Originally Posted by bluefitness
The window is installed under the siding. There is no sheathing because it is T1-11 siding. The layers are:
ice and water
nailing flange (window)
I would suggest:
1. Take a router and flatten out your t1-11, take off about 1/8" (2"-3" all around the opening).
2. Use Pella window flashing tape (Lowes) from where your flattened out the t1-11 over to the window (make sure you have a good bond with the window).
3. If you can trim the outside with Azek instead of Cedar do so.
4. Use a good poly caulking and caulk between the window and your trim and around the edges of the trim.
5. Get a can of BLUE Great stuff and foam the rough opening making sure that the foam is able to expand out to the window flashing tape. <---just don't let it bow the tape!
6. Check the caulking twice a year.
7. Install vinyl siding over your existing siding when you get some extra money.