Gable Vent

[Mike Hanan]

Does anyone have a design for an 18" octane gable vent?
I am looking for the angle and size of the louvers.
I am installing an attic gable fan 16.5" and want the best airflow.

Thank you
Mike

[George Yetka]

This may be one item I would buy. I thing they are about $50 in PVC

[Tom M King]

The drawing shown on the first page of this site should be all the plans needed, but the prices look pretty hard to match for DIY unless time is worth nothing.

https://www.kimballdesigns.com/10octagon.html

[Tom M King]

The old house in the picture needed some but never had any. Every roof peak was a different angle and each side was a little different. I just figured each one out on the workbench as I was building it. I used 3/4" Cypress and 1" spacers for the openings stuck together temporarily with 23 ga. pins that were pulled out before final assembly, marked the required angles on the pieces that were cut to run long.

It would have taken more time for setup figuring out 6 different angles. I just marked them and cut them with 10-1/4" circular saw with all the parts pinned together.

I probably have some better pictures somewhere, but this was 16 years ago so they're hard to find. You can see one of them in the gable with the unfinished chimney. They have hardware cloth and screen on the inside. Yes, I do masonry too. The chimney stacks on this house stood off the house a foot, so there is air circulation to those vents.

[Maurice Mcmurry]

I used 3 inch wide quarter sawn basswood 5/16 thick for slatts and spaced them 1 1/2 inches apart. I wish they were aluminum. I sure dread painting them. These are over 30 years old. Darling wanted me to improve our curb appeal so a parked the CASE on the front porch to pretty things up.

IMG_1999.jpg IMG_1959.jpg

[Tom M King]

I remembered where a picture was of one of the gable vents on that 1828 house. I had to rent a lift to fix a roof leak about a year ago. I didn't have anything to do with that roof other than keep getting calls to fix leaks. It's just a poor design of metal shingles. I think Duration was the SW top of the line paint when these were painted 16 years ago. Peak is 39 feet above ground level. Each side of that roof slope is a bit of a different angle. They were probably nervous up that high when they were framing it.

I said I cut them with a handsaw earlier, but remembering better now, I cut them with a plywood guide and a 10-1/4 circular saw with all the pieces pinned together. Ends and backs of all the louver pieces were primed and painted before assembly. There are two vertical battens fastened to the louvers on the back to help them hold the spacing with the long spans.

[Andrew Hughes]

I had a gable fan running on my house for a short year nothing but problems. The first side I had it installed cooked the grass and plants because if the 100 degree plus air.
So I moved it to the other side of the house. The fan would come on at night and vibrate the wall it could be heard from the bedrooms.
Big thumbs down for attic fans
I installed turbine fans that turn from natural air flow.
Good Luck

[Maurice Mcmurry]

I get to replace power attic ventilators on a regular basis. The life span has gotten shorter and shorter over the years. I think the last "Made In The USA one I installed was about 30 years ago. it lasted 20 years, since then I have put 3 imported ones in the same house. Having plenty of free air space for them to blow out of helps them last longer. I recommend the style that blows out of the roof rather than the gable end type. For gable ends spring loaded aluminum louvers are my recommendation. Most of my clients do not want that look on their home.

https://www.zoro.com/dayton-16-in-ba...E&gclsrc=aw.ds

[Cameron Wood]

I posted on this yesterday, but it is not here.

Best airflow and louver vents are mutually exclusive.

Not too hard to make as half the louvers are cut square, and the rest share the same compound angle.

A kind of cheating way to make one would be to make it square with angled dados in the sides, temporarily fasten the louvers in position, and cut the corners off on the bandsaw to make the octagon.

I agree with above that attic fans are a short-lived PIA. Almost all that I have come across did not run. I am a fan (pun?) of roof turbines.

[Bruce Wrenn]

Remember that old Sears RAS you couldn't wait to get rid of.. Louver shops had a pair set up for right and left cuts. As for fans lasting, did they get oiled annually? New ones have a "one time" built in overload. When bearings get dry, it pops. Game over!

[Maurice Mcmurry]

Remember that old Sears RAS you couldn't wait to get rid of.. Louver shops had a pair set up for right and left cuts

I used the Sears radial arm saw to make mine. The saw has held up better than the louvers. The saw got to live indoors. A flaw I often find with attic ventilation is mesh or perforations that are too small. Cottonwood fuzz trying to get in and bits of cellulose trying to get out can quickly plug regular insect screen and perforated vinyl or aluminum louvers. I use hardware cloth no smaller than 1/4 inch behind the louvers.

[Tom M King]

The house I grew up in was built when my Dad came back from WWII. It didn't have air conditioning. There was a 4' attic fan at the top of the unfinished upstairs with no protection of any kind. I was always scared to death of it, for good reason I expect. My Dad would go upstairs and open a window at night and turn the fan on. Windows had wooden screens on the outside that were changed to storm windows in cold weather. I remember the air felt wonderful coming in the window by the bed then.

The rental house has a 3' attic fan in one gable that is obviously older than the one I grew up with. It's hung on each corner by a coil spring. There are grease cups at the bearings to the fan shaft. It was one of many things that wasn't working when we bought that house. It's hard to get to, but when I went up to see about it the only thing wrong was the bolts holding down the 1/2hp Marathon motor had shed their nuts. It was a simple fix with some locktite and some 90W. It went right back to work after I replaced the "switch" which was two 20 amp 120V breakers with their handles taped together with a proper 240V breaker. The building that was turned into that house was supposedly built in 1963, but I'm pretty sure that fan is much older.

[Mike Hanan]

I posted on this yesterday, but it is not here.

Best airflow and louver vents are mutually exclusive.

Not too hard to make as half the louvers are cut square, and the rest share the same compound angle.

A kind of cheating way to make one would be to make it square with angled dados in the sides, temporarily fasten the louvers in position, and cut the corners off on the bandsaw to make the octagon.

That is exactly what I did, made a 16 inch square vent with the louvers then cut off the corners.
Just installed it today and the vent looks like it has always been there .

I'll the fan later this week in the AM.
Way to hot to get up there now.

Mike