Abstract: J-channel member comprises a relatively rigid plastic back leg and channel bottom wall, with spaced apart slits along the length of the back leg to permit bending of the bottom wall around a radiused opening, and a relatively flexible plastic front leg which permits stretching of the front leg during such bending of the bottom wall while leaving the front leg intact. At the outer end of the front leg is an inturned annular lip which is urged radially inwardly into engagement with the trimmed ends of vinyl or aluminum siding received in the channel to help hold the siding down and enhance the overall appearance of the joint.

Abstract: Ventilator system includes an external panel and interior baffle defining a plurality of vertically spaced air chambers vertically sealed from one another to prevent water droplets in any one of the air chambers from draining into the lower air chambers. Air passages in the baffle communicate with the respective air chambers at a higher elevation than air passages in the panel. The air stream entering the air chambers through the panel swirls and slows down prior to being discharged through the baffle. Also, side cavities communicate the ends of the air chambers with each other and with a catch basin below the air chambers. Within the air chambers are flap valves which close off the baffle air passages when the force of an air stream entering the air chambers through the panel exceeds a predetermined level to prevent water blow-through under high wind conditions.