The proper method is under the sheathing, flashed, shimmed etc. but that is an entirely new thread.

There are certainly differing opinions on this.

Some say under, some say on top. If you install flush to the stud face, it makes it a bit difficult to apply a self healing flashing tape/system.

The fact that you would be using a nailing flange window puts you far ahead of the curve to begin with.

Most newer style construction would require that the flange be installed on top of the sheathing, flashed at the sill, jambs and head, and the WRB (Weather Resistant Barrier) installed over the top of everything.

I replaced 1 window several yrs ago. I want to do a few more. Thickness of wall and window thickness go hand in hand. Is jamb depth going to work in my setup? Maybe fin is not positioned right for my situation. That's with a stock window and remodeling. Answer might vary with variables.

If we install a fin window into existing. We prefer to cut the boarding back and then install a drip cap tucked under the siding and existing wrap at the top. Line the window fin with silicone before setting it in will give a good seal.

+1 to that install methodology Andrew.

That is the way to do it.

"Line the window fin with silicone before setting it in will give a good seal."

A nailing flange is not designed or intended as flashing for water intrusion.

Adding some "silicone" does not change this.

Actual flashing (and the self stick variety is actually pretty good now) should be done.

Cutting away the sheathing on an existing house to fasten a window to framing is a really bad idea.

+1

The Tyvek flashing systems are quite good now and a well thought out system.

I think Gulf Breeze, given that he is in FL, was referring to cutting back stucco or cement board. That is how we do stucco or hard board applications here.

Flange should be applied to the sheathing in this case and flashed overtop as Brickeyee is stating.

If you go over wood sheating (say T1-11), are you still going to put a drip cap under the sheating? and if you do that, how are you going to apply the window fin at the top of the window?

Sticky tape does not mean good seal forever.

Not bashing at all, I am really interested, especially if it allows me to change up certian installs.

Seems like people are confusing "sheathing" and "siding" - I consider T1-11 to be the latter.

Could be. When t1-11 is used down here, it is both.

I agree Andrew.

I always prefer to rely on metal. The "sticky stuff" is great on the jambs and sill but you always should have some sort of drip cap or water diversion tool at the head.

If the siding is T1-11, it is both the sheathing and the finish exterior. At that point, cutting it back and putting it against the framing is proper in my opinion.

I'm late to the party here, but I'd say that each of those methods mentioned has an appropriate place depending on circumstances. Ideally you want window tape and metal above it, however there are times where it just is not feasible.
I would trust a caulked flange with closed cell foam and a metal drip cap if it is the best option available.
I generally mount the flange over the sheathing, but I also agree that with t1-11 as sheathing and siding, cutting it back and mounting it to the framing is a better option than putting it on top of the siding and slapping some trim over it. It just adds another layer of protection.

"If the siding is T1-11, it is both the sheathing and the finish exterior. At that point, cutting it back and putting it against the framing is proper in my opinion. "

And leaving a massive repair job.
But combining sheathing and siding is about the height of cheap construction.

+1

Once you tell someone they are supposed to do the siding with the window...they get a glazed over look on their face.

Most T1-11 jobs are tear offs in most cases and going back with Hardie Panel.

We have done a few where we do a cut back on the head jamb enough to at least get a drip cap under there. That gets rid of about 90% of the infiltration issues right there.

Here, most of the time. If the homowner wants siding and windows, then we leave the T1-11 on and that becomes the sheathing. Wrap the house, install the windows on top with tape etc and then hardi or vinyl over that.

Its amazing that FL can be so strict on one thing but then so out of it on other parts.

like impact windows in a mobile home?

Never actually seen one, but I'm sure they exist.