Samtheeagle's Nest

[samtheeagle]

Many thanks for the advice Bizibilder. I figured I was probably being rather hopeful with my initial plans So much more wood and more support points required. I'll have a think about whether that's still a good option, or whether an alternative approach will be required. Hmmmmms...

Thinking about the colour and the summer heat, I did notice that the stainless steel sink at work was very hot having been in direct sunlight through the window, so I agree, that colour doesn't seem to be too much of a factor. As far as heat was concerned I was toying with a 120mm pc case fan or some such that can be positioned in an appropriate way to aid the venting of hot air from the obsy. But that's a nice to have feature when the thing is built! Let's sort out the foundations first eh?

[samtheeagle]

Random thought... What about if I put some breeze blocks at strategic points under the timbers to provide load bearing capability? Sound reasonable? Or is the crazy simplistic idea of the complete novice builder?

[Bizibilder]

Should work Ok - just use some of that black plastic damp-proofing strip, sold by builders merchants, to ensure dry timber by placing some between each block and any timber in contact with it.

You will need some way of securing the shed to the ground - they behave like big sails in a wind! Normal garden sheds are full(?) of heavy stuff to keep them in one place - observatories tend to be "empty".

[samtheeagle]

You will need some way of securing the shed to the ground - they behave like big sails in a wind! Normal garden sheds are full(?) of heavy stuff to keep them in one place - observatories tend to be "empty".

Yeah, damp-proofing membrane is firmly on the shopping list. And as for securing goes, I'm still intending to have the four corner posts concreted into the ground for anchoring purposes

So supporting breeze blocks, I presume I should lay them on a bed of hardcore / sand, like laying paving slabs? I don't want them sinking down into the dirt too much over time.

[Bizibilder]

Maybe support on block which are themselves on paving slabs? The larger the area of a pad the lower the pressure on the ground and hence less likelyhood of sinking.

Oops! Meant to say this a while ago - If you go the metal shed route forget using the metal shed sliding doors! They are all but useless even with expensive metal angle bracing. I know I tried it. Eventually I replaced mine with a wooden frame of 4x2 timber and made a door out of an outer and inner layer of 6mm marine ply and a frame of suitable timber. If you are careful it is quite easy to do and you end up with a door that works and is far more secure than the original junk metal ones. The cost of building the door, including all the ply, wood and door furniture etc was considerably less than the original cost of the metal angle bracing/locks/nuts and bolts etc!!

[samtheeagle]

Yeah, cheers for the heads up, I did notice that the doors seemed really flimsy... I was planning on bracing them in some way, but a total replacement from the start could well be a good idea.

The thing with the Yardmaster 108GEYZ that I'm eyeing up is that it seems to have a rather large double door arrangement, 120cm wide. In fact the 108GEYZ is kind of annoying in a number of ways. It's the perfect size for me, but otherwise it's all awkward! The doors are on the 10ft side, which is not really what I wanted. My plan was to have the obsy oriented east to west along the longest dimension, with the door on the eastern end. Then the roof would roll towards the east. But the 108 will have the doors facing south, which is the direction that the rain tends to drive in from. Not ideal. That door arrangement also means that the roof will roll off to the side, towards the east, and I don't know how that's going to fit in with the wheel runners having to pass over the top of the door frame? It's a deviation from yours and the Linnhe design, and I'm taxing DIY skills enough already.

As much as I'd like the 10x8 dimensions I'm seriously looking at the 89GEYZ, as it does appear to have the door on the shortest edge, which would allow the roof to roll forward over the doorway to the east. The door would be better protected from the elements that way. I'd probably add a couple of panels on the exterior to form a basic porch, as the door does seem like an obvious leaking point. And the doorway on the 89GEYX is only 102cm, so not quite such a big beast.

So many decisions!!!

[Gina]

Hmm... that's the problem with converting a shed. I looked at probably dozens of sheds of all sorts, mostly on line, with the initial thought of modifying for an observatory. I looked into what would be required to modify them as well as having something reasonable to start with. The only sort that looked do-able cost between 1000 and 2000 pounds and would still need money spent on the mods. So I went for a self-build and although it was very hard work, I've never regretted it. In fact I'm extremely pleased with it

[Bizibilder]

Running the roof off on the door wall is no problem at all if you have an internal wooden frame - all four walls are of equal strength. In my own design the frame is identical all round the runners are simply screwed to the top of the frame, I could just have easily put the roof on to slide "sideways". The only changes would be the weather planks on both sides but these are above the height of the door opening so could go on in any orientation.

As for rain and doors - I have a solution - the porch! Seriously, the "porch roof" on mine prevents 99% of all rain from reaching the door. Its only in serious horizontal rain that any actually hits the surface of the door and with a proper drip on the bottom none has ever got into the observatory.

The door width is actually an advantage. If you put a 4x2 frame into the opening it will use up about 120mm of the opening leaving about 108cm. Its quite useful to have a "wide" door as the doors are not that high and lugging in flight cases/computers etc when wearing winter wollies/coats etc can be quite a struggle! If you are worried then a double frame thickness will soon get the door under a metre wide.

[samtheeagle]

Well that's good to know, cheers gov So that just leaves me sweating over the driving rain... I'm particularly sensitive about this issue as I've spent a lot of time trying to sort out the leaky garage since we bought this place! Like I said before, the rain tends to blow in from the south, and I found that it would penetrate straight through the breeze block wall. I've had to replace rotten boards, re-position the guttering to make it drain correctly, dab roofing bitumen to seal the edges of the metal roof sheets and last but not least apply multiple coats of paint to the exterior. Still, thus far it's dry as a bone

[samtheeagle]

Here's the second revision of my obsy base. I've added a lot more support in now, hopefully it's enough. I'm not planning on doing much jumping about in there So what have we got? More flooring joists, now spaced approxiamtely 500mm apart, and the addition of a number of breeze blocks that will be placed below the joists to give added support. I'll dig the turf off where the base will be, put down weed matting, and then pack down a thin layer of ballast / sand / gravel mix for it all to sit upon.

