opening. Measure from the soffit to the base of the upper lock on the previous course of panels. Subtract 1/4''. Mark this dimension on the panel to be cut, measuring from the bottom edge of the panel. It is a good idea to check the dimension in several locations along the length of the wall. Using a snap lock punch, punch the vinyl siding along the cut edge every 6", so the raised tab is on the outside face. Push the siding into the undersill trim that has been nailed in place along the top of the wall. Furring may be needed to maintain the face of the panel at the desired angle. The raised tabs will catch and hold the siding firmly in place. Transition from Horizontal to Vertical Finish the last course of horizontal siding with the J-channel and/or finish trim. Install a drip cap and a J-channel. The top piece of J-channel must have minimum 1/8" diameter weep holes drilled no more than 24" apart to allow for water runoff. Transition Transition from Brick to Vinyl Siding Caulk where the sheathing meets the brick or stone exterior. Flashing should be caulked where it meets the brick or stone and a drip cap should be in place. If horizontal siding is used, a J-channel or starter strip may be used. If a starter strip is used, it is necessary to provide at least 3/8" clearance for proper engagement of the siding. Use a J-channel to receive vertical siding;