do we need to have the window chaulked before we put up the j chanels around the windows for our siding?

Answer 1

Yes it will make a better seal then if you caulk the J-channel to the window. Plus if you get a little messy, you don't have to worry because the J will cover it all up. If it's a new home then you can cover over the edges of the window with that edge sealing tape and not caulk at all.

Answer 2

caulking is a must! be sure to use a very good grade of silicone caulk when caulking joints between window and house I agree with Dan..

Answer 3

for water not air other wise, you'd fill the weep holes Too!