Any roofers? Wondering about roof vents.

Am putting the roof on the new garage - 25 year 3 tab asphalt. 14 square.
Wondering about venting.
The soffit will be perforated aluminum.
I like the looks of the continuous ridge vent rather than the square, raised box type vents.
If I go with the raised box type vents how many do I need for a 1000 sq ft garage.
Another factor is I recently removed an attic fan and patched the ceiling for a lady. I kept the 2'x2' fan and was going to install it in the garage ceiling.
I think they just vent out the roof vents.
Would that make a difference which type of roof vent would be better?
Looking for thoughts/opinions from the brain trust.
Thanks

Ridge vents with open mesh fiber filter work well and self compute the amount needed. There are more leaks with the box vents and it is necessary to use local codes to set the number/size needed. Jim

Definitely go with the ridge vent. Your lucky if you get .75 sqft. of venting per can. You get about .35 sqft. of venting per foot of ridge vent.

one thing that is overlooked with ridge vent is snow if your vents are covered up by snow they cannot breath we use gable end vents mine are 18x12 and let a lot of air through summer and winter

Hey Dog. What do you do in your shop ? If you weld a lot, spray paint or have a solid fuel heating system you are venting all the fumes and suspended particles into the ceiling and ultimately the roof vent. If not it isn't an issue. Many roofs I worked on and especially steel we used the mesh cap across the entire roof. When I was first introduced to mesh I thought that driving rain and snow would penetrate them, but it doesn't. It is an excellent way to vent and leaves no area of the roof or attic without good air flow. We left an inch to inch and a half on each side of the peak, thus approximately 3" which the roof mesh cap covered very nicely. I'm not against roof vents , you can put them all on one side of the peak so they don't show from the street or whatever view you wish. A power vent is the ultimate , this is thermostat controlled , pulls an incredible mass of air very quickly. I have one on my house and I wouldn't be without it. Good luck with whatever you decide on.

There is a formula, so many sq in /sq ft ridge and eve vent. Personally I don't think you can have too many vents. Ridge vs roof about the same.

If old shingles were curved you need more vents. Eve vents are as important as roof or gable vents.

Dimensional shingles last longer and look nice. I reshingled the farm house last year. The wind off the fields is harsh and those old style three tabs were coming off. The new shingles are heavier and hold up to it. Just a thought.

I used to start my vent about a foot off of each end, so basically the entire ridge. If you're worried about looks, they make a vent material that's made of perforated black plastic, and you shingle right over top of it. I don't think it works quite as well as the standard ridge vent, but it's not as noticeable
Regarding three tab vs. architectural shingles; you'll be much happier with architectural's - around here three tabs are special order anymore
Pete

A couple of added thoughts.
Roof Depot told me the architectural shingles are actually cheaper now days.
But I still went with the 3 tab as I was able to get the same brand and color as the house.
I do have the plastic, continuous vent at the peak of the house - the type you cover with shingles. I it has a fiber mesh stuff in it.
I was concerned about them plugging up if you ever do much welding, etc which I will.
I doubt I'll ever paint in there. The overspray makes a mess of the place in a hurry.
Another thought I've had is build an airtight chute from the ceiling/attic fan and vent it to the outside on the back gable end. That wouldn't reduce attic temps but would pull air through/out of the garage yet prevent the ridge vent from ever plugging.
It's cold and windy up there today but I'll have one side done by quitting time.

Everything we have has continuous ridge vent, that seems to be the way to go. One thing I have worried about is the house has a hip roof, so the ridge is not full lenght of the house, we probably should of put a square roof vent on the S end.

You should go with architecture shingles. Longer warranty, dont mold, or black streaks. I used the hard plastic roof venting for ridge-one foot from each end. Just did my 24x24 Gambrel roof.

I've installed hundreds of roofs with 3 tab asphalt shingles with no problems. Just repaired a roof where someone nailed the architectural shingles in the wrong place....fixed 88 leaks!
Anyway, nothing wrong with the aluminum vents that are boxed in and angled at the top....if you use enough of them. Stay away from the ones that have a square cap covering the round hole. Snow and blowing rain can be a problem with those.

If you use ridge vent do not use gable vents. Ideally you want an even air flow from the soffit vents to the ridge or roof vents. Most roofers will install plywood on the inside of gable vents to close them up if they're using ridge vent.

Something to think about with the fan is it will blow welding soot and such out your vents and could discolor your shingles (or vented soffit if the fan moves enough air).

After seeing 3 of the thermostat controlled roof mounted fans catch on fire I disconnected mine.

One other consideration....if you plan on selling the place go with architectural shingles.

I would go with the ridge vent. Shingles are whatever, depending on what your budget is. If wind is a factor ,I?d go to a 6 nail shingle pattern.

1 2. 2. 1. I tried it, on a roof that had blown shingles before, not one since.

Just curious- how do you nail architectural shingles in the wrong place?

