Garden Observatory

[Ian]

sounds more like he had a particular problem with his observatory rather than domes or metal sheds in general. Wooden sheds are usually poorly sealed. Not a fault, just a way they are, but metal sheds can be tightly sealed. It may also be that this particular observatory has a poor or non-existent moisture barrier in the floor.

Condensation can be reduced by ventilation and stopping the moisture getting in in the first place. Sounds like a contradiction, but it's not really. Seal the top and the bottom, stop rain and ground water getting in, but ventilate the sides to get a decent air flow through the building. Dehumidifiers are not really a permanent solution. I don't think I'd want to bake any of my kit in an oven either, wouldn't want any of the optical cement in any of it melting.

[Fay]

http://www.newforestobservatory.com/index.php/observatory

Our garden shed is very dry, it has ventilation at both ends. I have heard it a few times, regarding fibreglass & metal buildings. You are right it is not the answer to run a de humidifier all the time.

[Tony G]

Fay,
The gentleman you spoke about with the moisture problem (was he an old man?????? ) made a few mistakes. First he should not build an observatory in a stream, Second he shouldn,t leave the heater on constantly, it should be regulated and third it would help if there was some form of insulation or vapour barrier on the inside lining of the shed/observatory.
A de-humidifier would be no good in an external housing, because it would absorb the moisture within the shed (condensation) as well as absorbing the moisture externally (due to any gaps and joints), and with this countries climate, I would say you would be emptying it more frequently than every two days.
You could always fix foiled backed plasterboard internally with a gap between the board and the outside skin of the shed plus a couple of vents to stop any stale air inside, like airbricks under your ground floor flooring, and then fix some tube heating as in the link you started this thread with, and I know where you can get some of these, nudge, nudge, wink, wink, say no more. .
Well that my opinion anyway.

Hope this helps.

Tony G

[Tony G]

Sorry Ian,

I didn't realise you and Fay had posted until I hit the post button

But roughly along the lines as what I posted

Tony G

[Ian]

at least we didn't completely contradict each other

Thanks for the link Fay, he's got no moisture barrier underneath, unless he missed it out of the description of the works. Just a wooden deck over the ground. Most of the moisture would be coming up from beneath I suspect. There's the possibility that heating the dome could make it worse too, vaporising more of the ground water...

[Fay]

Oh, it is interesting to hear your's & Tony's opinions. Should he have a thick sheet of plastic incorporated in the cement floor?

[Tony G]

Fay,

A sheet of polythene would definitely stop any moisture, but make sure that there is a layer of soft sand laid down prior to the polythene, as people put the sheeting directly onto the hardcore and when they concrete do not realise that the hardcore can rip the sheeting with the weight of concrete and produce a nice hole for the ground water to penetrate.
Fay, if you do go ahead with this, there are plenty of us here to help, me with advice, and the rest with their muscle and willingness.

Good luck,

Tony G

[Fay]

You are so kind, as usual.

[Fay]

A couple of very interesting links. The chap at Crayford, that I put the address on earlier had this link on his site. It is where he got his idea from

http://www.linnhe2.free-online.co.uk/observatory/index.html

[Fay]

Well, that was such an interesting read! The Linnhe Observatory.

All the work & technical knowhow that you need, scared the wits out of me. Jealous of his view!!

[JohnP]

Jealous of his view!!

yes but not the winds or salt water..... imagine the potential for corrosion...

[RobertM]

Hi Fay,

Here are some of the better sites that I've found while researching...

http://www.jwrking.com/my_observatory.htm
http://www.richweb.f9.co.uk/astro/construction.htm]
http://www.aozc64.dsl.pipex.com/tips/observatory.htm
http://stoney-hills.com/html/observatory.html
http://arnholm.org/astro/observatory/index.htm
http://www.dosborne-astroimages.co.uk/equip.htm#observatory

The last is the most interesting design from my point of view.

I hope you find them useful.

[Fay]

Never thought about that bit John. There is always a trade off.

I will look at those sites Robert. Have you done anything yet?

[Fay]

Robert I really like that last one.

I think it is funny that always the wife or husband is mentioned!!!!

[RobertM]

There is nothing to show other than a few wood shavings where the tree was.  Everything else is either in my head or mad ramplings on scraps of paper.

No doubt your husband thinks that it should be invisible like my wife - my wifes comments range from 'how much !' and 'does it need to be that size' to 'wouldn't under that tree in the corner be better' !  Wonder how she'll react when I ask her to help with the concrete .... I'm thinking the worst at the moment