Construction started in May of 2005, was delayed during the month of June while I was at the Aspen Center for Physics, and was finally completed in August of 2005.
The structure is free standing on concrete pier blocks, and situated to put my lowest wall toward the most open part of the sky I have on the property, approximately toward the southwest.
There were three basic parts of the construction: the frame and floor, the walls, and the roof. Here are a few pix of the first (of many) materials run.
Frame and FloorI had no desire to have to sink foundation holes for the posts and pour cement. The holes would have been hard to dig (I called several companies in State College about having it done, but several were downright rude -- that's why I don't call people on the phone. If you don't have a website, then I don't want to do business with you), and it was going to take a LOT of concrete.
One of my books on building sheds suggested a floating foundation, with surface level footings on gravel beds. I found concrete pier blocks at a local hardware store, meant for footings on decks, and these worked great. They are slotted to receive with 2" dimensional lumber, or a vertical 4x4. Since there is a slight slope on the site, I dug the gravel beds, placed each pier block, then using a laser level from the highest corner worked out the heights all the way around the frame to make it level.
I used one pier block at each corner of the observatory for the main vertical posts, all bound together by 2x12 beams, with 2x8 joists running under the floor. The joists are supported by joist hangers, and have individual 4x4 footing posts on pier blocks under their midpoints.
The floor is 3/4 inch plywood, screwed down to the joists. I left a 2 foot square hole in the center, which will have a separate floating frame that the scope sits on. I don't do anything fancy like astrophotography, but this will keep footsteps from jiggling the scope.
WallsI wanted the walls to be low enough to be able to use a Dob without having the scope up on a tall pier and requiring the use of a ladder to observe all the time. Given the horizons around my site, I could have tall walls in the directions of trees. This allows a design where I can stand in the observatory when it is closed, but not compromise my horizons with a large observatory cutoff.
The northeast and southwest walls were squared an connected with a double run of 2x4 that run the length of the observatory; these provide an anchor channel for the 4x4 rail system that the roof will roll on. Single 2x4 run the southeast and northwest walls at the height of the lower wall; these provide an anchor for the frame studs, and also block out the lower part of the wall where the windows will sit.
The southwest wall is the shortest, measuring 40 inches from the floor to the top of the roof rail. The southeast and northwest walls are peaked in the center, following the line of the roof. I wanted to observatory to be light during the day because it has no permanent, electrical connection so the frame for the side walls accomodates preframed windows purchased a a local hardware store. The back (northeast) wall houses the entry to the observatory, which was framed to accomdate a pre-hung exterior house door, also purchased at a local hardware store.
The walls are covered with rough pine siding, screwed to the frame shown above. The worst part was cutting out all the bits to fit around the windows, along the diagonal roof cut, and around the cantilever supports for the rails. The final stage of construction will be to trim all the corners and edges with boards to cover the edges, and varnish to leave the siding with the natural wood tone..