# Installing attic fans



## Magnettica (Dec 19, 2006)

I'm terrified most of the time when I'm up on the roof, especially getting down onto the ladder, but that's beside the point. What's the best way to cut out for the fan? I use a reciprocating saw but would a jigsaw be better?


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## griz (Nov 26, 2009)

Skilsaw, sawzall to clean up the corners.
I'm with you on the ladder issue.:thumbsup:


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## AustinDB (Sep 11, 2006)

do you have a cordless jigsaw? I would pick up the sawzal b/c I could make the initial cut through the sheathing with it (held at a steep angle of course)...couldn't do that w/ a jigsaw. probably a good idea to make the pilot hole from inside the house so you don't start the hole on the outside too close to a rafter.


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## mrmike (Dec 9, 2008)

I'm with Griz on this one-use a skil saw. Lift the guard & plunge the blade into your mark to start the cut. My 18v Makita usually handles the job-nice without cords up there. Be Careful......................


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## Magnettica (Dec 19, 2006)

I always make a pilot hole from the inside first. 

Thanks for the info.


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## sandboxdoc (Jul 15, 2009)

draw out the square or recetangle on the inside.. drill the pilot hole for all the corners.. then go outside up a ladder and start cutting. Then for sure your right on target for the cut. Judging from magnettica..he most likely has a cordless sawzall rather than jigsaw. I'd say either works but less vibration and more control with a jigsaw.


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## gnxtc2 (Aug 16, 2010)

I tell the owner to have a roofer install the fan and I'll come back and wire it. Personally I don't want the responsibility if the roof leaks. PLus if there is a warranty on the roof, it's not voided.

Billy T.
[email protected]


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## John Valdes (Apr 14, 2010)

gnxtc2 said:


> I tell the owner to have a roofer install the fan and I'll come back and wire it. Personally I don't want the responsibility if the roof leaks. PLus if there is a warranty on the roof, it's not voided.
> 
> Billy T.
> [email protected]


I agree. I would never cut into a roof unless I had to. :thumbsup:


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## Magnettica (Dec 19, 2006)

sandboxdoc said:


> draw out the square or recetangle on the inside.. drill the pilot hole for all the corners.. then go outside up a ladder and start cutting. Then for sure your right on target for the cut. Judging from magnettica..he most likely has a cordless sawzall rather than jigsaw. I'd say either works but less vibration and more control with a jigsaw.


I like that idea alot. :thumbsup:

We use electric sawzalls now. For years the cordless always gave me problems with the blade getting stuck in it's holder and of course the battery always going dead at inopportune times like when on the the roof.


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## rselectric1 (Sep 20, 2009)

Hey Mag,

A little unrelated, but what do you typically set the thermostat at once the install is complete?

I really never know so I set it between 100 and 110.


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## Tom M (Jan 3, 2007)

I go 95 to 100. I agree you should let your roofer install it then you connect it.


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## Tinstaafl (Jan 6, 2008)

rselectric1 said:


> A little unrelated, but what do you typically set the thermostat at once the install is complete?





> *What temperature should the thermostat of the Attic Fan/Ventilator be set on?*
> 
> This usually is set around 110 degrees, depending on your climate. If it seems to run too much, raise the setting by 10 degrees.


http://www.broan.com/display/router.asp?docid=109#Q5

It's a very exact science.


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## dkillianjr (Aug 28, 2006)

For the fans I always install, I usually cut a round hole. What I do is, go into the attic scope it out. Find the rafter pocket I want to use. I'll pound a 16d nail up through the roof dead center of where I want the fan. Usually the fans I buy have a template printed on the cardboard box or I will make one real quick out of the box, its a pencil saver espescially on dark shingles:laughing:. Go up on the roof and just push the template right over the nail. Couple minutes with a cordless sawzall and your good to go. I usually don't drill a pilot hole. Just put the blade backwards in the saw and plunge cut. The nail sticking up also makes a nice handle so your cut out dosen't end up on the first floor!:laughing:


Dave


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## Tom M (Jan 3, 2007)

I do that too Dave good stuff, the shingles cuts usually only need a minor trim, that alone is worth it.


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## jmiller (May 14, 2010)

Magnettica said:


> I'm terrified most of the time when I'm up on the roof, especially getting down onto the ladder, but that's beside the point.


I'm terrified of the thought of getting in the attic. :jester: 

Cordless circular+plunge cut here as well. It ain't finish carpentry.


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## newenergy (Mar 5, 2008)

Some times it's a little tricky to use a hammer and find out where the rafter is, but it's usually easy to find out where it isn't.


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## Irishslave (Jun 20, 2010)

You can cut the shingles first using a hook blade once you are sure of placement, a red lumber crayon will mark good on any shingle, then you can easily cut through sheet goods with jigsaw if it is a circle cut


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## Magnettica (Dec 19, 2006)

A 14" hole saw might be good here too :shutup:


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## crazyboy (Nov 8, 2008)

I've only ever done them with a sawzall, never really encountered a problem yet, but this thread has brought up some good ideas. Being on the roof doesn't really bother me but I would of course rather be on solid ground. I typically set them around 95 degrees too.


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## Magnettica (Dec 19, 2006)

rselectric1 said:


> Hey Mag,
> 
> A little unrelated, but what do you typically set the thermostat at once the install is complete?
> 
> I really never know so I set it between 100 and 110.


