Gina's Observatory - The Build

[Gina]

The purpose of this thread is to chronicle the actual building of my observatory structure.

The other thread will be devoted to the design and discussion thereof, once I get this thread up-to-date.

[Gina]

Let's see if this works...

The site before any work was started :-

http://stargazerslounge.com/

[Gina]

This was the site after my first (abortive) attempt at building a pier. I changed my mind about the size and position of an observatory and the pier construction I'd started was in the wrong place. Lesson here - make absolutely sure you're digging the hole and pouring concrete exactly where you want the pier.

My weather station Stevenson Screen and mast can be seen in the background. I've moved the rain gauge out of the way ready for preparing the site.

[Gina]

Digging out the site for the foundations :-

The ground is on a considerable slope so to avoid having a very high "shed" (with steps up to it) the ground needed excavating to a depth of 18" along the north side and about 10" along the south side. I'm using some 8" x 3" beams we bought in a second hand timber sale. They were main roof beams from big sheds and well seasoned.

There weren't enough of these to use as joists but they could provide strong support for joists on top and only need supports at each end. They weren't long enough to run the length of the building so were placed crosswise. We had 4 of these but one was flawed so I used three. This meant a length of about 6-7ft (2m) between supports for the joists.

I dug six holes some 12-15" deep and 18" square to take concrete foundations for the beams. Photos showing that later...

I used a Rotavator to break up the soil to excavate the main area and carted the soil away in transport box on the back of the tractor. The photo below shows the soil piled up into heaps ready to take away. The aborted pier diggings can also be seen.

[Freff]

Looks very interesting Gina. I'm amazed you can find the time to all that you do.

Are you closing the other thread now this has started.

[Gina]

Looks very interesting Gina. I'm amazed you can find the time to all that you do.

The housework suffers a bit I do fit it in with other things though, which is why there has been such a delay. I had some work to do on the outside of the house.

Are you closing the other thread now this has started.

No, keeping that for design issues and discussion of problems and design changes.

BTW... I presume you can see the pics alright. My web hosting seems a bit funny with file sharing so I'm using PhotoBucket

[carastro]

I've been watching this on the webcam, you're making some progress over the last week or so. Hats off to you doing this all yourself.

Carole

[Freff]

BTW... I presume you can see the pics alright. My web hosting seems a bit funny with file sharing so I'm using PhotoBucket

Yes, no problems viewing the images..large but no problems.

[Freff]

No, keeping that for design issues and discussion of problems and design changes.

I contemplated on having multiple threads starting with The Pier, then one for the main structure build and finally one for fitting out, electrics etc.

But then I got to thinking, I'm going to be buzzing about here like a blue bummed fly trying to keep up. So only the one for me I think.

[Glen]

Just had a sneaky peek of the cam Looking good. bet you can't wait to get out there.

Wish you luck on the build

[Gina]

I've been watching this on the webcam, you're making some progress over the last week or so. Hats off to you doing this all yourself.

Carole

Thank you Carole It's a BIG project but I think I'm on top of it

[Gina]

Yes, no problems viewing the images..large but no problems.

Good I'll make sure I don't post any full size pics then. I'll scale any BIG ones to around 1000 pixels wide. Full size is around 4000 pixels wide.

[Gina]

I contemplated on having multiple threads starting with The Pier, then one for the main structure build and finally one for fitting out, electrics etc.

But then I got to thinking, I'm going to be buzzing about here like a blue bummed fly trying to keep up. So only the one for me I think.

I had a separate thread for my first pier build but then decided it wasn't in the right place, so started again. I think it works best if you have one build thread - it's often difficult to decide just which thread some things belong in otherwise.

Having produced a lengthy thread mainly on the design of my "shed" (with the help of my friends ) I took a suggestion of starting a new thread for the build proper. We'll see just how well this works out in practice

[Gina]

Just had a sneaky peek of the cam Looking good. bet you can't wait to get out there.

Wish you luck on the build

Thank you Glen Yes, I am dying to get out there

[Gina]

Here's the soil removal. The red box at the back of the tractor lifts up on hydraulics, so you can have it on the ground and push soil into it, then raise it up and cart the soil away. In this case we wanted soil in another part of our property so didn't need to hire a skip or anything to get rid of it. I used the very substantial safety guard on the rotavator to push soil into the box Saved a lot of shovelling

[Gina]

This next photo shows a deeper excavation in the area of the pier base to lessen the depth of digging by hand. It also shows a problem I had at that time with rain making the diggings muddy and the soil very heavy and difficult!

