I'm starting out on what will no doubt be a long and expensive journey, but I'm hoping the end cost will be less that a dome purchase - which can start out at around $5k for something decent.
So, budget requirements led me to plan a skillion roof shed and have the roof "flip" on a simple hinged arrangement. I've obtained a bollard which will form the base of my pier and have to find someone that can machine and weld a steel plate on to that, then an aluminium plate separated by threaded rod for levelling.
I'm a little worried about flexure in the metal, but will just have to leave those worries alone for the time being and get the shed up in the first place, then bolt the pier in place on the slab - which is actually the top of my in-ground water tank.
Some pictures of how it looks now. In a few weeks I'll start to mark out the shed spot and get the family over for a good shed building and bonding experience
Good luck with the project and while I don't want to rain on the parade it seems to me the inground water tank "roof" might not be the ideal foundation for your pier.
I'm not expert and maybe others can comment but most choose a substantial concrete foorting on which to mount the pier. I think the top of the tank, which I presume is less than 200mm thick will be prone to flexure.
Is there a reason why you wouldn't just dig a hole and fill that with reinforced concrete?
In relation to the bollard - apart from being a bit low is it concrete filled? If not I would suggest filling it with concrete - that will reduce flexure.
As I say - don't want to dampen the spirits but would hate to see you go to great effort for an avergae result.
I'm starting out on what will no doubt be a long and expensive journey, but I'm hoping the end cost will be less that a dome purchase - which can start out at around $5k for something decent.
So, budget requirements led me to plan a skillion roof shed and have the roof "flip" on a simple hinged arrangement. I've obtained a bollard which will form the base of my pier and have to find someone that can machine and weld a steel plate on to that, then an aluminium plate separated by threaded rod for levelling.
I'm a little worried about flexure in the metal, but will just have to leave those worries alone for the time being and get the shed up in the first place, then bolt the pier in place on the slab - which is actually the top of my in-ground water tank.
Some pictures of how it looks now. In a few weeks I'll start to mark out the shed spot and get the family over for a good shed building and bonding experience
SImon, since you'll be bolting the pier to a slab you can use nuts above and below the pier base as a levelling mechanism instead of having a separate adjustment plate made for the top. Just be sure the bolts in the concrete are long enough. I use 1/2" threaded rod and it works fine. I have this arrangement on one of my piers - with appropriate mounting holes drilled/tapped into the top plate on the pier and a small window cut into the side of the pier just below the top plate so I can get a spanner inside to tighten down the centre bolt that your mount will certainly have. I can draw it up if that would help.
Peter
I'm hampered unfortunately by geography and err...I think I'll call it aesthetics for now (what can I say, other than my overriding instruction has been "If you get in the way of my nice view I will make you invent a cloaking device" ). My property has a gully running right through the middle of it, which is basically a moisture trap so I can't go further down the property or I'll end up being a participant in that Monty-Python sketch where they build the castle in the swamp, can't build off to the side or in front (driveway in front, large shed to one side, house to the other). The options are not good
You are right of course, the top of the tank is going to give some vibration. My only hope is to mount the pier in a way that dampens it all, which I have some flexible tile glue and a piece of marine rubber matt. I'll make a sandwich of that in between the tile adhesive and hope that does the trick (along with bolting it in to the slab which is only 200mm thick - you are correct there). The pier is concrete filled, which will reduce vibrations to some extent.
Peter I appreciate the offer of diagrams, I admit I am struggling with the best way to set this up - but cannot actually get in to the middle of the pier to fix a centre bolt.
appreciate your constraints, particularly the non-physical ones!
Will you have a raised floor? I think if you are able a floor that is not tied to the tank top would really help unless you are planning totally remote imaging? Maybe bearers that run from stumps either side of the tank and floor on that?
Yes! That's a good idea. I'll look at what I can gather that will do just that. This way I could put the remaining Insulshed in between the bearers and the floor, giving a good barrier for whatever moisture forms under the floor to condense on and 'drip' off again before it gets inside the shed.
My tinshed OBs, SkySlab has a floating floor. The 4 x 4 meter slab of concrete it sits on tends to puddle when it rains. The floor sits about 300 mm above on bearers and blocks with a plastic damp proof membrane beneath. Isolates from the pier which is secured to the slab and keeps it all dry above. No problems so far at all.
I just cut it so it was a tight slide fit then a bit of Duct tape. Fortunately water doesn't climb upwards very well, it obeys the law of gravity and stays down below. My Ob has lots of airgap holes at the wall base and roof line, corners etc so stays quite dry.
I normally get mine aligned and guiding from the dome, then kick off the image capture remotely from inside the house. No vibration problems when your not there
Coming together in bits and pieces. Two pictures, the shed being constructed - still have to put it together which is not actually as easy as the instructions all say. Ever tried to use self-tapping screws to drill into a flexible very thin sheet of zincalume? Sufficed to say that pilot holes make it all easier. The second picture is my home made pier in the middle of a coat of gloss black. This beauty has cost me about $100 so far.
