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Roof hatch

paulwhiskey2

By paulwhiskey2
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paulwhiskey2

paulwhiskey2

Posted
Posted

Hi Everybody

This is my first post, but I have enjoyed reading the forums for a while.

I am looking into putting a hatch into my loft roof for observing and I thought I would seek advice from the forum members regarding their experiences and references to previous threads and publications.

I have thought about a loft roof hatch , or even two, for the following reasons:

1. View restricted at ground level by trees

2. Cheaper and simpler to fit than a dome and does not require planning permission like a dome

3. Telescope can be left set up

My house has pitched roofing at two right angles, so hatches can be fitted facing north, south, east or west.

I have a 250mm Dobsonian and 90mm GoTo, so hatch would probably need to be at least 4 feet across to use the big scope.

I am also trying to think of some sort of drape that would help to provide some sort of draught exclusion around the scope.

Here goes for a project !

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ToxoLight

ToxoLight

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Posted

Hi Paul and welcome to the lounge, my first thought is that heat rising from the house might make for turbulent seeing but other more experienced gazers will be along soon to offer advice.

Clear skies T.L

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fatwoul

fatwoul

Posted
Posted

Hi Paul

I can't give any information about roof hatches, but if planning permission is the only obstacle preventing a dome (or roll-off roof observatory) then you should probably double-check. My dome was built without planning permission, and my understanding is that provided it isn't higher than 3m (or 2.5m if near to a neighbouring fence, etc) it doesn't require permission. There are some other limitations: for example, you can't fill more than a certain percentage of the land around your house with additional buildings, etc.

My SkyShed POD comes in well under the 2.5m limit, and is dismantleable, so if pressed I'd argue it was a temporary structure anyway.

Roll-off roof observatories are basically just sheds, and you don't normally need planning permission to build a sensible-sized garden shed...do you?

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fatwoul

fatwoul

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Posted
Hi Paul and welcome to the lounge, my first thought is that heat rising from the house might make for turbulent seeing but other more experienced gazers will be along soon to offer advice.

Clear skies T.L

Also, if Paul plans to do any deep sky imaging, he'd be at a disadvantage in being unable to isolate the telescope from the surroundings, since he couldn't use a pier and concrete base.

Having said that, it's been done, and if I can remember the thread, I'll post a link to it!

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JamesM

JamesM

Posted
Posted

Hi Paul and welcome to the forum. I understand your frustration and at first glance your suggestion would seem to be the perfect solution. However, as already mentioned by Toxolight above, thermals are going to be your problem I'm afraid. There will be the heat escaping from inside the house through the hatches along with the rising thermals from the roof tiles that have been subject to the sun's rays all through the day. Try observing objects over the neighbours rooftop to see the effects of warm thermals have on your view. It's bad enough waiting for the scope to cool down in order to get some decent resolution of the mirrors. I have seen some pictures of american amateur astronomers who have constructed a dome on top of their house but the lengths they have had to go to in order to insulate the structure from the rest of the house, (helped of course by having a huge house to start with in order to facilitate a remote viewing position) is clearly something that can only be achieved with a serious amount of money.

There have been several posts on here in the past, where people have had to deal with neighbour's complaints regarding 'men using telescopes' in the middle of the night and that was in their garden! I wouldn'i like to guess how popular you would be sticking your 10" telescope out through your roof - probably get a visit from a police helicopter!:D:D: Managing the thermals will be the key if your plan is to work.

Clear skies for now

James

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LukeSuppalot

LukeSuppalot

Posted
Posted

Hi Paul and welcome to SGL.

Firstly, roof lights or hatches do require planning permission if they are on the front elevation of the house or if they overlook a neighbours house.

Secondly, a 4 foot wide opening would require a fair amount of work and money to remove at least 3 rafters and doubling the rafters either side for strength. Also the hatch/velux has to be made watertight.

Lastly, chances are that the joists you will be standing on will be no more than 4"x2" ceiling joists so will deflect by at least 1" when you walk on them. You need at least 8"x2" at 16" apart covered with 22mm t+g chipboard to get a somewhat stable floor.

I reckon it would be far easier and cheaper to pay a tree surgeon to lop 6-8 feet off the trees.

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glowjet

glowjet

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Posted

Hi Paul and welcome to SGL, very sound advice already given, I know it my be a bit of a downer, but I fear you would waste your money. Even if you chose not to follow the advice and went ahead, I think you would be disappointed with the end result. Lets face it, if it was a successful way to achieve good viewing, there would be many thousands of Astronomers who would have installed roof hatches and there would be a wealth of information available. It might be cheaper and better for you in the long run if it is at all possible trim you trees :D

John.

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SteveA

SteveA

Posted
Posted

Hi Paul,

The comments posted here regarding the issues with heat rising are valid, along with the planning permision issues as well...Like Fatwoul, I've a POD and didn't obtain planning permision as it can be considered a temporary structure.

You may be interested in an article that appeared recently in Astronomy Now...I think it was last month (Feb 2012). This dealt with exactly this topic, ie observing from inside your property....

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ollypenrice

ollypenrice

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Posted

I too think rising heat would make this unworkable. There is also the issue of working from a suspended timber floor. People who try observing from garden decks usually report huge levels of vibration, which is not surprizing. This might be a huge lot of work for not much sccuess.

Olly

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swamp thing

swamp thing

Posted
Posted

Hi

Welcome to the forum.

Another thought is the 4' roof hatches are normaly centre or top hung so useless for pointing anything like a 10" scope out of.

I tried exactly this with a 4.5" scope through a 4' Velux roof light years ago, waste of time.:headbang:

You'd be better off spending the money you would have spent setting this up on a small van to transport you and your Dob to some quiet dark spots way out of town.:D

Regards Steve

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