Obs - Planning stage

[astroimpulse]

Hey all

So I'm at the planning stage of my Obs and once this season's garden building jobs are sorted I'll begin with the hope of being ready for the winter.

I'll start with the pier so if worst comes to worse I'll have that in place.

My issues have only been around the roll off roof and I've been investigating different ways and I've settled on a full roll-off...at the moment

I have to have it look nice in situ so it'll be a pitched roof design and have clean lines. Pretty much ruling out roll-over which would be the most practical.

I've knocked up some images to illustrate where I've arrived at at the moment and would be interested in some discussion from you experienced users

Due to the way my garden is, I only have a certain place I can have the Obs and the below images have it in that position.

The footprint is 4m (13') x 2.5m (8'). Careful planning will be made to ensure the correct pier and wall height. Currently at 2m (6.5').

1: Roll off the roof the traditional way. The issue here is I can't go West and I can't have the supports slap bang in the middle of the decking which will be built there on the right of the image. So it would have to extend right over and this means crazy long supports as the other side of the railing is a high drop. So it's a no-goer.

2: Roll off perpendicular to the obs. Not traditional but the only way. It will have to roll off to the rear for a few reasons. A: It can't take up more of the lawn which I've worked hard to create the area for. B: It will not cause any blocking of available sky as it's a little woods behind so it doesn't block anything.

But the split roof rolling off perpendicular means the joint will be prone to leaks. There's work-arounds and solutions to this but I believe in keeping it simple. I'd prefer this option but the join rules it out.

3a: This is the one I think is a goer. The whole roof will roll off perpendicular, again, and the warm room will have a secondary roof skin. This will mean it's still covered but as the roof is the waterproofing element it doesn't need to be sloped etc.

It's quite a size to roll off, though, so this will be the compromise on this one. I'm a strong lad but if it proved hard I could always introduce a mechanism to help

3b: This shows the rear. As you can see there is quite a rise on the rear 3.2m (10.5'). Also the West side runner can't be planted as it will be in the way of the stairs. So it will be supported by diagonals and also the roof will have a 4th runner which will support more of the weight once off the Obs. Internally that runner will only have end supports so not to be an obstruction.

All in all I think this will suit my needs and offer me the most sky from my location.

Can't wait to start!

Would love to hear some thoughts And sorry for the long post

[RogerTheDodger]

#2 makes the best sense, all the others are moving more mass over the warm room for no reason.

[astroimpulse]

Yep, totally. That's what I said above (my favoured) but explained the reasons why I'm not going to end up doing it.

There is a reason for moving the whole roof on this occasion.

I forgot to mention the wind issues also in that part of the garden which makes a complete seal all the more important.

I tried my best to make the first post short and clear . It's a novel! hehe

[swamp thing]

Hi

I would go for #3 keep it simple to make water tight. Perpendicular joints in pitched roofs are not a good idea IMO.

Regards Steve

[astroimpulse]

Yeh, it's where I've arrived for the same reasons. The work-arounds are just adding possible future issues too.

Thanks for all the thoughts so far guys

[Bizibilder]

In 1. I'm not sure why you need the "full length" roof? If you only had a moving roof that was the size of the observatory (as in 2.) and a flat warm room roof (with a very small downslope) you would not need any supports as the roof would open over the warm room. The runners could extend with diagonal braces up from the warm room end wall but you may find this unnecessary (depends on dimensions). ie as in 2. but the roof moving East over the warm room.

Hope this makes sense!

[astroimpulse]

No, it makes sense And it was my initial plan.

But as I tried to explain...it has to be ascetically pleasing in situ too.

The full pitched roof will look attractive and it's one of the stipulations of being allowed to build a great big shed in our garden.

[Gina]

In 1. I'm not sure why you need the "full length" roof? If you only had a moving roof that was the size of the observatory (as in 2.) and a flat warm room roof (with a very small downslope) you would not need any supports as the roof would open over the warm room. The runners could extend with diagonal braces up from the warm room end wall but you may find this unnecessary (depends on dimensions). ie as in 2. but the roof moving East over the warm room.

Hope this makes sense!

I agree with that. As long as the warm room is more than half the obsy, the roof would not need any support outside the warm room. This is then a conventional roll off roof design.

[astroimpulse]

I have to have it look nice in situ so it'll be a pitched roof design and have clean lines. Pretty much ruling out roll-over which would be the most practical.

I knew the post was too long...lots lost in the epic novel!

It's a no goer unfortunately.