I bought a large tarpaulin to cover the building later in case of rain and decided to try this to stop some of the rain forming mud in the workings.

Unfortunately, in spite of doing my best to arrange that the water could flow off and down the hill, it didn't and formed great big puddles (ponds) in between the supports.

And here's the pier hole dug out by hand another two feet lower. By this stage, digging well down into the solid clay level. Hard going but a really solid support for the concrete pier base.

While on the subject of pier hole and rain...

[Gina]

In addition to the pier base hole (about 3ft deep and 27" square), I dug six smaller holes for the foundations to support the floor beams, as mentioned above. These were about 15" square and 1ft deep. Here are photos of two of them, one showing the beam end.

[Gina]

This next photo shows the three beams in position over the six holes, after being cut to length. One of the trestles used to support the beams for sawing can be seen too. The poor quality is because it was a part of the webcam image. The rain is evident from a couple of water droplets on the window of the waterproof box containing the webcam.

The webcam was in a different place and pointing in a different direction when the image below was captured, from where it's pointing now (more towards the south then).

[Gina]

Ordered 2 giant bags of ballast and 12 bags of cement to suit, for making the concrete for the pier and the six floor foundation blocks. Thought half that might have been enough but wanted to be sure. Also we had a few other jobs requiring concrete.

In the next photo five of the six floor foundation blocks have been poured, though only the nearest two can be seen clearly under the beams.

The piece of timber on top of the far two beams was used in conjunction with a spirit level to make sure the tops of the beams were all on the same level. The left hand far support being the last to be poured before this photo was taken. The spirit level was also used to make sure the beams themselves were level.

[Gina]

Here's a couple more photos of the beams and supporting concrete including a "canine inspection"

[Gina]

Following pouring the concrete for the floor supports, the preparation for the pier and base. Base and pier were to be poured all in one day - not giving enough time for the concrete to set between pourings from the mixer.

The bottom part of the pier base was held in by the soil but the top needed shuttering. Here I rummaged round for anything suitable. Mainly pieces of wood but I also used an old radiator that happened to fit one side just nicely. A couple of pieces of wood held it in place.

This next photo shows the side shuttering plus the rebar rods to reinforce the concrete. The four almost upright ones go right up the pier itself to reinforce that. The bars were hammered well into the sub-soil for extra strength and rigidity.

[Gina]

Because pier and base were being poured all in one go without letting the base set first, it was necessary to stop concrete flowing out from under the pier tube, so top shuttering was needed. I used an old piece of half-inch chipboard with a round hole cut in it for the pier. This was reinforced with a couple of pieces of wood and arranged to be screwed down to the side shuttering to hold it against the concrete pushing upwards.

Here is the top shuttering in place and also showing the pier rebar, held together at the top with a jubilee clip to keep them in place during concrete pouring. The string carried a plumb-bob to get the rebar in the middle of the pier all the way up.

[Gina]

To take the mount and at the same time, further reinforce the concrete, there are four 16mm threaded rods. I drilled a block of wood with four holes to space out the rods and a centre hole that took the top of the rebars. The lower ends of the rods were attached (temporarily) to the rebars with cable ties. These were just to hold the threaded rods in position while the concrete set.

The bend at the bottom of the rods are to stop any possibility of them pulling out or turning in the concrete.

[Gina]

Because it would be very difficult to get concrete past the wood, I replaced it with stiff galvanised wire - heavy duty fence wire - adding the wire while the wood held the positions, then removing the wood. The gaps between the pieces of wire and around the outside allowed concrete to be trowelled into the pier tube (more of which later) and in between the rods..

[Gina]

This next photo shows the container for moulding the concrete pier. I had no luck finding what I considered a good size pipe to form the pier (a couple of suitable pipes have since become available) so decided to use a 7" cardboard postage tube but with plant pots to widen the pier at the bottom where the stress was greatest. I managed to find two plastic pots which fitted nicely together and with the smaller one fitting the inside of the cardboard tube. This increased the diameter of the pier to 12" at the bottom. This photo shows the pier container parts fitted in a hole cut in the top shuttering of the base. I cut the bottoms out of the plant pots, of course

To hold the pier assembly in place and stop the plant pot dropping down, the lip at what is normally the top of the pot, was held up against the chipboard with a couple of pieces of wood, themselves held by wood screws down through the chipboard so that they could be unscrewed after the concrete was set, to allow the chipboard to be lifted off, leaving the pot in place.