Identify the location of the studs behind the exterior wall of the house. Use a stud finder or knock gently along the wall with a hammer to find the studs. Mark the positions of the studs with white chalk for easier identification. Ensure the studs are about 16 to 24 inches apart.
Staple builder's felt along each chalk line to mark the studs. This will help drain away condensation.
Cut a piece of clapboard 1 1/2 inch wide with the saw, long enough to cover the length of the wall. Nail the clapboard horizontally along the bottom of the wall to install a starter strip.
Draw an arrow at one end of a piece of plywood to mark your starting point. Mark off lines from the arrow to the other end of the plywood. These should be at least 1 1/2 inches narrower than the siding. The result is a swing stick that helps space your clapboards evenly.
Draw a straight line from the end of the wall to the nearest window. Ensure it's in line with the bottom edge of the windowsill. Hold the swing stick vertically between the corner of the house and the window. Ensure the arrow is at the bottom of the wall and in line with the starter strip's edge.
Check whether the line beneath the swing stick corresponds with any chalk line on the wall. If it does, draw the rest of the lines on the wall, using the stick as your guide. If it doesn't, tilt the marked side of the stick toward the chalk lines until one line coincides with the swing stick. Draw the lines onto the wall while using the marks on the stick as your guides.
Place the clapboard on the wall so it overlaps the starter strip. Use the hammer or nail gun to nail the clapboard onto the lines you drew along the studs. Repeat this step on the chalk lines to space the other clapboards.