[Bizibilder]

In that case 3. is better than 2. mainly due to the elimination of a very hard to seal join - as you say in your original post.

[Gina]

The full pitched roof will look attractive and it's one of the stipulations of being allowed to build a great big shed in our garden.

I see what you mean. Unfortunately, sliding the whole roof off does mean extra supports and a peculiar wooden structure attached to the shed. Personally, I think a double pent roof where the obsy roof slides over the warm room roof, looks better. OK so it looks like two pent roof sheds attached to each other with one a bit higher than the other. But it takes up no more room than the obsy and warm room. It's also very much easier to make and engineer.

It might be possible to have the two roofs level and arrange that the obsy roof lifts then rolls off. More difficult engineering but aesthetically nicer looking. It would need thinking about.

[astroimpulse]

In that case 3. is better than 2. mainly due to the elimination of a very hard to seal join - as you say in your original post.

Yeh. I came up with some crazy ideas on how to seal the joint and just though "what the hell am I doing! Just keep it simple"

Needing it to look clean and smart is the main reason it's needed more thought than usual. I'd prefer the roll over anyday. But I do agree with the other half on it looking nice too as we're spending a lot of time, effort and money on making the garden nice.

What's are people's thoughts on 2.5m² (8' x 8') for the main area? It's well enough for my set-up but not sure on future expansion (like a big newt etc). Do you guys have bigger?

[Gina]

What's are people's thoughts on 2.5m² (8' x 8') for the main area? It's well enough for my set-up but not sure on future expansion (like a big newt etc). Do you guys have bigger?

My obsy will be 2.4m square based on the standard lengths of timber. Have you got to that stage of working out how it will be made yet? I need to keep cost to a minimum and using plywood for the walls. These are 8ftx4ft - 2440x1220mm and studding and other timber comes in 2.4m as the nearest to that. I thought of 6ft or 2m square at first but decided that was too small. I think 2.4m square should be the ideal size.

[Bizibilder]

This may be a daft idea but have you considered some form of "dome" - gets round the space problem, looks the business and is not that difficult to make (says someone who has never made one!!)

[astroimpulse]

I see what you mean. Unfortunately, sliding the whole roof off does mean extra supports and a peculiar wooden structure attached to the shed. Personally, I think a double pent roof where the obsy roof slides over the warm room roof, looks better. OK so it looks like two pent roof sheds attached to each other with one a bit higher than the other. But it takes up no more room than the obsy and warm room. It's also very much easier to make and engineer.

Thanks Gina

I agree on supports adding to more engineering and look potentially more unsightly. But because they run-off the back and form a tunnel type arrangement, over the area in the pic, they will give us a nice area before the stairs. Eventually this will have hanging flowers/plants etc so will look quite smart and add to the garden rather than take away. If that makes sense. Eventually the stairs going down to the little wood will be an area we use more.

It might be possible to have the two roofs level and arrange that the obsy roof lifts then rolls off. More difficult engineering but aesthetically nicer looking. It would need thinking about.

Yeh, I played around with this idea for ages. I saw a huge obs in another thread (was a link to a USA guy) and I played around with it on a smaller level because I was a big fan. But because of the proportions it actually looked ugly It looked like two skinny miniature buildings side by side. Engineering it was fairly straight forward though.

My obsy will be 2.4m square based on the standard lengths of timber. Have you got to that stage of working out how it will be made yet? I need to keep cost to a minimum and using plywood for the walls. These are 8ftx4ft - 2440x1220mm and studding and other timber comes in 2.4m as the nearest to that. I thought of 6ft or 2m square at first but decided that was too small. I think 2.4m square should be the ideal size.

Oh yeh. It's going to be a wooden frame (on a block footing), ply and shiplap. The roof will be also shingled.

I've have a fair bit of 3.6m timber already but some of the big posts can only be bought at longer than standard sizes from timber merchants. As you know...non-standard = higher prices It's not going to be a problem though.

Paying for it in time for the dark nights is my biggest issue lol

Good to hear you have a similar size planned too. I set the size up around my gear and it does seem more than fine. I was thinking if I ever got a big newt or something it will change but I guess their not too much longer.

[astroimpulse]

This may be a daft idea but have you considered some form of "dome" - gets round the space problem, looks the business and is not that difficult to make (says someone who has never made one!!)

Yep...but dome=advertising you have astro kit. People will notice it more than just a shed (only obviously an Obs at night). I'd rather not have the attention.

Now, if I had huge private land...a dome it would sooooo be They do look super cool.

