Astrokev's Obsy Build

[Gina]

Oh yes indeed, it has to be a compromise. My view north and west is limited by buildings and trees so I made my north wall about 6" above floor level. That worked out quite well. The highest trees and buildings were to the NW so I arranged the ROR and warm room in a westerly direction. This means I lose out on some sky to the west. However, we have neighbours in that direction with a 500W flood light so it has it's virtues

[fwm891]

Kev - What about having your low walls for sky access and the higher roof...

You can keep your WR at full height and run the side wall/roof over it

[Gina]

Yes, mine's like that but with unequal sides/walls. 6ft to the north and 4ft to the south with a fold down flap on the end/east wall.

[Digz]

A stepped floor is an ideal but will add complexity to the build, not mention complexity of getting kit in without tripping!

Working out your wall heights, in theory, shouldn't be too difficult. Some trigonometry and a nice scaled drawing should help.

[malc-c]

One thing to think about is that if the building is within 2m of a boundary line you may be confined to the maximum height restriction as set out in the planning regulations regarding outbuildings. There is a lot of grey areas here, as it's not clear from which point you take as being ground level if the building is on a slope (as is my observatory). The max height is 2.5m high under current regulations in such cases, which if this is taken at the absolute value, and your ground slopes steeply, would make for a very low ceiling in the warm room. I'm not sure if they average it out, so if it's 2.6 at one end and 2.2m at the other, then the average would be 2.4m which would be under the max, or if it means any point of the structure must not exceed 2.5m (mine is bang on.... )

There are other planning permission regulations depending on the area of the garden the building is going to take up, which is more of an issue if your garden is small and you want an observatory with almost 12 sq meter floor area.

[Digz]

A very good point Malc. Also remember these permitted development right can also be revoked if you live in a designated area such as a SSSI or AONB. If in doubt speak to a local planner to confirm.

[Astrokev]

One thing to think about is that if the building is within 2m of a boundary line you may be confined to the maximum height restriction as set out in the planning regulations regarding outbuildings. There is a lot of grey areas here, as it's not clear from which point you take as being ground level if the building is on a slope (as is my observatory). The max height is 2.5m high under current regulations in such cases, which if this is taken at the absolute value, and your ground slopes steeply, would make for a very low ceiling in the warm room. I'm not sure if they average it out, so if it's 2.6 at one end and 2.2m at the other, then the average would be 2.4m which would be under the max, or if it means any point of the structure must not exceed 2.5m (mine is bang on.... )

There are other planning permission regulations depending on the area of the garden the building is going to take up, which is more of an issue if your garden is small and you want an observatory with almost 12 sq meter floor area.

Hi Malcolm.

Thanks. Fortunately, my garden is pretty flat so will make establishing a datum point fairly straight forward. We also have a fair sized plot so footprint should not be an issue. The building will be close to our boundary fence so I need to be careful though

[Astrokev]

A stepped floor is an ideal but will add complexity to the build, not mention complexity of getting kit in without tripping!

Working out your wall heights, in theory, shouldn't be too difficult. Some trigonometry and a nice scaled drawing should help.

Hi Digz,

Doing the calcs and trig is easy. Deciding what I want is the difficult bit . My sketchup designs have all the angles shown for different tube positions. The challenge is deciding where I want the compromises! The stepped floor idea will, as you say add a lilttle complexity, but not too much if I use block walling and hang the joists off these. That said, I can't decide if this is what I want to do. Oh decisions, decisions....

As some have said, maybe I just need to decide a wall height and go for it, without being too fussy about low viewing angles. After all, most of my observing will be at higher altitudes.

[Astrokev]

Kev - What about having your low walls for sky access and the higher roof...

You can keep your WR at full height and run the side wall/roof over it

Thanks Francis. Certainly something worth considering!

[Digz]

Hi Digz,

Doing the calcs and trig is easy. Deciding what I want is the difficult bit . My sketchup designs have all the angles shown for different tube positions. The challenge is deciding where I want the compromises! The stepped floor idea will, as you say add a lilttle complexity, but not too much if I use block walling and hang the joists off these. That said, I can't decide if this is what I want to do. Oh decisions, decisions....

As some have said, maybe I just need to decide a wall height and go for it, without being too fussy about low viewing angles. After all, most of my observing will be at higher altitudes.

I know what you mean, the hardest part of any design is deciding which option to pursue.

[Gina]

I wouldn't recommend a stepped floor - accident just waiting to happen. You need to keep tripping hazzards to a minimum.

[Astrokev]

Yes, mine's like that but with unequal sides/walls. 6ft to the north and 4ft to the south with a fold down flap on the end/east wall.

