Whinhill Observatory

[Stevp]

I can't resist any longer! Finally I'm getting started on my observatory project.

This has a been a number of years in the planning, mostly because i'm not the kind of the person who is good at getting projects underway in the first place. I've had a few woes over the last couple of the years, perhaps i'll elaborate in the near future in a non-astro thread, one of which has seen me now struggling with even a relavtively low amount of lifting and carrying. So, since my kit got very little use last winter my aim is to get myself up and running with a roll-off-roof observatory to give me a permenant set up.

I have planned said observatory a number of times over in various guises and locations in recent months, but now, i've got a plan, got a location and have broken ground!

I will of course attach photos when i've got something to show, but for now you'll have to use your imagination to visualise a big hole (which I certainly didn't dig myself!) and four sticks marking the footprint. Not much, but it's a start, right?

Here is the plan.

This is being built at my parents house, who are fortunate enough to live pretty much in the middle of a field with little nearby in the way of street lights etc. It's far from a perfect site about with a lot of light pollution from the humber off to the west, but not bad in the scheme of things you could hope for. I've studied many of the threads on here and have come up with an idea that pinches bits from here and there and my plan is hopefully something I can make work.

The plan for the base is to first make a low level deck that is 3m x 4.2m as this suits the timber lengths well. In old money thats around 9'10 by 13'9 and i'll apologise in advance for swapping and changing between the two. So the deck will consist of 5 concrete posts down each of the long lengths and then a ring beam around the outside, from here there will be a suspended floor on joist hangers which will get covered with thick ply to be the floor. From the bottom of the ring beam (tanalised timber) there will be a small hole wire mesh covering the gap and dug a spade or so down to reduce the chances of the wildlife moving in underneath. As I said, the property is somewhat in the sticks and there is no escaping rabbits, rats, foxes etc, so at the very least covering the sides will deter them.
I considered building a dwarf wall around the outside (particularly like Malc-c did, your thread was a huge inspiration!) but have decided against it as the site is somewhat sloped and it will be easier to make up the difference on posts/deck than a lot of extra brick work, plus it isn't directly accessible from the driveway so all materials will need moving manually a fair way.

So, at the moment we have a hole that is around 0.9m in all dimensions and a load of enthusiam, waiting for the guy to come and get the posts in.

One thing that i'm already not clear on after a boat load of research is the use of membranes etc in the floor / deck. So any input is welcome. Since the sides of my base won't be enclosed, other than the mesh wire, it should be pretty well ventilated, buit i'm not sure on whether there is a need (or reason against) putting a breathable membrane between the joist tops and the ply covering.

Comments and ideas welcome. Apologies in advance that this may go on for a while!

Cheers

Stevp

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[triley4]

Hi - Congratulations on starting your build. I started mine a couple of weeks ago - I am following a Heath Robinson ethos with mine. 50 x pondering and imagining what it would look like (I have no plans on paper), 4 x measuring, 1 x times cutting, 1 x daily revising my mental image of the end product and ever increasing complexities I'd like to add.

Like your self, health as much as convenience dictated the need for an obsy - Carrying an eq six and full imaging rig with all its ancillary into the hulo is tough on the fittest of people.

Good question on membrane - Hope some one picks it up. I've bought some thing called builders paper. Hope it does the job.

As well as water tight, from what I gathered it is careful balance of insulation/ventilation/circulation.

I keep saying this but will start my build thread shortly. Will be following your progress.

Ant

[r3i]

Hi Steve,

Best of luck with the build and look forward to seeing lots of progress pics.

I also chose a decking style base for mine, which matched my DIY capabilities (a dwarf wall of the quality that Malc produced would have been way beyond my skills).  Instead of using concrete posts I used an array of fence anchor posts (aka MetPosts), but the result will be pretty similar.  Our garden also has a slight slope and the use of anchor posts made it easy to get the deck level.

I don't have a membrane within the floor but I do have slabs of 50mm Celotex under the flooring of the warm room section to act as insulation.

[Stevp]

Thanks both,

Yes, i've talked myself round and round with regards membranes and seeing the problems that some people get mith moisture I want to try to get it right from the beginning.

Mike, i'm intending the same at this point. Celotex on all sides of the warm room. Have you had any or much issue with damp etc?

Cheers

[Stevp]

Hole!

[saac]

Go for it Steve, while a build is hard work it's hugely enjoyable and rewarding. You won't regret it.  As for damp etc, I don't have any membranes on mine just good ventilation.  After a year in our delightful Scottish climate there is no sign of dampness/mould etc.  That said every build is different and you'll certainly find lot's of good advice on here.  Good luck with the build, you are off to a good start with that hole.

Jim 

[r3i]

Mike, i'm intending the same at this point. Celotex on all sides of the warm room. Have you had any or much issue with damp etc?

Cheers

Hi Steve,

I've had no problems with damp. In all the external walls I have a basic ScrewFix vapour barrier. In the warm room walls and the ceiling I have bog standard rock wool for insulation. Nothing fancy but it all seems to work well.

[malc-c]

Hi Steve,

Nice to hear that my build has been inspirational for you.  To be honest my site is on a slope in two directions,  The trick is to get level foundation, which means that you average the drop.  This way, you have a course of bricks lower than the ground level at the high point, but at ground level at the lowest point.  Provided the DPC is above ground level you won't have any issues with damp rising.  If you do opt for a dwarf wall, don't forget air bricks

I'm not a fan of using mesh as protection.  We live in a town and have two chickens (wifes project) and even with wire mesh secured to the run, with the tails of the mesh buried under 20mm stone chippings rats still managed to get in on one occasion.  Can't say I've ever had any issues with rats / mice in the past three/four years with the observatory.

