So first the research. I spent six years looking at solutions. Everything from slide-off to round observatories. The biggest thing to take into consideration in my case was CC&R's. You know the rules of a neighborhood that dictate your life. So the concept of a slide-off was out, because it would definitely not be approved by the Home Owners Board of Nazis. Everything has to be taken into consideration. Diameter, Height and Obstruction of view for the neighbors. So the first step was to see if the neighbors had a problem with me building my dream. The good news is, I have been setting up a SKYTENT for about 5 years, four weeks a year and they were used to seeing a dome.
The second step was to take pictures, examples and all that I could to the Community Association Board. It took some doing and talking but I eventually was "granted approval" to move forward.
My first goal was to insure no vibration. This meant the earth has to be packed and solid. First win for me, I have 18 feet of calichi dirt. This stuff is like Adobe Brick and as hard as rock. So compacting this was futile, but I did have it tamped for about 1 hour.
Then came the layers above the dirt. It is a simple formula, but one that will insure a solid foundation. After tamping the dirt base for one hour we then placed a 50 mil plastic vapor barrier down. Then the biggest part of the base is Type-2 aggregate. If you know the concrete business, this is the best thing to put underneath your concrete. It was also tamped for one hour to a thickness of 6 inches. After tamping is was watered three times over two weeks to help it setup. Once it setup it had a strength of 140PSI. This alone was like cement.
The most important part of the puzzle was the concrete. I noticed almost all the sites I visited they used bag mix or driveway concrete. Not quite what I had in mind. So on 10-Jan-06 I am using 20,000PSI concrete. This means that any given inch on the surface can withstand a force of 20,000 pounds on it. To further strengthen, I used 1/4 inch wire mesh and 1/2 inch rebar. The concrete is 8 inches thick. So overall there is 8 inches of concrete and 6 inches of Type-2 aggregate. The Pad is 11 feet in diameter allowing me a 6 inch larger surface. There is a 3 foot sweet spot in the center for the pier that is 3 feet deep from the dirt elevation, giving me a total center depth of 50 inches, of the hardest concrete and rebar mix possible.
After the concrete was allowed to setup until 19-Feb-06 (5 weeks), I did a strain gauge test with a vibration test. The result was as expected. I had a total deflection of .0001 inches with a dampening factor of less than .002 seconds. Meaning this puppy isnít moving. The test consisted of dropping a 100lb weight from 5 feet onto the edges and then the center. I then did a low level test and had 6 people jumping up and down on the pad as I was measuring the vibration and frequencies.
In addition I also set into place one 1.5 inch and 3/4 inch schedule 40 electrical PVC from the pier to the west wall. The 3/4 inch runs from the pier location to the house to pick up electricity. I decided to use a wireless network, so no CAT5 or CAT6 Ethernet cable is required.