Cut top F-channel 1/8” smaller than width of opening. Fasten rail through leg with #8 x 3/4 wood screws. (See figure 1)
BASIC PORCH ENCLOSURE INSTALLATION INSTRUCTIONS
Cut side F-channels approximately 1 1/4” shorter than opening height. Check opening for accuracy. Please note, if using 3/4” angle to trim out bottom edge, cut rails 2 1/8” shorter.
You can caulk F-channel before installing. However, this step will make it more difficult to remove panels in the future, should they need repair.
When using S/990 screens only, be sure screen spline faces inward.