One thing that you might find is that with a floor on stilts with the wind free to blow under the building, that the floor will soon feel cold, even with good insulation (we lived in a mobile home that was on a slope and the place was freezing until I boarded off the space between the floor and the ground).  Basically you want to treat the walls of the observatory as if they were the inner walls of a Barratt home (remember them !) - using a vapour barrior will stop ingress, but I never bothered in my build, and can't say it's caused any problems, but then I'm using standard expanded polystyreen insulation in the walls and roof void.

Anyway, seems like you are off to a good start.. nice clay soil !! and a really neat hole

[richyrich_one]

Hole!

If the rest of the build is to that standard it will be a mighty fine observatory!

[Stevp]

I was as equally impressed as everyone else with the hole. The guy that dug it out for me is a former grave digger! It's easy to see the skill you acquire through experience!

Thanks for the tips Malcolm. I'll have a think about the sides under the deck, maybe something more solid would be in order.

I'm interested to know about your floor and walls, did you insulate only your warm room (as was my intention) or did you do the whole lot?

There is no escaping the clay around here, the whole area is built on the stuff, if you search for "Mappleton" you'll see the latest example of a cliff on this coast going over in the last few weeks. Thankfully I've got a good few hundred years before I need to worry about a sea view

I was wondering, do people put hardcore/rubble in to the bottom of the pier hole before concrete? or just straight down to the soil. I know ideally you would dig down to a rocky layer, but I might reach Australia if I tried that. My plan is to make a concrete block with a steel pillar bolted to the top, rather than a concrete one.

Attached are the views from the pier location. A few trees to contend with, but also some nice big uninterrupted sky.

Cheers

[malc-c]

Thanks for the tips Malcolm. I'll have a think about the sides under the deck, maybe something more solid would be in order.

I'm interested to know about your floor and walls, did you insulate only your warm room (as was my intention) or did you do the whole lot?

Cheers

I only insulated the warm room floor, walls and roof.  My logic was that the scope room being un-insulated would be at an equilibrium with the outside temperatures, where as the warm room is cooler in summer and warmer in winter by a few degrees (sometimes as much as 6-8c either way)  I used 100mm thick Jablite insulation panels for the floor, and it's proved really good at stopping the coldness coming through even in mid winter (although I now tend to remote desktop from the comfort of the lounge when it's too cold !)

[Stevp]

Thanks for clarifying Malcolm. Thats exactly as i intend to do it.

[Stevp]

Small progress, I now have a pile of concrete posts and a lot of post fix! If the bank holiday weather is forgiving, hopefully I will get a start made with setting the posts. The timber is ordered for the ring beam and floor joists.

[Stevp]

Hi all,

Sorry for the tardy update, i've been making good progress with a lot of help from my bro. I've now got the posts in, the ring beam around and half of the joists fastened. I've stopped with the joists until i get the pier hole concreted up (hopefully this weekend).

Enjoy some photos

[JeremyS]

Indeed, looks like good progress!

Jeremy

[r3i]

Good progress Steve, it looks like you've got a very solid base there.

[Pan Euro]

Great start, have you given any thought to keeping weeds at bay if you are going to leave the sides open.

Ed

[Stevp]

The materials have arrived for the pier block. Well done to the delivery driver pushing his Hiab to the limit to get it over the hedge and dropping it with pinpoint accuracy in a spot he couldn't see!

[Stevp]

Great start, have you given any thought to keeping weeds at bay if you are going to leave the sides open.

Ed

Hi Ed,

I hadn't actually, good spot!

The intention is to put a wire mesh fence around the edges to try to keep the rats and rabbits deterred. Also i'm intending putting a gravel 'path/drain' around the edge that borders the grass. I'll get some weed barrier stuff and cover the ground underneath before the floor gets covered.

Cheers

[Stevp]

Pier hole done! Yesterday turned in to an epic concrete mixing adventure. The hole is now filled with approximately one cubic meter of concrete, which equates two 18 mixers worth. Ready mix would have perhaps been a better idea but it would have presented a lot of challenges getting it to location.

Steve

[Scorpius]

Steve - your build is progressing nicely. Keep up the good work...

[Stevp]

A busy day today.

Me and my brother got the last of the posts in for the base and then constructed most of the frames for the walls. I've not got many pics to share today, just this one showing a few of the frames

More to come tomorrow all being well.

[Scorpius]

Looking good Steve! - I'm gonna need to step it up a notch after the rain or I will never catch up!

Looking forward to tomorrow's pics... 

[Stevp]

Another very busy day today. We've got the frames up!

And another shot that shows a bit better how much slope there is on the garden.

[nameunknown]

Nice roomy build!

A sheet of "Visqueen" membrane (the blue polythene) under the plyboard won't cost much. I have found that some cheaper grades of half-inch ply (like "concrete shuttering") are particularly sensitive to damp/rot and consequent de-lamination. "Marine Ply" is less sensitive, but costs (much) more. If it were me, I'd "Visqueen" the walls as well just under the inner skin (you could then use thin ply or even plasterboard) to provide a vapour barrier and use polystyrene between the wall struts. While you are at it, possibly think about some air vents in/near the floor to help cool-down time and a well-insulated wall around the "warm room".

It's also worth giving some thought to "downstream" uses. Should your parents win the Lottery and retire to the Islets of Langerhans "Summerhouse" is, perhaps, more saleable than "Obsy", so when I built my "glass" sliding roofed affair (four floors up) I put a window in with "stunning view of North Wales" (you can see the odd mountain with binos).

P