Thinking stage....

[jambouk]

I have been pondering the idea of an observatory for some time now, and just want to take the plunge. I don't have the best vistas in the world, and I have light pollution from the city a mile or two away to the north, but I can't see me moving house soon and just want a permanent set up. I am not [yet] into fancy imaging, but I do like planetary and lunar imaging, and the hassle of setting up (and the British weather) means I get out there less than I would like to. I've explored the option of just a permanent pier, but I want to leave a telescope permanently mounted with all the leads and dew stuff attached, and to be able to go at the drop of a hat. I don't want a pod or domed roof.

I've looked through the David Artitti book which has helped answer some questions, but I have others.

I'm no DIYer, which is a key consideration here.

Attached is a rough outline of what I'd like (the scales are quite far off, but it hopefully gives an idea). An 8ftx8ft observatory with a roll of roof, and an attached 6ftx8ft warm room, with one external door opening into the obsy, and one door from the obsy into the warm room. I'd also like a window in the warm room I think (looking south west). The roll off roof would roll north west over the warm room, and towards the house, and overhang the warm room by 2 foot or so. There is my boundary fence to the east of the observatory and the neighbour has a shed the other side of that fence; I'd leave a 0.5m gap between the obsy and the fence so to get down the side and to be able to paint the fence and the obsy.

I now have a pier in my garage, so just need four bolts sticking out of the concrete base to screw it onto.

My questions / worries are numerous but include:

1. Getting power to the obsy. I own the fences in green, and these are all being replaced in two weeks with concrete pillars and concrete boards along the bottom and new wooden panels, and I suspect I could ask the fence blokes to bury two pipes between the lean-to shed and the proposed observatory site to subsequently channel wires through, but I don't imagine they will be digging a trench 600mm deep...

2. I can get someone to build and assemble the observatory (see point 3), and I can probably get someone to do/help with the ground work to lay a rim of foundation for the walls (see point 4), and a concrete block for the pier to bolt to, but I am just worried when the observatory installing people arrive that the wooden structure won't match the concrete footprint or the pier foundation will be too low (see point 5).

3. Who to get to make the observatory?  I like the look of this sort of one http://stargazerslounge.com/gallery/image/21700-warm-room-end-windows-in-roof-rail-supports-fitted/ as it has a nice high warm room ceiling, where as the Ian King one I went to see had a much lower ceiling in the warm room, though it had a more conventional pitched roof which looked more "shed like" (see other image attached).

4. Does the foundation for the observatory and warm room want to be a) one massive slab of concrete, a rim of concrete foundation just under the walls and a separate sunken block of concrete for the pier, c) something else?

5. If I were to move house, I could leave the wooden structure in place to be used as a shed, but I'd want to take the pier and disguise the hole in the floor; would I just cut the tops of the bolts off and put a wood panel in the hole in the wooden floor?

6. Ventilation. I appreciate in the UK it is damp for lots of the year. What is the proven method to prevent this damaging the kit? Air vents, heaters, fans, or a totally air tight unit and use electric dehumidifiers?

I have visited one astro-friend and his roll off roof observatory, and this has motivated me to get on with my project (http://stargazerslounge.com/topic/165469-robs-obsy-build/?hl=%20rob). I plan to look at a few more local projects to get any additional ideas and learn from their experiences before I sign any cheques, but I would value ideas / experiences / suggestions from SGL with regards my early thoughts and concerns.

Thanks.

James

[catman161]

Looks like a great project. Looking forward to following this. Exciting times for all involved, I'm sure you'll agree

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[jambouk]

Looks like people advise keep the power cable and data cable trunking >6 inches apart if they are buried. Something else to consider.

JD

[leelee970]

You will not regret building an Obsy. It completely changed my hobby.

I now look out the window, see a clear patch and dash outside.

Within a few minutes I'm viewing the heavens. If it clouds over I can quickly shut it all up.

Lee

[r3i]

Hi James,

Best of luck with your project.

In answer to some of your questions:

1. Instead of 2 pipes (presumably 1 for power and 1 for network cable), have you considered using PowerLine adapters?  I use them and they work really well, and this would simplify things as you'd only need to lay a single cable.  If possible I would feed the cabling through the pipes as they're being buried to avoid any snags that might occur when trying to get the cables through later on.  Also you might want to consider using armoured cable instead of normal cable within a pipe.

2/3. Can't comment as I went down the DIY route - you sure you don't fancy it?  Go on, you know you want to

4. I didn't like the idea of having a huge concrete slab in the garden so my observatory is built upon decking, which is fixed to the ground using anchor posts.  One benefit of using these was that it was easy to level the decking as there is a small gradient in our garden.

