Planning an observatory - questions...

Hi guys. Long time lurker, first time poster here.
I believe there are a few members who have been through this - hoping to tap in on a little experience here.
So, I'm in the planning stages of building an observatory and I've settled on a roll off roof type with timber frame and shiplap exterior. I'm unsure whether these require planning permission though. Is there some threshold in dimensions beyond which planning permission applies, or is it not quite as simple as that?

There are at least a couple of us with designs like that so ask away!

I went with the reasoning that the observatory was basically a garden shed.

The planning requirements (for me in Dun Laoghaire anyway) for a shed (though it's very similar to what's required for an extension) are:

* It is not forward of the front wall of the house;
* Not greater than 25sqm (or no. of sheds aggregated);
* 25sqm of garden space is left. N.B. extensions attached to house are not reckoned as private open space;
* Shed finish is in keeping with the house;
* Shed height: max 4m pitched roof; 3m flat roof;
* It is not lived in or used for keeping of animals (pigs, ponies, horses, pigeons).

The 'shed finish' seems to only apply if the shed is at the front or side.

So you should have no problem from a planning perspective putting up a reasonably sized observatory provided that you don't have a really tiny garden.

Planning permission rules, I think, will depend on the council and will likely differ in detail from one council to another.

However, an observatory based on a shed will unlikely require specific planning permission as it is not a permanent structure and will not consume a significant percentage of garden space.
There may well be height restrictions (and 4m rings a bell with me - and that's generous) - but it is unlikely that your plans will exceed this.

If - when not in operation - it is pretty much indistinguishable from a normal shed then I really doubt if you will have a problem.

I have a 2.2m (diameter and something of that order in height) dome (physically in situ for about 1 yr - but not yet in operation) and while there is some local curiosity I have no complaints (I'm in Fingal Co Council area).

Have a look at your local council's website - or if you know - or want to know a councillor - ask them.

Unless you do something that your average neighbour will regard as outrageous I suggest that you will be fine. There is considerable tolerance (but of course there are limits) to what we do in our back gardens.

There are several on this forum who can give advice.

Best of luck with the venture.

Mark C

Thanks a lot guys, that's really put my mind to rest on the issue.
I've found a build blog of a great design that I think I'm going to go with, roll off with the roof rolling onto warm room roof. Approx 2.4x4.8m.

Just wondering now if there's any points that cropped up towards the end of your builds that you wish had been thought of before getting underway. I'm conscious of parked-scope-height/pier height and wall height, but I'm sure there'll end up being something that I'll wish I'd thought of at the outset.

which design did you find Mike. I went to see one over the North side of Dublin last year. Dont think the lad who owns it is on here, but if you PM me ill send you the link to his website.

Its a shed with half the roof rolling off, so you dont need supports for the roof when its out.

Will probably go with something very similar to the build in this thread . Although I think the main door should be into the warm room rather than scope room. He did a very thorough job though.

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