Usually I ask the customer and suggest setting it at 100º. 

Motor's going to burn out in 8-10 years no matter what the t-stat is set at or is there something I don't know about t-stat setting for an attic fan?


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## Proby (Aug 22, 2010)

I use either a cordless sawzall or cordless jigsaw, depending on the size of the hole. I take a "tote" with a shoulder strap up with me, I always put an extra battery in it, but I have never needed it. If your batteries aren't lasting for an attic fan cutout, it's probably time for a new set. Check Amazon, they are normally pretty good for new batteries.


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## Magnettica (Dec 19, 2006)

Proby said:


> I use either a cordless sawzall or cordless jigsaw, depending on the size of the hole. I take a "tote" with a shoulder strap up with me, I always put an extra battery in it, but I have never needed it. If your batteries aren't lasting for an attic fan cutout, it's probably time for a new set. Check Amazon, they are normally pretty good for new batteries.


I'm done using cordless sawzalls and/ or jigsaws because battery life isn't what it used to be. Hey come to think of it I need 2 new batteries for my DeWalt crap that still works. :jester:


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## Proby (Aug 22, 2010)

Magnettica said:


> I'm done using cordless sawzalls and/ or jigsaws because battery life isn't what it used to be. Hey come to think of it I need 2 new batteries for my DeWalt crap that still works. :jester:


That's a shame that you're not finding any luck with cordless tools. They seem to be getting better and better, I love the newest Makita offerings.

But my super old Dewalt 18V sawzall and 2-3 year old battery can still get me thru any roof sheathing they put in my way :thumbsup:


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## mrmike (Dec 9, 2008)

Proby said:


> That's a shame that you're not finding any luck with cordless tools. They seem to be getting better and better, I love the newest Makita offerings.
> 
> But my super old Dewalt 18V sawzall and 2-3 year old battery can still get me thru any roof sheathing they put in my way :thumbsup:


I do have a Makita 18v sawsall which is great but I am just in disbelief of how many that use them so much- I only use it as a last resort as they ten to vibrate on the boards, sheathing etc- My first choice is my 18v Makita circular saw which will cut that opening twice as fast as that "vibrator" and it will be a clean cut.........................


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## Magnettica (Dec 19, 2006)

You might say I'm just tired of everything running on batteries. I had all those kits with the sawzalls, circ saw, jigsaw, etc. I still really like the flexible flashlight, that works real good, and of course the radio. Now I have all that stuff at 120 volts so **** gets done faster. So I bought 2 new batteries tonight with a discount card from HD so the radio will be crankin tomorrow. 

mrmike, how are you cutting a circle with a circular saw? Seems that would be dangerous up high on a steep roof.


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## jmiller (May 14, 2010)

Magnettica said:


> mrmike, how are you cutting a circle with a circular saw? Seems that would be dangerous up high on a steep roof.


You just cut an octagon, or even a square. If it's 1x decking you cut a square anyway, out of two boards, but only 3/4 of the way through each board, so they aren't flapping around without support.


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## mrmike (Dec 9, 2008)

Magnettica said:


> You might say I'm just tired of everything running on batteries. I had all those kits with the sawzalls, circ saw, jigsaw, etc. I still really like the flexible flashlight, that works real good, and of course the radio. Now I have all that stuff at 120 volts so **** gets done faster. So I bought 2 new batteries tonight with a discount card from HD so the radio will be crankin tomorrow.
> 
> mrmike, how are you cutting a circle with a circular saw? Seems that would be dangerous up high on a steep roof.










I would also use this puppy before a sawsall for the circle cut in sheathing. And these "battery" operated tools are the "cat's n^ts" in situations like this. I use them constantly & just bring out the corded for real heavy duty jobs. And Mag for safety's sake if your really scared ,tie a rope on the opposite side of the roof to a tree or vehicle etc. & if you can get it over the top & tie it around your waist or onto a safety belt.................


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## woodchuck2 (Feb 27, 2008)

If you tie off to a car you better have the keys in your pocket!!!


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## Magnettica (Dec 19, 2006)

^^

lol!


I'm not buying into this cut out a square for a round fan. That's not very professional. IMO.


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## Tinstaafl (Jan 6, 2008)

Magnettica said:


> I'm not buying into this cut out a square for a round fan. That's not very professional. IMO.


While I understand why you think that, you're not necessarily correct.

A professional does the job quickly, neatly and efficiently. Square hole = four quick straight cuts, vs a much slower and more ragged job with a jigsaw or sawzall.

In this case, it really makes no difference at the end of the day what shape the hole is, but the square one will have been finished more quickly.

As an old carpenter said to me once when I was fussing excessively for perfect fits on framing, half the battle is knowing when it matters. :thumbsup:


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## jmiller (May 14, 2010)

Magnettica said:


> ^^
> 
> lol!
> 
> ...


Next time you're in an attic with box vents take a look at the cutouts. 100 to 1 says they're not round holes, and it's not because the passive vents lacked a cardboard template for the cutout... 

Perhaps what you're failing to picture is that the square can be the same width/height as the diameter of the hole, allowing the vent to be fully effective. 

With a power vent on 1x6 it can be a challenge to get the cutout as big as the fan intake, so if you really want to be professional just derate the fan or install something that sucks more.


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