Hello There, the upvc mouldings were coming away from a couple of windows and I have removed them to be replaced with similar 28mm wide strips around them. I'm having a senior moment however and having just filled in the holes that were left from pulling the old strips away and rubbed them down evenly....should I undercoat first before applying the strips with mastic or as someone suggested in the local, apply apv before sticking on the strips and then painting?