As previously mentioned these things can act rather like sails in high winds, so how much of a conrete plug am I going to want on each corner? Given my lack of building experience I'm working in units of 25kg bags of just add water mix 1 bag per corner, buried in the gound should be pretty solid, but two could be better? And I've found these alternative post supports: Bolt-Down Post Support 75 x 75mm Pack of 2 | Screwfix.com Do they seem beefy enough?

As it's currently laid out my pier is about 650mm away from the edge of the shed. I think this is adequate space, enough to walk around it to make adjustments and whatnot. I guess I just need to consider how far out the counterweight bar and my scopes will protrude. I should prolly consider scopes I might like to buy in the future too... How long is the Tal 100RS?

[Bizibilder]

Those post holders seem better! When considering your scope size (especially a refractor) dont forget to add a foot (at least) to provide for focusser extension plus barlow plus webcam etc I reckon on my ED120 that set-up adds a foot to the length!

[Tinker1947]

I would go with 4" X 4" posts in the 4 corners with the post in the ground 2' down plus underneath a bed of gravel about 6" thick, then build the rest of the Obby using 6" X 2" connecting the 4 corners, plus your concrete blocks as extra support, it would be a bit more expensive but will be there for a very long time...

[Gina]

I think anything other than oak or teak will rot pretty quickly in the ground. Better if surrounded with gravel to help drainage. NOT concrete, that rots wood quicker than anything.

[samtheeagle]

My plan is to pour some concrete blocks into the ground, to which metal post holders will will be bolted. So the posts wont be in the ground or concrete, all above ground to keep things dry

[Gina]

Yes, seems a good plan to me

[Bizibilder]

Tanalised timber should last at least 30 years in contact with the ground. Which I assume means allowed to get wet regularly but not be underwater - if you see what I mean.

[samtheeagle]

Aye The garden is pretty damp, it's considerably more moss than it is grass! So I'm definitely going to have to be careful as far as rot and moisture rising into the obsy once it's complete. Hence the above ground posts and a good quality vapour membrane.

[samtheeagle]

Another base option is of course laying paving slabs. I'm not going to pour a load of cement, but laying a paved area is a possible option, certainly a less permanent one. Working around where the pier is could be a bit of a faff, but looking at how complex my raised wooden frame is getting I'm wondering if paving could be a good way to go? I could then bolt the shed directly to the slabs, and lay a wooden floor on top of that. I'm just wondering about sealing the edge of the shed base to the slabs... Would the gaps between slabs cause me grief? And damp proofing, would that be placed below the paving?

One other important factor I need to decide is how much room I need to allow around the sides of the pier. I'm thinking 3ft clearance should be enough to prevent collisions during slews.

[Bizibilder]

Clearance round the pier can depend on where you are standing in relation to the door! Trapped by a scope in a dark place with guiding on and the first sub gathering photons (Not that I've ever done that, of course )

[Astrokev]

Another base option is of course laying paving slabs. .

As another option, favoured by some - have you considered building a low wall with a base plate and hang the joists off that? THat would give improved protection against rising damp.

Kevin

[samtheeagle]

Trapped by a scope in a dark place with guiding on and the first sub gathering photons (Not that I've ever done that, of course )

Heh heh Even not having an obsy yet I can understand that! I have found myself wedged between the scope and the fence not sure if my next move is going to rip out all the cables

A low wall probably falls in to the a bit too permanent domain, so that's out along with the concrete base I think.

[George]

Sam here's a good link on a metal shed/observatory conversion.

Linnhe Observatory: the shed section and frame

[samtheeagle]

Cheers George, I already found that one via bizibilder's info as I think it was his inspiration. That's why I'm happy with the metal shed approach, plenty of reference material to refer to when I find myself a bit stuck!

This weekend, when I'm outlawed from my own home (the wife is hosting a hen party ) I shall visit some DIY stores & garden centres to get a better idea of how big these sheds are in the flesh. I've been laying tape measures out all over the shop trying to get a feel for the various sizes, but I could do with standing inside one I think. 10x8 is the maximum allowed by SWMBO, but if I can get away with an 8x6 that would be a lot less intrusive. My needs are modest after all.

[samtheeagle]

A monumental decision has been made! I've settled on the shed I'm going to buy...

Yardmaster Double Sliding Door Apex Shed 7' 10" x 9' 2" x 6' 3" | Screwfix.com

I've been talking it over with the old man and he's very much in favour of a solid concrete base I'm still not keen on the idea, but I understand that it would be a whole lot simpler than my other schemes. I am starting to entertain the following idea, how about a concrete base that is say 6 inch wide outline? Just enough to affix the shed to. Then I'll have a suspended wooden floor, which I'd build over a full concrete base if I were to do it that way.

I like this idea. It will be solid, level, easier to make, and require a lot less concrete. So then, who's going to shoot it down as a really bad idea?

[Bizibilder]

I would still suggest the full concrete base - 'tis simpler and cheaper in the long run.

When building my own obsy I also considered "resale value" should we move (in many years yet, I hope!). The solid base is, of course, an exellent base for a greenhouse, summerhouse, bar-b-q, jacuzzi, garden seat, childrens sand pit (with low walls added) etc etc....

The pier base on mine is about 1" below the main level so if I cut off the pier securing bolts I can easily "level off" with a bag of ready-mix and no-one would ever lnow the obsy had been there.