Raising a Cylindrical Observatory

This is Part III in a series.

Part I detailed my original questions (boy was I green back then) and all the foundational concrete work. It can be found here: http://www.astromart.com/forums/viewpost.asp?forum_post_id=355146.

Part II detailed the fabrication of a timber "kit" which was partially erected inside to fit everything. It can be found here: http://www.astromart.com/forums/viewpost.asp?forum_post_id=365122.

This part will describe the erection of the "kit" and the assembly of the dome. (Well, we'll see how long this one runs. Maybe the dome will end up as Part IV.)

This historical observatory in Armagh has become our inspiration.

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A trilogy of epic proportions! 8)
Hope all goes well.

The "kit" went up like a snap. First we stacked a bunch of bookshelf off-cuts under the bottom ring (so we could screw up through the ring into the studs), and then attached the doorframe and 8 or 10 studs. Next the top ring went on, and then the rest of the studs.

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The floor joisting went in a few days ago, but the digital camera then got boarded up inside.

(The angle bracing is temporary until the building is skinned.)

I've since put some herring bone struts in between those joists that didn't have bridging for the post or stairs, but they didn't make the picture.

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In between the torrential rainstorms we've been getting, I managed to get out and skin the building with two layers of 1/4" WBP (joints staggered) and a layer of Solitex roofing felt. I ran out of roofing felt about 6" from the top, but that's behind the tarp for now.

(That's my buddy Paul trying to escape the picture on the left.)

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My pad isn't quite circular. (If you go back several pages, you'll see that I used wooden stakes to hold the form. Short sections of rebar probably would have been far better -- they don't tend to get deflected as much by rocks, etc.)

Anyway, I'm putting a lead skirt flashing around the bottom of the walls and over the pad, so I used a cold chisel to knock the top edge off the pad where it was quite proud. This picture shows the edge before trimming.

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Since the "vestibule" design was arrived at after the pad was poured, it overhangs the pad by a bit. While it's only a couple of inches, it would leave two triangular ingress areas for rodents. So I framed and poured a bit (a very small bit!) of a step.

First the damp-proof course was extened by siliconing a bit more plastic to the existing, and then 4 concrete nails were pounded into the edge of the existing pad to act as rebar between it and the step. The step was framed in 2x4s, and then filled with concrete hand-mixed in the wheel barrow. It was finished with a steel trowel several hours later.

This picture is several days later. The form has been removed from the step, and the lead skirting trimmed around the vestubule up to the door.

-- Jeff.

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We're nearing time for plastering, so I'm going to need a different solution for temporary weathering. I'm going to put together a simple peaked roof with scrap lumber and OSB, and then cover it with the same tarp (but it will at least be up out of the plasterers way).

But I'd also like to get the inside painted long before the scope goes in so that the paint has plenty of time to dry/outgas. Since the floor is too close to the temporary roof to install it with the roof on, the decision was made to remove the tarp, put in the floor, and then add the temporary roof.

Here are the scrap-lumber trusses for the temporary roof.

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Well, it's a bit unsightly, but it will allow me to plaster the outside, and my dome should be shipping in the next week or so.

It's been raining cats and dogs here. There are literally puddles of standing water in the field (and it's not like the field is in a low-lying depression). I'm trying to paint the inside, but with all the humidity, I can't get it to completely dry out (and I don't want to seal in the moisture with the paint). I put a heater out there tonight; we'll see what tomorrow brings. (ed. -- actually, I forgot to post this last week -- "tomorrow" has come and gone, and another day as well before it dried out)

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I spray-painted the ground floor walls and ceiling a light blue. This was a grueling task from which I emerged blue myself. The floor is also entirely blue, even though I didn't paint any of it!

I'm not terribly happy with the color, but it's not going to change now. :S

You can also make out in both pictures the 3/8" x 3" plywood rail rebated into the studs to keep them from twisting.

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