Install window in steel siding

[CADman]

I have steel siding on my house, and would like to add a window.  Without taking the siding off, other then the hole for the window, how do I do this?    

Thanks in advance.

CADman

[chips ahoy]

I have steel siding on my house, and would like to add a window.  Without taking the siding off, other then the hole for the window, how do I do this?    

Thanks in advance.

CADman

I would talk to a window installation company.

Mel

[crokett™]

I have steel siding on my house, and would like to add a window.  Without taking the siding off, other then the hole for the window, how do I do this?    

Thanks in advance.

CADman

I imagine it would be much the same process that I used to install a window in my previous house that was brick.  

1.  remove the interior wall covering and insulation
2.  remove any studs.  
3.  frame the new window opening - jack/king studs, header, etc
4.  cut the wall sheathing out in the new opening.
5.  drill through the siding to mark the corners of the new rough opening
6.  go outside, mark the cut lines on the siding using the holes you drilled, and cut it.


I've used a similar process to install a window through vinyl siding. There I had to cut the siding back from the rough opening enough to allow for brickmold/trim.  I don't have much experience with steel siding, does it sit in some sort of j-channel around the window trim like vinyl does? If so, you should be able to put the j-channel in before the final window trim and/or the window goes in.  I put the j-channel in under the siding, then I put the window in.

For steel siding I'd probably use an angle grinder to cut it.

[Snipe Hunter]

Steel or aluminum ?

[Snipe Hunter]

I recently took out a small window and installed a much larger one on the second story of our house. I didn't want to remove the siding, mostly out of fear that I'd screw it up or damage siding that I can't replace.

The problem with not taking off the siding is that it's difficult to install J-Channel with siding on. You can cut back the siding and install trim boards around the window but you still have to nail the J-Chanel under the siding, or rely on caulk (and constant maintenance) to insure it doesn't leak. I'll also never have to repaint trim boards.

Maintenance forever vs almost maintenance free.

After much consternation.... I removed the aluminum siding and did it right. It wasn't as difficult as I thought it would be. It was the right thing to do for several reasons.

1. I could wrap the opening properly with flashing.
2. I could use a "new construction" window and nail it to the sheathing and studs, New construction windows can be a good deal cheaper and more "off the shelf" sizes are available. I used the stock Pellas from Lowes and ordered 2 "mull kits" for $28 to mull three windows together. Because the Pella windows have a fold down nailing flange, I could install the window in one piece from the inside. Push it through the opening and fold out the flange to tail it in place. No shimming or nails/screws through the frame of the window. A much cleaner installation.
3. I could install the J-Channel snug against the new window so a minimal amount of caulking was used and properly fit the replaced siding in the J-channel.

I honestly think it was just as fast installing it with the siding off than it would be if I left it on and I have a much better installation.

[Jasen]

What kind of metal siding? 
The 2 most important things is 1. the pentration wrap, you need to get something behind the siding and into the RO, slip tar paper or even better, Vycore behind the siding as best you can, the farther the better, 6" would be ideal but probably not feasable.
2. and most important is getting the window properly caulked to the siding, if this fails you still have the tar paper or Vycore there, but that is only your back up system. Smearing caulking out onto the siding is not the way to go. Get some L galvenized metal like a 3/4x3/4 that you can frame the siding with to give you something good to caulk to would be the way to go. You can bed the L metal to the siding with a good sealnet like Dow Corning 795, do a nice job as 795 in not paintable, but I believe 748 is paintable.
Now you can install a backer rod to fill most of the dead space, which will also be your bond breaker, you don't want caulking to adhere to all thee sides of your gap or your seal will  most likely fail. The backer rod should set back from the face of the siding 1/2 the width of the gape between window to siding, you want to create an hour glass shape with the caulking.