5. Yes, that's what I'd envisage doing if we ever moved.

6. I think damp countermeasures is one of those things you need to play by ear once you're all set up. My scope room has quite a bit of natural ventilation and there's plenty of wind around to keep a good airflow so I haven't experienced much in the way of damp. I do however run a small dehumidifier in the warm room together with a tubular heater. I did notice that the scope room got quite hot during the summer months so I've fitted a solar powered vent fan to create additional airflow.

[jambouk]

That is really helpful stuff, thank you

I'm not sure yet what data cables i need, probably just ethernet. I've got powerline to one room in the house, and i'm unimpressed with it inside the house, but if it went to the obsy, in a small enclosed area it may be more effective, i'd not thought about that; i think there are issues if the power in the obsy has it's own circuit, but i've not thought about that / had advice on that yet. I thought two pipes 10" apart underground would future proof me a bit.

I'm going to see two obsy's on monday so hoping to get some more ideas then.

Thanks for the thoughts and comments, really helpful.

James

P.s. Does the warm room need insulating?

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[malc-c]

James, hope the following helps.

Footings:

This will depend on the design of the observatory.  Most sheds are sat on top of a solid slab, and quite a few builds follow this principle.  In my build I opted for a suspended floor, and thus built a 4 course dwarf wall on a footings.

This has the advantage of allowing a nice thick layer of insulation under the warm room flooring.  However as far as I know most commercial shed shops or even commercial observatory suppliers don't cater for this sort of arrangement.  You might therefore want to look at getting a builder to undertake a custom build if you are not able to do it yourself.  If you opt for a suspended floor design, you need a couple of air bricks in the wall to allow for air circulation and preventing damp forming.  A DPM was also placed in the wall at the second course.

As far as ventilation is concerned, my design is such that air can enter the scope room under the sides of the roof section and have had no issues with condensation on the equipment after two years, but I do need to add some ventilation in the warm room as condensation formed on the sides of a cabinet and over time saturated the carpet tiles.  But this was one of the wettest winters we've had and the observatory was not used for some time.

If you intend to run mains power to the observatory armoured cable is a requirement for a permanent installation.  I would consult with an electrician if in doubt, but you may be able to get away terminating it on a fused spur rather than a dedicated trip in the consumer unit.  Data cable can be laid in a tube buried under the ground, or surface mounted along a fence.

My build thread is in my signature, if you have a few hours it's worth a read (as are some of the other build threads in the sticky at the top of the observatory section) 

[jambouk]

Again, thank you Looks very impressive/sturdy/permanent.

Is the brick course allowed for a temporary wooden garden structure, or would that require permissions?

I'm conscious that i may want to move in 5-10 years, and i may even need to remove the structure to get interest in the property to sell it; we have no idea what the house market will be like in 10 years time. So i'd prefer something less permeant above ground level. A concrete trench around the exterior walls and the wall between the scope room and the warm room would be relatively easy to cover up again with grass if it was slightly lower than surrounding grass level (but drainage issues). The ian king observatory had a suspended floor, the floor joists sat on the concrete slab or spanned between the trenches at opposite sides; i liked this idea.

I've dedicated some time next week to looking through the threads on sgl, as well as looking at these real life garden obsys close up to get inspiration.

As i said before, this isn't my area of interest or ability; i'd rather just pay someone to sort it all out after i'd shown them what i want, but there is no one company who seems to be able to sort out all the various facets of the job (ground work, piping, wood work, electrics, roofing... Well not for under £5k anyway.

Thanks again for your comments and direction; really helpful.

James

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[malc-c]

James,

The wall is a single skin so can easily be removed - My structure just came within the constraints of not needing planning permission.  The footings are between 6" and 18" deep and could easily be removed or taken down to a point where top soil and a lawn laid over the top - mind you removing the 1 cu mtr block and pier would need a small crane !  However we are not planning on moving which was why the construction was done in this way.

The Ian King observatories are new to the arena but do look as if a lot of thought into the design, not sure what the cost would be for a large scope room / warm room option would be.  I also noticed that the internal timber was un-treated, something that I would have them address.  Not knowing the construction method they use, but unless the joists are 6" x 2" I wouldn't suspend the floor on blocks as the floor would probably flex.

In answer to one of your other questions, yes its normal to insulate the warm room throughout.  I've used 50mm under floor, and 25mm in the walls and ceiling.  The scope section has no insulation as you want the scope to be as near to the ambient temperature as possible so you don't have to wait for the scope to cool down etc.

As suggested, I would get a couple of quotes from some local builders and compare them with a similar quote from Ian King.  You may find it's a lot easier to project manage a build when it's custom made on site then having something off the shelf so to speak.  I would of thought that you could get a 2.2m x 4.8m structure built for under £4K by a local builder, including the footings

[andyboy1970]

I have just sold my house, I took the obsy down and only the concrete pier is left.

The cubic meter of concrete is below ground level anyway.

Nobody even asked what the pier was.

If someone had wanted to buy and insisted I remove the pier I had the angle grinder on standby!

[jambouk]

Thanks

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