Building the shell

I looked long and hard at every conceivable building site for the new observatory on my property near Bear Valley California (the town and not the ski resort). Every site had benefits and pitfalls. The site I ultimately chose was the keeper due to the small number of trees that I would need to cut down. The next best site demanded over 40 trees be removed. The drawback of this site is that it does pick up the headlights from our access road and it can be seen from the same road. I had hoped to keep it somewhat private for security reasons.

I chose a roll off roof design because the temperatures are moderate all year long here and I enjoy being "out" under the stars. The roll of design also provides better cooling to the ambient air. The cooling aspect also dictated a raised floor as compared to a cement slab. The observatory had to be large enough to provide ample space to walk around the equipment and to have a moveable cart for computers and eyepieces. The equipment would reach a height of almost 6 feet so the roof would need to clear it.

I started the project by digging four holes in which I would concrete posts to support the structure. These were intended not only for vertical support but to keep the building from sliding in any direction. Other piers were added for additional support after the floor had been framed. I moved the top layers of soil to expose solid ground. The pier blocks were solidly laid before connected to Our next door neighbor dropped by just as I was finishing up the floor and gave me a hand with the framing. He helped me lay out each wall and frame the north wall. The other walls I set up myself. Notice the door is not capped. This was left open so that a person could enter the structure without bending over. An open door like this required diagonal supports in 4 directions to have any stability. You can see two of them in this picture. After the siding was installed the two visible supports were removed but the two perpendicular to the walls were left in place.

The siding installation was very straight forward around the bottom portion of the building. Then came the top of the building... how to build a 10x12 box on wheels on top of what I had... hmm. I framed the two long sloping sides on the ground, added the siding and wheels. Paul and I then "wheeled" them down from the cabin and propped them up in the tracks. Paul held each one in place while I secured temporary diagonal braces to the floor of the structure.These braces were made of 8' long 1"x2" strips. I screwed a 2x4 in two places to the floor and attached the braces to them. After the diagonal braces were set, I nailed a scrap 2x4 piece on to the outside of the structure connecting the base and roof. You can see two of them in the above photo.

I then installed the roof supports from wall to wall. These were made from 2 2"x6"x10' boards nailed together. I had framed each wall with appropriate "notches" to receive these. They slid right into place and were easily secured. The top walls now stood on their own and seemed fairly steady. I put together a framed wall for the front wall (not visible here) and slid it into place and nailed it in. Major additions were made in this stage. The first thing was to get a roof on the building to protect the inside from the wet weather we have been having. I obtained 2"x4"x14' boards and secured them everey 24 inches from north to south. We then secured half inch thick 4'x8' oriented strand board to the top. Paul insisted that I didn't need this to put a metal roof on but I wanted the increased stability of a strong underlayment.We laid down treated felt (tar paper) on top of the plywood and left the project in the rain for a week. When we returned, the roof proved to be weather tight. The large opening in the south upper side had been covered by a plastic sheet however and had allowed a significant bit of weather in. 

Paul worked on installing the sheet metal he had made as a favor. (Doing computer work for friends does come back to you!).

The tracks were made of sheet metal as well as the custom made skirts around the wheel space. I worked on enclosing the south end (visible above) with a giant door that folds down along the outside of the lower part of the building. The door is "latched" inside with turnbuckles and helps secure the top part of the building together. When the door is opened, the top can be moved off the building. The last part of this stage was to install the posts that support the rails extending north of the building.