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When Do You Recommend Installing A Cupola?

Ai recommends that you build the cupola only if you want third floor loft and if you will use it. A cupola added on top of the larger domes, 40', 45', or 48'  creates enough headroom so a third floor loft can be built. A ships ladder is installed so you can climb up into the loft from the second floor. For example in a 40' dome with a cupola, a third floor can be built so you can stand in the loft and see out the windows.

A cupola is not available on the 22' or 27' domes.  To vent hot air out of the top of the 22' and 27' domes, install an exhaust fan in the top of a second floor interior wall.  The ducting for the fan can run thru the vertical second floor wall and second floor joist and vent out under an entryway.    Second floor window dormers are not available in the 22' or 30' domes. To get opening windows on the second floor of the 30' dome, use a cupola and for indirect light use a few skylights. 

The cupola is a way to add height to the top center of the dome and another way to have opening windows. If you install a cupola and do not install the third floor, you will need to use a ladder to clean the windows.

Does a cupola change the

structural integrity of the geodesic dome?

No. In hurricane areas you would want to install shutters over the cupola windows or install impact resistant glass to prevent the glass breaking from the force of the winds or debris being slung into the glass.


The cupola does not weaken the rest of the dome, but the cupola is more vulnerable to wind loads because it sticks up at the top. In high winds the overhang panels could come off. They are nonstructural and would simply be replaced after the storm.


In wind areas you do not want the cupola windows to be more than two feet tall. Also taller cupolas just look out of proportion on the dome.

The following is an overview of the Cupola Construction.

The top five component panels of the dome make up the cupola top with overhang panels (eave panels) added on site.

  • The topside exterior of the five pentagon panels of the cupola is prefinished steel reinforced concrete. These panels have seven inch thick E.P.S. insulation.

  • The overhang/eave panels consist of 3 1/2" thick E.P.S. wrapped in steel mesh. The underside of the eave panels have prefinished concrete.

  • The topside and edges of the eave panels are stuccoed onsite.

The actual cupola assembly instructions consist of six pages. The subcontractor and four laborers take two to three days to build and assemble the cupola. Yes some form of hoisting mechanism is needed to lift the cupola panels to the top of the dome. The cupola is made by installing the top five panels on top of a five-sided concrete wall that contains the windows.

  • The first step is to form and pour a concrete beam around the top opening which reinforces the opening.

  • Next, set 2x4 window frames in place on top of the beam.

  • Then form and pour a concrete column at each of the five corners.

  • Finally, install the five panels and there C1 extensions on the top of the wall and concrete the seams.

  • At anytime thereafter you may install the windows and finish the interior.

Third Floor Loft Heights And

Square Footages

Please see the floor planners in the back of the Stock Floor Plan Booklet for loft heights and square footages. The outline of the third floor loft matches that of the cupola. The 22', 27, 30' and 34' domes cannot have a third floor loft.


Dome Size Loft Maximum Sq.Ft. Height in Loft

Ceiling Height under Loft

40' 112 sq.ft. 5' 6" 7' 6"
45' 142 sq.ft. 6' 10" 8'
48' 170 sq.ft. 8' 1" 8'


If I do not install a cupola on the dome,

how does the hot air and moisture get exhausted from the top of the dome?

In a vertical wall near the top of the dome and in bathrooms install bathroom exhaust fans that can be turned on to exhaust hot air and moisture. Use dryer ducting for the exhaust fan ducting. It extends down the interior wall, through the floor joist and vents out under an entryway.


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