Instructions for Building a Cupola

Make a template of your roof pitch. Use a 24-inch square of cardboard. Mark the cardboard in the center along two parallel edges. Draw a line across the center of the cardboard from top to bottom parallel to these marks. Position the template against the roof peak, with the two side marks aligned with angles of the roof and the center line aligned with the peak. Trace the outline of the gable onto the cardboard.

Cut two 24-inch squares from ¾-inch, horizontally grooved plywood siding. Draw a line, perpendicular to the grooves, down the center of each square. Position the cardboard template on the siding, with the peak aligned with the mark at the top of the square, and the ends of the two angles aligned with the sides. Draw the gable outline onto the siding. Shift the template so that the two angle ends are aligned with the bottom corners of the square and mark a the outline again. Repeat on the remaining square.

Cut the outlines of the gable template with a jigsaw to create a V- or chevron-shaped gable end. Cut both pieces the same. Measure the outside edge from the bottom corner to the corner of the gable. Mark the wood shutter to cut two even pieces, one from each end.

Position the shutter pieces along the edge of the gable -- one on the right and one on the left, with the louvers pointing down. Mark the angles of the gable cut onto the shutter. Set your table saw angle to match the line, and trim each end off so that the top and bottom of each shutter piece match the roof angle.

Glue and nail the shutter pieces between the two gable ends to form the box of your cupola. Align the angles cut in your shutter pieces to the angles on the gables. Measure the angle of the gable top and the box along the top of the shutter side, including the thickness of the siding.

Spray the entire cupola box with a coat of spray paint in a color matching your building. Apply the paint with even strokes, holding the can 8 to 10 inches from the surface. Keep the can moving. Work to apply the paint as evenly as possible to prevent runs and drips. Allow one hour of drying time and apply a second coat.

Cut two pieces of ¾-inch thick plywood, 2 inches longer than the gable top and 1 ½ inches wider than the the cupola box. This is your roof deck. On your table saw, cut one edge of each piece of roof deck at the same angle at which you cut the shutters. Place the roof deck on top of the cupola with the angled edges together, forming the peak. The deck should be centered front to back so that the overhang is equal.

Nail the deck in place with one finish nail every 8 to 10 inches. Cut shingles to fit and nail them to your roof deck starting at the bottom edge. Work up each side to the top and finish with a folded shingle over the peak. Use 1-inch galvanized roof nails to secure the shingles.

Position the cupola on the roof, centered front to back and nail through the bottom edges of the cupola with 16d nails into the roof. Caulk along the edges to seal the cupola to the roof.