I've had the tank 'tested' for vibration - sort of jumped up and down on it and used an accelerometer a friend had - no it wasn't my iPhone. Yes, it's a drum. It picks up vibration quite nicely and distributes it across the whole surface with surprising clarity! So, mounting the pier will require some flexible tile glue, a piece of thermally treated (exterior) rubber and some dynabolts. The glue and rubber will absorb vibration to some extent, the dynabolts hold it all in place and the pier is actually 165mm diameter, 6mm steel filled with concrete so the vibrations will be dampened significantly.
I've managed to land a 20mm piece of 256mm aluminium from a supplier in Sydney for about $35 (shipping was a bit more - but still cheaper than getting it from anywhere in Canberra!). I purchased a mini pier from ioptron for about $100 for the ieq45, again shipping was a bit more from America but it beats $500 for a plate designed from Dan's plates in America. I'm going to tap some threaded holes into the aluminium plate, mount to top part of the mini-pier (it comes off! Gives me a nice template and mounting block) directly to the aluminium plate and that way I can take it off and tap some new holes when I upgrade (or just get a new aluminium plate, not expensive).
So far, have got away with it for under $900. The wood for a floating floor will be a little expensive as I'm not going to get that second hand. I expect all up it might be about $1500 when finished.
You'll see in the picture I have some SW pipe and some black...err...other...pipe. I'm going to attach the SW pipe to the top of my inspection valve from the outflow of the water tank - water does not come up the inspection valve as it's higher than the overflow outlet. I've purchased 1kg of activated charcoal which I will hold inside the pipe with some stockings stretched over the air outlet. This will provide water cooled air into the shed. The air outlet will be a twin chimney system (yet to be fully designed by me) consisting of the black pipe, rising up from the top of one of the sides and capped (with a u-bend at the top and a mozzie-proof open air outlet). What I plan on doing is using the vacuum that the heated air in the chimney will create to draw cool air in from the air inlet (described above). It's only good for cooling down the shed when I'm not using it - as the roof will hinge off when I'm using it. But I hope that will make the whole thing a little more thermally sensible. I've got some insulshed that will line the whole thing. Best to jump in and experiment I say.
Some shots of the shed going up and how the pier is looking.
Shed took some pounding on the weekend with very strong winds. It wasn't easy putting this thing up in those winds - but once all four sides were in place it's very stable.
Looking good so far. My roof rotates sideway 90* to open. Much easier than having to balance a flipped over roof with rods or ropes etc. I just unclip the restraints, lift it gently with my hands and walk it around. Had to strengthen the upper wall top 'rail' to stop flxure but that was just some 6 x 1 (150 x 25) timber secured and braced in the corners.
The tank is actually quite flat, there are points where it dips and rises but in general no more than 2 or 3mm at any point. It was poured when the house was first built - so it has an 11m diameter on the top, goes down 3.5m and is currently about 3/4 full of water. We use a fair amount being a family of 4 (3 females and me) but the rainfall here is pretty good.
Any dips or rises were taken care of by putting some aluminium angle down first, then attaching the shed sides to the up-right part of the angle. This had the effect of levelling out any bumps without needing to pour concrete.
Silicone helped a bit too...
Here's a shot of the aluminium going down first, you can see the upright part of the angle? That's what the shed was riveted on to. I added more angle the create a box frame first, then put the shed on to that frame.
Passive cooling using a solar extractor fan on the top of a tall chimney, air intake off the overflow from the water tank: Water cooled air coming in, hot air being taken out.
The effect is variable depending upon conditions, the hotter it gets outside the more effective it is but on average I get a 2 degree temp below ambient temperature.
Insulation and wall coverings help.
It's ready for a lick of paint and some very thin ply on the roof and doors.
Looking good !
Fortunately we don't get the big temp swings you guys seem to get and my tinshed is in a protected enclosure out of the worst of the sun so no requirement for insul or vents. Leaks enough air to stay about ambient and not need serious venting.
Won't the chimney get in the way of viewing somewhat or are you blocked on that horizon anyway ?
Yes it will a little bit - but that's ok, the mount will be high enough that it will 'see' over the sides of the shed, the chimney however is going to block some sky if I want to look that way.
It's something I'll need to put up with...
However you are right, the temperature gets high for a small amount of time during the year, but I wanted to make sure that my equipment suffers as little stress as possible during those times.
). My property has a gully running right through the middle of it, which is basically a moisture trap so I can't go further down the property or I'll end up being a participant in that Monty-Python sketch where they build the castle in the swamp, can't build off to the side or in front (driveway in front, large shed to one side, house to the other). The options are not good 
