Category : Observatory Build

Observatory Build – Filling The Hole

Today the hole was filled by an AnyMix concrete mixer. I spent a while looking into how to fill the hole, whether to manually mix the concrete myself and hire an electric cement mixer and order in the cement and bags of ballast.

But after using some online concrete calculators I discovered I actually needed 2x 1ton bags of sand and possibly something like 13 bags of cement. This price came to about £160 with the hire of the cement mixer, I thought it would originally cost me about £70 to do it myself, but a 1 cubic metre needs more aggregate than I thought.

The 1 ton bags of sand were not too bad price wise, as BuildBase sold them for about £45 each. Anyway I then decided to call around concrete companies and get some prices.

At the time I did not really know what mix type I wanted, as it all seems a bit confusing to me. James at ScopesNSkies recommended a 3 to 1 mix, so (1 cement, 1 gravel, 2 sand).  I was told by some companies that this may be too rich, as adding too much cement would mean the block would crack.

So in the end I got prices for a C35 mix type, although Hanson advised a fibre mix with hair in it.

Hanson quoted about £250, Cemex quoted £206, Tarmac would not deliver to my area, and finally AnyMix originally quoted £167, but after phoning back and saying I was originally quoted £150, they agreed on this price.

Hole with Wood FrameThat was great as this price, was less than what it would cost for me to do the mixing myself, so the delivery was booked just 24hrs before, for a 3.30pm delivery.

My father and I began by building a wooden frame so aid with levelling the concrete. I bought the 2×3.6m 1″x2″ wood from Travis Perkins for about £6.50. We then also used some blue plastic liner to contain the moisture of the concrete. We actually used 2, one inside the other.

Hole with Plastic LinerThe delivery was a bit late and arrived at about 4pm, but the driver was very accommodating and friendly, and we used 2 wheelbarrows to offload the concrete.

Even though the hole was nearly exactly a 1 metre cubic hole and I ordered 1 cubic metre, we still had about 5 wheelbarrow loads left over in the concrete lorry. Luckily the driver decided to get rid of it for us, although with hindsight we could have used it for the footings to go under the slabs. But we had not thought of this and had not pre-dug the space.

Hole Filled with ConcreteNext time, if there is a next time of doing this, then I will pre-dig the footings to be ready for any over supply of concrete.

The concrete went in well, and it was a bit of hard work barrowing the concrete. My Dad levelled off the concrete with a large length of wood and now it’s drying off. Apparently it will take about 1 week to fully set.

Found a Hedgehog in my Hole!

The observatory pier base hole has been empty for a couple of weeks now, waiting for me to get my concrete order set up.

Hedgehog on my spadeWell today I popped out to Travis Perkins for some wood for my concrete frame, and when I came back I found a hedgehog asleep in the 1 metre deep hole. Poor thing must have fell 1 metre, one evening and then settled in, although it does appear that it did try and do some digging whilst occupying the hole. I think it may have been in the hole a maximum of two days.

Anyway, I got it out by using my spade and lifting it out and taking some soil with it, as to not disturb the hedgehog.

Here is an image of the hedgehog still alseep after being set free.

I left him snoozing on the spade, but after returning an hour later he was gone.

Observatory Build – Digging The Hole

This is day three and day four of the observatory build. My goal this weekend was to dig the cubic metre hole for the mount base. I had a 2 yard skip delivered on Friday which cost £60. I also borrowed my dad’s wheelbarrow to complete the task.

Observatory Mount/Pier Hole Now DugI started at about 9am on Saturday morning, and the first couple of spade lengths went really easily, but then I hit the builders rubble level, and this point nothing was going through, not the spade nor the fork. At this point I was ready to give up and visit the tool hire shop for a pneumatic hammer or drill or something! But after a bit of perseverance and actually inserting the fork and then doing a circular motion I actually made it through the rubble and stone level.

This gave me renewed motivation, and luckily by 12noon I had to stop in order to go out to a BBQ. At this point I had dug to a level of about 30cm, so only about 70cm to go!

Sunday I carried on and started at about 10am and dug for most of the day, with a 2 hour lunch break. I ended up putting the parasol and base above me to keep me out of the direct sunlight which help enormously.

I did find the digging now reasonably straightforward, as I went from brown clay onto grey clay which was a bit smelly. Throughout the digging I was also joined by a friendly blackbird looking for food, as well as a bee who enjoyed visiting the new small holes made in the sides of the hole.

The Bottom of the 1 Metre HoleSo at about 5pm the hole was complete, but only after shaving a few centimeters of the sides, as my digging was not completely straight. The sides don’t measures exactly 1m, at some points it is 95cm wide, but I hope this won’t matter too much.

Next I am going to have to fill my hole with concrete.

Observatory Build – Day 1 and 2

This was the first couple of days I actually got started in preparing the observatory base. I have spent a few days browsing websites, talking to astronomy retailers and other observatory owners on the web.

I also drew up a loose plan of the observatory and what number of slabs and aggregates I required. I drew up an image in Fireworks (the Macromedia photo/paint program) which allowed me to draw lines, boxes and circles and move them all around to see what fitted.

Day One

I began my first day by moving the current shrubs in the border out of the way and re-planting them somewhere else, this basically took me the whole of day one.

Once the area was now clear, I then marked and measured out the area of the location of the shed.

Day Two

Observatory Base, Grass Removed and Ready for Pier Base to be dug.Today I took up the turf that was in the way and also measured out the central hole, where to concrete base for the pier is going to be. I have been advised by James at ScopesNSkies to dig a cubic metre for the base, so 1m wide, 1m long and 1m deep.

This is a fairly big hole, so I am considering getting a small 2 yard skip to take the soil. Instead of mixing the concrete by hand, or with a mixer, I am also going to enquire about the cost of getting the concrete delivered, then just using wheelbarrows to take the concrete to the back of the house. I have read that 1 cubic metre is about 20 barrow loads.

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