They have numerous studies that show these to be very effective yet I read on another thread where people are saying they do not work at all? What say you?

Ugly. Out of style. Doesn't fit w/modern architecture.
But 1000% functional!

Ridge/soffit venting has become a moot debate with all experienced & IQ/professors' studies showing no other system better.

ref blog at The Money Pit radio show
https://www.moneypit.com/

All ventilation systems work. However, they have to be done properly and to a degree suitable for each house and roofing system. I have several customers that noticed an immediate impact on indoor comfort by adding ridge vent. That said, I added 75' of it to for example and they were coming from two turbines or 4 air hawk systems which are inadequate for the roof size by a huge margin.

If you look at nearly 85% of new builds (my guesstimate from what I experience), the ventilation is completely lacking. I'm talking about the houses that come to a point and they have 4 static dome vents. If you run some of these into a basic roofing calculator, you'll see they need a hundred feet of ridge vent, 10 dome vents, OR 23 airhawks….or something considerably more extensive than they have.

I have rarely seen anything like that on new builds unless it is a mindful builder.

That said, as mentioned already, you must have adequate intake to match the exhaust. Adding ridge vent to a house with no soffit vents will gain very little.

Ridge vent does typically cool more effectively because you can usually get plenty of it on a house. It's a more even distribution of air flow and it works through basic convective principles all the time. It has no motors to wear out…which is often the main issue. Some builders put in 4 power vents and that may be ok but in 3 years when those motors cease to function, it's a basic static vent that is woefully inadequate.

Even if there isn't adequate soffit vents, you can add intake vents on the decking to accomplish the same thing. With todays tech, there is no reason not to have adequate ventilation aside from cost reasons for a homeowner.

Yes, so how many sq ft of soffit venting is needed per sq ft of home? How many LF of ridge vent.

I always read and understood that ridge/soffit venting is better than whirly birds, air hawks, powered vents, etc.

jt2hunt said:

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Yes, so how many sq ft of soffit venting is needed per sq ft of home? How many LF of ridge vent.

I always read and understood that ridge/soffit venting is better than whirly birds, air hawks, powered vents, etc.

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At minimum

Attic sq ft /300


Take that number / 2


So 2100 sq ft attic/ 300 = 7 sq ft total venting

50% for intake, 50% for exhaust

So 3.5 sq ft or 504 sq inches for intake and the same for exhaust

Or just use a calculator



https://www.gaf.com/en-us/for-professionals/tools/ventilation-calculator

Thank you

Ridge venting is 12-18 sq inches per LF
Hardi soffit vent is 5 sq inches per LF

4000 sq ft of attic

960 sq in each way
or 80 LF of ridge venting
192 LF of soffit venting

Agree completely with Jason's well thought out answer. All the various systems can work, pick the one that fits your roof design the best. Most are lacking around us because they are not installed properly or adequately.

Regardless, don't expect even a perfectly installed system to make your attic equal to the outside temperatures. But do the best you can.

This is a good thread with good questions and links posted on it. I like it.

What's your opinion on hip ridge vents? The next time our roof needs replacing, I'm wanting to get rid of the annoying whirly birds and have all ridge venting.

Y'all got this figured out already but I'll add that Owens Corning uses a slightly different calculation option which will yield twice the ventilation it says you need. I usually try to use the 1:150 rule because it will allow me to estimate for more. You can't really have too much in my opinion. The GAF uses a 1:300 I believe. I have found either to be tremendously better than what many currently have. Whichever you use, make sure you are using the product it specifies as you've chosen. There are many varieties of "slant back vents" and not all manufacturers have the same capacities.

As for hip vents, I don't install them often. Most of my business is insurance based, and honestly, most people just don't want to pay the extra for the additional venting. I can usually do some nice upgrades, but due to many homes needing a redo of ventilation systems, I can't usually absorb the whole cost of that. However, GAF, for instance, sells a product exactly for hip ventilation and as long as you install it per directions, it's a fine product. It accomplishes the task. It is installed a little different in terms of how it's cut in. It still requires adequate intake. But, as I mentioned, they sell eave louver products for that as well. I like hip and ridge vents because they don't stand out, they work well, and they are passive with no moving parts.

Even on these 107 degree days at 3pm, I can FEEL the hot air coming out of ridge vents when I'm doing inspections. The air outside is 107, the roof surface is 130, and with all of that, you can still notice air moving and heat coming out of the ridge when you are close to it. They work.

On top of ventilation making the house operate a bit better, on a conventional home, it also extends the life of the roofing surface.

