How to Install Cupolas

Choose the size of your cupola carefully.

Anyone can successfully install a pre-assembled cupola atop a home. Numerous styles, sizes, and colors of cupola are available, to suit just about any taste or décor need. Once used to ventilate the attic of a home, most of today's cupolas are added mainly for decorative purposes. Be sure that you select the correct size for your home. A general guideline is to allow 1.5 square inches of cupola for every foot of unbroken roofline (measured along the ridge). In other words, if you measure 25 feet of unbroken roofline on your home, barn, etc., then simply multiply 25 times 1.5 (25 x 1.5 = 37.5). Using this example, you will need a cupola measuring a minimum of 37 and ½ inches, square. In this case, you might opt for an even 38 to 40 inches. For more than 60 inches of unbroken roofline, a 1 to 1 ratio is used and more than one cupola can be installed. Choosing a cupola that is too small will give the appearance that a child’s toy is sitting on top of your roof. One that is too large will dwarf your home, causing it to appear smaller than it actually is. For larger homes, taller cupolas are available that enhance and complement their dimensions. In either case, basic installation is about the same

Difficulty:

Easy

Instructions

Things You'll Need

• Hammer
• Saw
• Screws
• Screwdriver
• Drill
• Ladder
• Tape Measure
• Carpenter's square
• Pencil
• #10 or #12 wood screws
• Caulk
• Paint and oil-based primer of your choice

Install Cupolas

1. Check angles twice. Cut them once.

   After selecting your cupola, use your carpenter’s square to measure the angle of the ridge of your roof. Note the angle shown on the square. Lay the carpenter’s square on the base of the cupol,a using the same angle. Draw an inverted “V” on two parallel sides of the cupola’s base. Then draw a vertical centerline from the midpoint of the “V” to the base of the cupola on each marked side. Make sure that the angles on both sides are exactly the same.

2. Use your saw to carefully cut along your pencil lines, from the base to the centerline.

3. If you are installing the cupola for decoration only, you should now cut and remove only the portion of your ridge cap that would otherwise rest beneath your cupola. This will enable it to fit tightly against the roof between the two cut portions of the ridge cap.

4. Longer rooflines can support more than one cupola.

   To complete the installation of your cupola, set the cupola in place on top of your roof in the prepared area. It should sit level and rest snugly against the roof. Drill holes that are at least 3" from the corners in both of the uncut sides of the cupola base. Use wood screws of sufficient length to penetrate the roof. Caulk where the base and the roof meet at the angle sides. Fill in the screw holes.

Tips & Warnings

• If you are painting your cupola, it is recommended that you use two coats of oil-based primer first. This should be done after cutting, but before you place your cupola on the roof. You may paint it after drilling and installation.

• After cutting the base to fit on the roof, seal the cut edges with silicone caulking. If caulking is not available, several coats of oil-based primer will do. Unless the cut edges are sealed, water will enter the base, causing the material to rot.

• If you are using the cupola for ventilation, you will need to cut an opening about 6" smaller than the width of your cupola in the roof along the ridgeline/peak. Next, cut down from the peak (on either side of the ridgeline), maintaining a 3"-minimum border inside the cupola base. Cut only the shingles and the sheathing of the roof. Do not cut the ridge if you are ventilating, and never cut the supporting rafters of the roof!

Resources

• Has a basic how-to resource for cupola installation. Also a supplier of cupolas.
• Has a great supply of pre-assembled cupolas to choose from.