Sorry Gina, missed your post there. Yes, your design worked well. I'm going to give this approach some further thought and may well pinch a few ideas from you (if I can find enough time to plough through your humoungous thread(s) to find the relevant bits! :grin:

[Gina]

Sorry Gina, missed your post there. Yes, your design worked well. I'm going to give this approach some further thought and may well pinch a few ideas from you (if I can find enough time to plough through your humoungous thread(s) to find the relevant bits! :grin:

The "Abbreviated" ones are a bit more manageable Im afraid I do tend to have "more rabbit than Sainsbury's"

[Astrokev]

The "Abbreviated" ones are a bit more manageable Im afraid I do tend to have "more rabbit than Sainsbury's"

Hi Gina,

Absolutely right. Just had another run through your abbreviated main construction thread. A very nice summary and really helpful to have all the images so close together. I'm very tempted to follow your side-to-side arrangement of your apex roof, which makes designing the join with the warm room roof a little easier, as I think you mentioned in Chris's thread .

[Astrokev]

Hi Gina,

Absolutely right. Just had another run through your abbreviated main construction thread. A very nice summary and really helpful to have all the images so close together. I'm very tempted to follow your side-to-side arrangement of your apex roof, which makes designing the join with the warm room roof a little easier, as I think you mentioned in Chris's thread .

As an afterthought, what slope did you end up using for both the warm room roof and the main apex? I remember reading this in your original thread, but it may be difficult to find this.

Thanks

Kevin

[Gina]

As an afterthought, what slope did you end up using for both the warm room roof and the main apex? I remember reading this in your original thread, but it may be difficult to find this.

Thanks

Kevin

Good question As I recall, the warm room was about 2 degrees. About 2" in 6'. The apex ROR was something like 8" in each 4' side I think. I'll see if I can remember to check tomorrow, in daylight.

[r3i]

As an afterthought, what slope did you end up using for both the warm room roof and the main apex? I remember reading this in your original thread, but it may be difficult to find this.

Thanks

Kevin

I asked a similar question during my build and got this useful info: http://stargazerslounge.com/topic/168972-yet-another-observatory-build-thread/page__st__20#entry1726558

My warm room has roughly a 1 in 25 slope - it gets rid of the rain OK.

[Astrokev]

Good question As I recall, the warm room was about 2 degrees. About 2" in 6'. The apex ROR was something like 8" in each 4' side I think. I'll see if I can remember to check tomorrow, in daylight.

Thanks Gina,

Sounds like I can get away with a very shallow gradient, which opens up the design possibilities nicely.

Kevin

[Astrokev]

I asked a similar question during my build and got this useful info: http://stargazerslou...20#entry1726558

My warm room has roughly a 1 in 25 slope - it gets rid of the rain OK.

Thanks Mike,

Very reassuring!

Kevin

[Astrokev]

My design is progressing slowly, and I'm now focussing on the rolling roof.

Can I ask what wheels folks can recommend?

Thanks

[r3i]

Can I ask what wheels folks can recommend?

I'd go for circular ones.

I went for 100mm rubber wheeled ones from Screwfix, early days yet but are working OK. However there has been comments in other threads that rubber ones might end up getting flat spots after a period of time and they suggest the full nylon ones might be better.

Another option are the ones with a V-groove that run on something like a length of inverted angle-iron. Probably more expensive than the standard Screwfix offerings but I would imagine they'd offer less friction. I think a source for these might be electric gate suppliers.

[yesyes]

I would also recommend round ones...

I haven decided on wheels/castors for my obsy yet, so will be watching the recommendations here.

I kind of like the idea of these V-grooved ones as that would provide the sideways support as well. Also, water wouldn't collect on/in the track. The question I have is how do you attach the angle track without the screws getting in the way of the wheels?

[r3i]

The question I have is how do you attach the angle track without the screws getting in the way of the wheels?

The ones suppled for motorised gates have a wide profile that keeps the fixing locations well away from the wheels - some examples here: http://www.barrier-components.co.uk/sliding-gate-hardware/sliding-gate-rails.html

For those that have use inverted angle iron, I think they used countersunk holes and the fixings are screwed into the top of the wall at 45 degree angles.

[r3i]

Another method is to weld the angle onto a length of flat plate and screw the plate down : http://www.skyimager.com/images/Observatory-0026.jpg

[Astrokev]

I would also recommend round ones...

Thanks guys. Very helpful

Yeh, V grooved wheels look great. Something to look into there. The reason for wanting to make some decisions on the wheels this early on in the project is so I can finalise my design for the roof itself - how much space to leave between the top of the walls and the main roof support beams. This will affect how I design the seal between warm room and scope room, and the sides of the roof to minimise the gap between roof and walls. (hope that makes some kind of sense).

I'm designing in Sketchup, so must post a few images to brighten up the thread before the build starts proper.

Kev