Make sure the house is level and upright. Use the sliding bevel to find your angle for the tongue and grove panels where they meet the soffit. The tongue and grove panels are 145mm x 15mm. Measure to the bottom minus 20mm, this means the end of the panels are clear of the ground so only the bearers will be in contact with the ground.
Mark and cut the angle and clean up edge with a block plane. Offer up and fix. Glue and screw the panels and glue the panels to the frame as well, this will make it rigid. Check your angle again and use for the other panels.
