WHAT DOES ATTIC AIR SEALING MEAN?

Fill any holes with wood filler and you should definitely have sound wood where you'll screw the new window in to the frame for balance. If you find destroyed or rotten Wooden, remove it and Reduce new wood to exchange it. Attach new pieces with screws and wood glue. Acrylic is non-porous, there’s no hazard of water destruction when installed ef