# installing full frame windows with existing siding



## mlmaher (Nov 18, 2007)

I need some advice on how to install new construction full frame windows and keep my existing aluminum siding intact. How do I properly weather proof the nail fin and flashings? Removing and replacing the siding is not an option right now. And I do not want to use pocket windows. I like the Integrity Ultrex series. Currently my home has single pane double hung windows with the exterior storms and aluminum siding. Is there a solution where I could cut back the siding to properly install the flashing and then use some sort of trim to cover the flashing?


----------



## Ron6519 (Mar 28, 2007)

If you want to maintain the exterior siding, new construction windows are not the correct choice. You would go with replacement windows that would use the frame of the windows you have.
Why are you using new construction units?
Ron


----------



## AtlanticWBConst. (May 12, 2006)

Generally, you need to remove the siding around a window opening, in order to properly install and flash a new-construction type window.
However, it is possible to install a N/C window, if you have enough room to flash the nailing fins. The general rule is that you want approximately 4" of space around the window and to the siding edge, to apply flexible flashing over the fins. You can cheat this measurement. 
Figure out what you have for a window Rough Opening, and also har far your installed alumnium siding edge is from that R.O.
As stated, you can cheat that down. What you want is obviously enough space for the nailing fins to lay flat, and still be able to apply a flashing over the fins, that will stick to the sheathing. 

FWIW: We prefer to use Tyvek tape over the nailing fins, because it lessons the thickness of the area around the window (nailing-fin thickness + Flaxible flashing thickness = can equal as much as 1/4").

You can then install your trim boards around the area after that. My advice is to use a PVC composite type trimboard, and install it so the edge meets up to the Aluminum J-Channel.

Here is a picture of the the area I am referring to. The siding here is wood, but the "concept" is the same:


----------



## mlmaher (Nov 18, 2007)

*answer*

Thanks Atlantic! That is exactly the type of solution that I was looking for. Question, do I install a J-Channel around the siding that I trimmed back to edge it against the PVC trim board? Sorry if I have the terminology wrong.


----------