Yeah I have maybe 14 ft of ridge vent and 2 whirly birds. Plenty of intake, but don't think it's enough exhaust. Tons of length on the roof for hip vents though

Looks like they tried for the 1/150 rule on my home seeing how much intake there is, but the amount of exhaust is far too little

When they built my house the builder at least tried to provide some ventilation with ridge vents and all-around soffit vents, but the monkeys who did the insulation blew insulation into most of the void spaces above the soffit vents. No way for air to flow up into the attic. Been slowly working on correcting that.

Man, that sucks. Those baffles aren't expensive. Sucks they didn't throw those in. Either way, hopefully you can pull it back with a rake or something. It'll still work fine.

If it makes you feel better, I've taken off ridge vent and airhawks when reroofing, and found the roofers never cut slots or holes for them. Lol. I've also found big 14" holes cut for vents that the roofers clearly ran short on and just threw some shingles over it.

As with everything in life, specs mean nothing because it's only as good as the installer.

Brings up bad memories of getting sued by a HO because she wanted more ridgevents than the calculations and soffit could support. Said we cheaped her by not doing all the ridge lines. No amount of experts and calculations would make her happy - though ultimately some cheddar did.

Just wanted to add my sad story about how sometimes homeowners want things that make bad sense and sometimes contractors do things to HOs that make bad sense. Education is key and this forum is almost always spot on.

Jason, I have a home built in 2004 that relies exclusively on ridge vents. It has soffits all around that are open. However, my house has very few ridges (the roof is sort of pyramid shaped and comes almost to a point, although there are sub-roofs over the garage and a few other places that also have ridge vents that are lower than the peak of the roof).

I suspect that I don't have enough ventilation since my attic gets smoking hot. I wonder if those lower ridge vents have the same problem as combining ridge vents and whirly-birds? That is, air is being pulled up through those lower ridge vents rather than through the soffit vents.

Finally, my roof is fairly new. I've only owned it for a year, but I believe that the roof was replaced after a hailstorm 3-4 years ago.

My questions are:

1. Is there anything practical I can do now, or should I wait until the next hailstorm and talk to a roofer about venting at that point?

2. How do I find a roofer that knows what they're talking about when it comes to attic venting? I've talked to a couple already and was unimpressed. They seemed to want to replace shingles and anything beyond that was beyond them.

Thanks! Your comments on this board are extremely helpful!

If your roof is pretty new, there is no reason to wait or reroof. You can likely just add to what you have. If you want, shoot me an email of the address and I'll scope it out on satellite and give you an idea of how much you should add. If you're in my service area I'll get you a price but if you aren't, a reputable roofer should be able to do what you say to do and I can help you with that Info.

To answer your first question, if you have multiple ventilation systems, they can work against each other but they can also work together. For instance, if you have ridge vent and power vents below them, then the power vents are probably sucking air from the ridge and doing very little. If they are static dome vents, then the ridge and dome vents can act as one big vent and air will convect through both.

Thanks very much, Jason. Email sent.

Jason_InfinityRoofer said:

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Man, that sucks. Those baffles aren't expensive. Sucks they didn't throw those in. Either way, hopefully you can pull it back with a rake or something. It'll still work fine.

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They put a baffle in here and there, maybe a handful or two for the whole house. Looked like more of an afterthought than anything thought out. I don't know how many baffles are recommended for a typical attic perimeter, but if the ventilated soffit covers the entire perimeter the very few baffles they added looks awfully inadequate.

From the sections I've worked on they didn't just seal off the chokepoints where the roof slopes down across the top plates, but actually filled up the voids above the ventilated soffits. So I'm having to suck the insulation out with a blower and then adding what gets sucked out to areas of the insulation layer that looks a little skimpy. Very slow process due to difficulty in gaining access all around the perimeter of the attic.

I am not a roofer but I have heard much the same as several have posted in that you get so many different opinions on what is best. I definitely have been told some combos, such as ridge vent with power vents and no soffit vents, are a bad idea. Just putting out a couple of real life systems that seemed to work for me (not my idea, but set up by builders that seem to really know their stuff):

2200 sq. ft old house. Recently remodeled a little, but also had a complete new roof put on. Previously had gable vents only, NOTHING else. Attic was miserable. Builder had complete functional ridge vents put in, and I went crazy and cut into all the soffits and put screened 4 X 12" vents all along, must be 1500-2000 sq. inches total. The attic is MUCH more tolerable.

4000 sq ft commercial building but built custom home style-the builder lined the entire soffit with the hardi type soffit vent which is not obstructed by insulation. He also put in, must be about 20 of those air hawks on the north side of the building only, and he has 2 gable vents on the south and east sides. That is one of the most comfortable attics I have ever been in.

Can you explain more or provide a picture of what an air hawk is? I've never heard of them.

http://rb.gy/y07tt

Thanks!