Adding a new window in an existing aluminum-sided wall

I want to add a new window in the wall of an attached garage. The existing garage wall has aluminum siding on the exterior and is just an open studded wall on the interior.
Here's how I am planning on doing it and I am wondering if this is correct. I haven't been able to find any how-to-do-it instructions or videos on the Internet.
My plan is to buy a new-construction vinyl window and cut off the nailing fin that is normally used to nail new vinyl windows to the studs. Then frame out the window opening and cut the existing aluminum siding flush with the framed window opening. Then insert the window in the opening from the exterior and secure the window to the studs with nails or screws going through the sides of the window into the sides of the studs. The installation would be similar to installing a prehung door into a similar opening (which I just did in the same wall). The exterior window trim overlap without the nailing fin would cover the aluminum siding, and then I would caulk the aluminum siding where it is under the window trim using clear 100% silicone caulk.
Is this how it is done?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm no expert, but I seem to recall watching a recent home improvement show where they installed replacement windows from the inside. I think it was on "Ask This Old House".
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks. That was for a "replacement" window where an old window was being replaced with a new one.
In my case, I am adding a new window where no window existed before. So I am buying a "new construction" window, not a "replacement" window like the one you saw on TV. But the problem is that what I am doing is also not completely "new construction" -- it will be a new window that goes in a previously constructed wall with the aluminum siding already in place.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
alta47 wrote:

Make sure you install a header and sill with proper cripple studs.
--
Steve Bell
New Life Home Improvement
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks. I'll definitely be doing that.
Since I haven't heard otherwise from anyone, I assume that the way I am planning to do this is correct. It just seems strange to me that there is nothing out there that explains how to do this. I would have thought that even the window manufacturer's themselves would have instructions for this on their website or somewhere.
All I can find is how to put in a replacement window, or how to install a window in completely new construction before any siding is in place. Now that the Internet is here, I am spoiled and I expect to be able to sit here at my desk and find any information I want. :-)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's not a good assumption. I'm not an expert, but I'm a bit uncertain about the method you propose. How are you going to attach flashing between the sides of the window and the sheathing underneath the aluminum siding? If the aluminum siding can be easily remove and reused like vinyl siding can, I think that would be a better approach.
Cheers, Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I haven't figured out any way to do flashing other than to try to put it in when the opening is cut and try to tuck it in under the existing aluminum siding.
I've been looking at all of the YouTube.com videos on window flashing and none of them describe this situation.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
alta47 wrote:

The main difference between a new window and a replacement window is that the replacement window doesn't have the flashing. You can install it with screws through the frame into the studs, shimming as needed. Expanding foam in the gaps seals it up. Compare this to installing a pre-hung door. Some window manufacturers might give you a more elegant installation method.
--
Steve Bell
New Life Home Improvement
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Interesting. That's how I recently created and installed a prehung door in the same wall. I guess with a replacement window, it is possible that the original window already had flashing.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
alta47 wrote:

What you're proposing is essentially the same as a replacement window. After you frame it in with a header and sill, then cut the hole through the sheathing and outer finish, you're exactly where you would be if you'd removed an old window. It'll just be neater 'cause you won't have to futz with old caulk and casing.
--
Steve Bell
New Life Home Improvement
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.