the company that is doing the shell for my add-a-level are putting in replacement windows....there is no "nailing fin"
Is this okay? should I insist on something more? I was told that they should be able to add a nailing fin, is this so? is this neccessary?
Is this necessary...yes it is.
Some window manufacturers make the 'fins' or nailing flanges that can be retrofitted onto their replacement windows.
Personally, we don't like the kits we have run across (Most don't create the weatherproof seal you get with New Const. windows), and we prefer only actual new construction windows for new construction installations.
That doesn't mean that the ones that are going to be used on your home are not good...it depends on the manufacturer. (FWIW - looks like someone messed up the window order somewhere along the line)...