One caution on architectural shingles- you have to install them on a "clean" roof (not over a previous layer of shingles). I did, and roof was shot in 10 years. According to the guy who installs most of the roofs around here, there's something about them that makes them "cup" and drain sideways if not laid down flat on a clean roof (don't remember exactly what he said). He said he still gets calls from people who want to leave the present layer (like you used to be able to do with 3 tab) to save money, and he politely declines.

As far as the vents, go with the ridge vent- faster to install, looks better, and seems to work fine.

(quoted from post at 18:48:35 10/11/18) Just curious- how do you nail architectural shingles in the wrong place?

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Nail spacing...If the two center nails aren't spaced correctly, they can be too close to the joint in the course above or below. Some were directly in the joint!

(quoted from post at 13:43:48 10/11/18)

If you use ridge vent do not use gable vents.

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This is very important. If you leave the gable vents open the air flow in the attic will have a tendency to travel from the gables to the ridge. You need the intake air to come from the soffit area only. Same problem with the turbine whirlybird vents. They can actually get their makeup air from the ridge vent. Path of least resistance.
You should not have 2 venting systems at the top of the roof.

There is plenty of good advise here so just 2 quick thoughts. There and not a durned thing wrong with 3-tab. A lot of good products out there and 3-tab is one of them. Just keep an eye on them for sealing down in our balmy fall weather. I have seen ridge vent plug in wooded setting where the snow dumped on the roof and didn?t blow clean. But that doesn?t sound like your case here. Conversely, I?ve also seen box vents create a negative draw in a small auxiliary attic area and actually suck snow in.

Not answering the post but for information ... up here, most roofing on homes/garages is still asphalt shingles but no longer the paper-based asphalt shingles. They are all fiberglass-based asphalt shingles. They look much the same, and probably 90% of homes now use the architectural style, people like the looks of them and they are more forgiving for the installer I think. There were some warranty settlements against IKO and BP shingles up here due to problems with the older paper-based ones. When we replaced our shingles about 4 years back, I filed a claim and got some money back from BP, it didn't amount to a whole lot though, maybe less than 10% of the new roof they put on for me.

GAF
The U.S. Federal Housing authority recommends a minimum of at least 1 square foot of attic ventilation (evenly split between intake and exhaust) for every 300 square feet of attic floor space.
https://www.gaf.com/en-us/for-professionals/tools/ventilation-calculator

Owens Corning calculator
https://www.owenscorning.com/roofing/components/vent-calculator

I still say if your shingle are curling up at edges, add more ventilation.

I?ve also seen power vents suck moisture into the attic and
create an ice cave. Explain that to your insurance when the
Sheetrock falls off in spring.

You can not over ventilate the attic or crawl space (use what ever type of vent you like just use enough). You can under ventilate both.

Yes they do mold.

When we built our hose we used the vented eves along the bottom edge of roof. Then used proper vent in between rafters to keep insulation from stopping flow of air.Then on both gable ends I used electric gable fans with thermostats.

(quoted from post at 15:06:35 10/11/18)

(quoted from post at 13:43:48 10/11/18)

If you use ridge vent do not use gable vents.

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This is very important. If you leave the gable vents open the air flow in the attic will have a tendency to travel from the gables to the ridge. You need the intake air to come from the soffit area only. Same problem with the turbine whirlybird vents. They can actually get their makeup air from the ridge vent. Path of least resistance.
You should not have 2 venting systems at the top of the roof.

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3 X on this very important venting to begin on lowest possible point in roof system to highest possible best being the ridge. Adding venting in between will short circuit causing dead spots in the air flow. The usable space of your building should be a sealed box with the roof system just a cap. The goal is to get the attic as close to outside conditions as possible, and still shed the elements. I have vented many roofs and replaced many due to unvented or sealed systems. I've seen where short circuiting air flow can cause additional condensation from heat loss or overheating.
I used countinous ridge venting wherever possible, usually go from roof end to end just because it looks better. The are several good brands for shingle over ridge vents and I prefer the mesh types and never had issue with plugging,and vent the soffits countinously wherever possible.
I don't encourage venting usable space to the roof but exhaust directly outside.
Many years of 3 tab shingle install that have had very good life if installed correctly and good ventilation was in place. Shingles installed in cold conditions and not having good heat and sun directly after tend not to seal as well.
I also used the rafter vents that D beatty pictured all the time and never regretted it.
I roofed a neighbors house 32 years ago with 25 year IKO 3 tab shingles following these practices replacing rotted roof boards, resheathing. They look like they could easily do another 10 years, best part is that they are still happy with job and still a great neighbor.
These are practices I've used with very good results for many years. Good Luck and happy building!

Correct...The vent should create a chimney effect ..heat rises...pull air in the bottom of the attic (lowest
point)...let it vent out the top (highest point). Be sure the little plastic channels ( through the insulation) are
not crushed or blocked. Gable vents in combination with ridge vents nullify the effect.