Architectural Questions and Answers
1- What is the insulation "R" value of a dome?
Urethane insulation has an R-value of 7.14 at 1" thick, therefore 3" will
give an R-value of 21.42. A concrete wall thickness of 4" has an R-value of
4.44. Therefore, a dome with 3" of foam and 4" of concrete has an overall
R-value of 25.86.
2- What do I have to do to maintain the airform®?
Like all exterior coverings, airforms® will degrade over time. It is extremely
important to set up a scheduled inspection and maintenance program for the airform®.
The coatings page gives good guidance on how to inspect
and set-up this program. If you need further assistance please feel free to contact
3- How do I frame or tie in walls and ceilings to the dome shell?
When planning out the interior layout it is important to detail out how walls or
second story floors will attach to the dome shell. Many architects detail out a
2"x12" bent around the radius as a nailer strip for second story floor
joists, but you will be hard pressed to get it to bend around the radius. In the
past we have sprayed in a concrete ledge which the floor joists can rest upon. It
is important to let us know in the early planning stages if these kinds of loads
are going to be placed on the dome shell so that we can engineer the dome accordingly.
For walls there are a number of ways to frame your straight walls to a radius. The
simplest is to use metal studs which can be snipped and bent to follow the dome
curvature. Conventional lumber can also be used without great difficulty.
4- How do I waterproof my windows and doors?
The key to a good waterproofing is finding one that bonds to the airform®. We
have found very few waterproofing agents which will bond to the airform®. We
have, however, found some primers which will bond to both the airform® and the
waterproofing agent. For flashings over connector roofs a strip of airform®
material can be heat welded to the dome airform® and flashed down over the connector.
Please contact us for your specific waterproofing needs.
5- What is the final shotcrete texture like?
The best way to describe the texture of a shotcrete surface is that of a rough stucco.
When our technicians finish out an architectural building they go to great lengths
to make it as smooth as possible. They will scrape out lines that show after each
6- How can I run my electrical wiring and attach electrical fixtures to the dome
shell so that the conduit is hidden?
During initial planning of the project it is important to discuss the coordination
efforts between the dome contractor and the electricians. After the premat steel
is tied the electricians can come in and install their conduit. It can be tied directly
to the pre-mat steel. J-boxes and outlet boxes can also be installed at this time.
It is important to know a few key points.
A- Design the shotcrete thickness to compensate for electrical conduit runs. (Don't
place 1" conduit in a 3" thick area).
B- Extend all boxes out far enough so that they will protrude out of the finished
C- Mask all boxes to protect them from the shotcrete.
D- Mark all boxes with a protruding or equivalent so that they can be relocated
E- Keep all conduit tight to the rebar.
F- Don't cluster conduit in one area and minimize areas that one conduit runs over