people think you just screw a box into a 2x4

but there is a heck of a lot more to it than that.

For starters,

the box for your ceiling fan

will need to be centered on the window,

so you need to find the center,

and mark it,

using a level, to make sure your center line stays straight.

Then, 

you need to measure how far your mark is from the closest board

Two lines away from 6 inches.

(do NOT tell my dad I measured like that)

(it's so much faster than calculating how many 16th or 32nds

 or however the many marks there are on this thing)

Then you have to move your ladder closer to the center nailer

(that's what you call a board that is there

 for the sole purpose of (drywall or soffit) being nailed into)

and hope that that 2x4 running across the porch is straight,

and mark the center of the window there, too.

Because that nailer runs directly down the center of the porch,

and we didn't want to move it

(although, I'm hoping now that this wasn't a bad decision)

we decided to just put our can lights as close to the nailer as possible,

so that the center of the lights and ceiling fans would be 39 1/2 inches

from the OSB on the house.

You see there is nothing above the nailer to attach a light/fan box to.

Poop.

So you'll need to find either a 2x4 or a 2x6

to put there.

If your screws are longer than the depth of your 2 boards put together,

you'll want to angle them slightly;

you don't want any sharp ends up there to poke through wire insulation.

That picture was totally staged.

You can't screw into a board

without applying weight or counter pressure!

Your top board will lift up as soon as the screw hits it,

and you'll have to back the screw out,

and try again.

With two hands.

Then you'll need to screw it into the other nailer 18 inches away.

And add a screw from top to bottom, 

for good measure.

Now that you've got a board securely in place,

you can transfer your center mark.

Using a square ensures it's nice and straight.

Next you'll need to measure out to where you want the center of your fan.

And use a square there, too.

Now,

if you were applying drywall,

or a standard depth ceiling material,

you'd be good to go,

and could now screw in your box.

But we are putting cedar on our porch ceiling,

which is thicker.

Before the kids left for Summer Play Days at church,

Brandon and I did some maths,

and figured out that we needed a sort of shim that was not quite 3/4 of an inch.

So he used the planer 

and made a board that was 22/32nds.

 I cut my shim from that board.

Now that we've got our shim, let's get back at it.

You'll want to be sure you have all of your tools,

because it is really annoying to keep having to get down from your ladder

to grab something you forgot.

If, like us,

you need a shim,

you'll want to screw it in, with just one screw,

Dammit Bobby!

It's hard to hold up a board

and a screw

with one hand.

and remark your lines.

X

marks the spot!

Then unscrew your shim

and climb down off your ladder

and line up the holes in your box

with the lines on your shim.

And your box will be perfectly centered.

:-)

Partially screw in your screws

(shorter ones, 'cause these can't go in angled)

Then take it back to the ceiling

And first screw in your shim,

making sure the screw goes into the same hole,

so that your box ends up in exactly the right spot.

Then completely screw in the pre-screwed screws,

and add a few more screws to your shim.

We don't want a shimmying fan...

And that,

is how you install a box

for a ceiling fixture.