nailing fin versus caulk

[beckyfield]

What is the proper way to install replacement windows? After talking to several vendors, I am confused. If a replacement window comes from the manufacturer with a nailing fin attached, shouldn't it be used? Why do other window vendors/installers remove the nailing fin and just use caulk? Thanks for any advice.

[Guy]

Becky, it all depends on the application. Some manufacturers make a nominal sized frame which can be used in either application. Their frame is made at 3" or 3.25" with fin applied. Usually you can order them with the fin removed. Sometimes we remove them in the field. We would only do this when doing an insert application. A new construction application would require the fins to remain in place and be back caulked before installed. By caulking the back of the fin you get a good seal to the wall board. This creates a barrier to prevent leakage into the dwelling. If your installer is cutting off the fin and caulking them in place on the outside. You should be throwing down your Shenanigan Card right away. They should have a blind stop that butts the frames exterior side. They should also have some kind of stop on the inside. This is what holds the window from falling out. Now we don't deal with to many aluminum windows here in MN. If we do it's out they go completely. I'm not sure what they do when the frame stays in place. In either case, caulking should not hold your window in place with a couple screws!