it. I always put the vents on the back so you don’t see them, well, that’s usually where they were before I started :slight_smile:

I’ve heard so many opinions on venting that my head is still spinning like a wind turbine. i just know you need some venting and want to suck from the eaves and out the top.

peace

3

That ALMOST sounded like a compliment LOL!

Seriously this is my first house and I am going to keep it for 15 years, so yes I tend to over think things. It also amazes me how little professional roofers understand their product. For instance I asked several bidders if I installed a ridge vent should I close off the gable vents so air will come up thru the eave vents instead of bypassing the eaves and coming through the higher gable vents. They all said “no, the more vents the better” except one crusty old-timer…he pre-empted me, as soon as I said I was considering a ridge vent he said “if you do that you MUST close off those old gable vents”. He is the leading contender for my work so far although not the cheapest.

I was reading up on ridge vents and one manufacturer stated they work best on a windy site as the wind passing over the peak creates a negative pressure on the other side…makes complete sense.

So does my concern about opposing eyebrow or dormer vents allowing wind to enter at that level and continue out the other side…not much air from the eaves will be sucked out I should think?

And yes I agree there is a lot of variance between what different people recommend, but what i want IS for air to enter the eaves and exit the top, as efficiently as possible and without depending on active fans.

Having them on the side away from the wind direction (and the front of the house) might work well, or there might be turbulence/eddy currents as wind passes over the peak, so maybe the air will NOT be pulled out by a relatyive negative pressure gradient…could be disrupted air entering :slight_smile:

Just wondering if there was a standard or building code, or if anyone has temp readings to show it worked just fine on one side only, or had done canister smoke experiments …

The only reason i am considering eyebrow vents is one contractor told me the ridge vents work fine when new but over time get dirt and dust which reduces performance. This is the plastic rollup style ridge vent.

[quote=“we love tearoffs”]wow, that’s pretty sophisticated thought on ventilation for a homeowner. You must be smart, or at least think you are. I can hardly comprehend it. I always put the vents on the back so you don’t see them, well, that’s usually where they were before I started :slight_smile:

I’ve heard so many opinions on venting that my head is still spinning like a wind turbine. i just know you need some venting and want to suck from the eaves and out the top.

peace[/quote]

4

put them all on the back side.

#1 for looks.

#2 for the “Bernoulli’s principle” or similar “Venturi effect” which, exactly like you stated, creates a low pressure zone, effectively sucking the air out as fast as it can come in the intakes on windy days.

5

Thanks! Nice to meet a roofer that does not have the “it makes no difference” attitude :slight_smile:

[quote=“Agape”]put them all on the back side.

#1 for looks.

#2 for the “Bernoulli’s principle” or similar “Venturi effect” which, exactly like you stated, creates a low pressure zone, effectively sucking the air out as fast as it can come in the intakes on windy days.[/quote]

6

It WAS a compliment dude. I’m just saying you’ve probably thought it through better than 90% of roofers I know and you should trust yourself if you know something. Keep doing your own research and then pay the cheapest guy who nails in the nail strip to do it YOUR way. That way YOUR the one benefiting from your knowledge.

Just think about this with as much effort as you use to think about the physics in your attic…there are a ton of good roofers(if you can find them) who don’t know anything about venting, but they can take off your shingles and put down a nice new roof with whatever venting you want for a good low price. That way you actually are the one who benefits from knowing something… and then I can put you on my list of cool people who “get it”

hope it goes well with you

7

[quote=“we love tearoffs”]It WAS a compliment dude. I’m just saying you’ve probably thought it through better than 90% of roofers I know and you should trust yourself if you know something. Keep doing your own research and then pay the cheapest guy who nails in the nail strip to do it YOUR way. That way YOUR the one benefiting from your knowledge.

Just think about this with as much effort as you use to think about the physics in your attic…there are a ton of good roofers(if you can find them) who don’t know anything about venting, but they can take off your shingles and put down a nice new roof with whatever venting you want for a good low price. That way you actually are the one who benefits from knowing something… and then I can put you on my list of cool people who “get it”

hope it goes well with you[/quote]

I agree

That poor roofer is going to hate you though…

8

I personally install them on both sides but never right across from each other so there is no chance of blow through. My reasoning is that for 1: its not always windy so its good to have them on both sides. 2: wind does not always come from one direction. 3: if you install high quality eyebrows, they dont look bad and should not be hid from site as they are a functional part of your roof. 4: since im into high performance vehicles, Gm designed a hood called a cowl induction which draws air in at the cowl in a reverse scoop. Even though it may draw air out being on the back side, it may also pull some air in. i havent seen a real test to see what exactly happens but those are my theories. And yes you should block off gable vents.

as for the eyebrows i use, i use O’Hagin vents, they are low profile, pre painted(coated) and are wind/rain proof. they are designed to not allow blowing rain to enter, but let air freely flow out. they are being use in most tile roofs now out here in california and on many new high end housing tracks. i would recommend them any day over the other products out there. heres their site:

ohaginvent.com/

good luck!

9

Yep, Ohagins are the best!

10

Good to see a homeowner care about his roof.

Here is a link to some more information.

roofingcontractorreview.com/ … ation.html