It is geodesic, with the foam cut into triangles. The dome is three frequency truncated at 5/9 of a sphere. The reason it is 11'D is that a triangle just fits the width of the foam sheet, actually getting 3.5 triangles from each sheet for a total of 105 triangles from 30 2'x4'x4" EPS sheets. These triangles will be glued together with an adhesive made for foam, the seams will be taped, and then a nylon mesh will be embedded in an acrylic cement mix on the outside to stop UV deterioration. Since foam should be behind a fireproof layer I'll spray papercrete on the inside as a fire barrier. It looks like it will work out to less than $5 per square foot and will be insulated R16+.
Of course, if I wanted to use a higher frequency dome, I could make a much larger one with similar sized triangles. I designed for the least waste with the available size of foam, losing only 1.4" from the end of each 4' sheet of EPS.
I know Judith is out schlepping rock for a rubble trench foundation and cooking some tasty food for next week's gathering, what is everyone else doing in the nice cool late summer weather? Summer is over in three days, the equinox is the 22nd, but the weather guessers are saying we are going to get hot again for a while after all the rain from that massive low pressure system at four corners. Supposed to be a warm fall this year, and I don't mind since I still have a lot to do before the first frost.
spaceman
J.S.M wrote:
How are you going to hold the arch of the dome.
From: Spaceman <Spaceman@starship-enterprises.net>
To: papercreters@yahoogroups.com
Sent: Friday, September 18, 2009 2:44:29 PM
Subject: [papercreters] Test message/foam dome
As there have been no posts for two days, the question was asked if the list is still working. If you are reading this, it is.
I'm not doing pc today, I'm making a hot wire cutter for some styrofoam that will become a 11' dome. It's experimental, and I'm planning on spraying pc on the inner surface for fireproofing. The outside will get a thin layer of acrylic based concrete finish to keep the uv away. When I get to the "on topic" stage of spraying pc I'll post some pictures.
spaceman
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