Rocky Plains Observatory
- Floor Construction
The floor design called for a straightforward arrangement of doubled up 2x10s to form very solid beams along the 12' east and west floor perimeter, with 2x8 joists spanning the 10' in between. The beams were leveled and nailed into the (6) post mounts that had been set into the concrete footers. The 2x8 floor joists were fastened to the beams using sheet metal joist hangers. I took great care to get the framing square.
After framing, the floor was sheathed using 3/4" tongue and groove waferboard. Sheathing was glued and nailed using ring nails. I also attached 1" foil backed insulation on the undersides of the sheathing prior to installation. This was to act as a moisture barrier and provide a little insulation. If needed, I will cut vents in the ends of the beams later for air flow (haven't done that yet).
An important feature in any observatory is cable management. Being able to easily add or remove cabling is a key point, and I wanted flexibility to change routing in the future. I designed the floor so that cables can be routed underneath two removable panels that simply set into place. Secondary panels are permanently screwed below these panels to seal the cable routing spaces. In this way, I can easily route cabling to the east or west of the telescope, or cross completely under the floor from one side to the other. Above the concrete pier is another panel that will have a 13" hole cut in it for the steel telescope pier to protrude through. The concrete pier and 3/4" bolts are located just below floor level. Another panel seals the space around the concrete pier, with a 1/2" gap all around sealed by foam rubber (floor remains isolated from the concrete pier to prevent vibrations reaching the scope).
I completed the floor in October, and kept it covered by a tarp all winter, while working on the roof components.
- Wall Framing
After a winter of completing the roof pieces (see Roof Fabrication) and working out all the remaining final design details, spring finally rolled around and warmer weather allowed me to complete the framing. Weather in Colorado is extremely variable, so when I saw a span of several promising days, I jumped in and got going (one day in May while I was putting down the roofing felt we went from a calm day of 80 degrees to the high 30s, light snow, and 70MPH wind gusts - all in the span of under 2 hours!).
The wall framing was very straightforward, using 2x4s on 16" centers. I built and sheathed the walls one at a time flat on the floor, then tilted them into place. Having a square floor really paid off here, as everything came out extremely plumb and square. Sheathing (3/8" OSB exterior grade) was glued and ring nailed (a nail gun came in real handy here). Honey, I just Have to Have that new nail gun... Be sure to leave small (1/16") gaps between sheathing seams, to account for expansion/contraction. When done, I wrapped the building with a moisture barrier (similar to Tyvek). I told my neighbor I was fond of pink and was going to leave it that way...
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