[nightfisher]

Yep...but dome=advertising you have astro kit. People will notice it more than just a shed (only obviously an Obs at night). I'd rather not have the attention.

Now, if I had huge private land...a dome it would sooooo be They do look super cool.

i agree, they look real cool but its broadcasting whats in side, im just starting to make VERY early plans for an obs, but it wont happen for at least 18 months as i have to get a divorce, then me and my girlfriend plan on selling our house`s and buy one together, i have already warned her new house will need a good aspect for an obs

[astroimpulse]

Best of luck with it all.

It's a good position to be; buying when you know you're going to be observing the heavens.

The vendors may find it strange when your request your viewing late at night, though hehe

[nightfisher]

Best of luck with it all.

It's a good position to be; buying when you know you're going to be observing the heavens.

The vendors may find it strange when your request your viewing late at night, though hehe

Thanks and yes its a good way to get of to a good start, though my obs will be very small, im thinking 2mtr x 2 mtr, with a pier and 150mm f8 frac, sorry for hijacking your thread

[astroimpulse]

It's not hijacking...it's contributing

It's all good

[malc-c]

Some thoughts,

Watch your construction. I found out that if you build your observatory from timber frame work in the same way as most sheds and other out buildings, and use a traditional felt roof it doesn't have to comply with the 2.5m max height planning regulation. If you place a tiled roof of any description it then has to comply with this regulation. Also there tends to be two traditional base construction methods, the solid slab and a dwarf wall with suspended joists. Both have restrictions if you wish to be exempt from the regulations. In a nutshell if it has to be demonstrated that the building is not a permanent construction and can be dismantled rather than demolished, and with little effort the area it occupies could be re-instated back to its former condition. It's a bit open to question as with the right tools even a solid 12" thick slab can be broken up and removed... If in doubt a check with your local planning authority should be part of your planning process.

One other suggestion for the planning stage is to spend as much time as you can phoning or visiting builders yards and comparing prices. Ask what offers they have and don't be shy to ask for cash deals.

Other considerations:

* Disposal of spoil. Even the smallest footings or base will result in a lot of spoil that needs removing. The cost of a skip can be as much as £250 so you need to build this into your costings. If what you dig up is good quality top soil then consider bagging it up and selling it for the cost of the bags - that way you get rid of it for free

* Materials to site. Most deliveries of bulk bags etc will have a max reach of around 20 feet from the kerb side, and you will need to move these to the area where you are building the observatory (normally the back garden). If like me you have a 17 year old son then employ him and a mate to do the laboring to move the materials for you. If you don't have this resource in your family then ask at a local youth club or 6th form and negotiate a rate. Again build this into your costings. For me my Son needed his moped repaired and he worked in exchange for me paying for these repairs. His friend received £80 for a days work barrowing three bulk bags of ballast / sand and 350 bricks 20yrds to the back garden.

* Tools. For less than £20 for a weekend it's worth hiring a cement mixer. Don't try it by hand as you will end up in traction ! also either hire or build in the cost of purchasing a sliding mitre saw (typically £100) to cut timbers nice and square. If possible obtain a decent cordless drill and or screwdriver which will make life easier.

* Weather proofing - if you can't store materials in side then purchase a tarp and cover the materials just in case that after all these days of dry weather it starts raining the weekend you plan to take delivery of several hundred lengths of timber !

* documentation - buy a decent ring bound note book and write everything down. Book mark anything you find in a dedicated folder and if possible print off the contact details and paste then in the notebook. Project management is often overlooked, but planning it out in a time line helps.

[astroimpulse]

Hi Malc,

Some excellent points there. Preaching to the converted (with me) but I reckon your post would do well to be stickied for those who haven't attempted anything in their past. In fact...with some additions it's not a bad idea.

Here's a cool site for those reading this page that covers many questions. If in doubt you can ring your local regs officer...they're actually great to talk to: Planning Portal - Interactive guidance for householders

They have a terraced one too and it's handy for quick queries. Each section also links off to more detail.

I've been building for a few years in the garden so the construction part is all in hand. I actually own a cement mixer too And you are so right about it being a god send. The amount of concrete I've mixed for footings and foundations in just my garden would be impossible by hand. I shudder to think. I paid £90 for it brand new from someone who won it but didn't need it. Score for him and me

I'm in my comfort zone with all of this building stuff. I have had many many tons of stuff delivered (checking it looks like 90+ tons so far ) and I have my preferred supplier too. I also have a lot of the materials already. Still plenty to buy but I reckon I've got about £400 worth of usable items in the garage atm.

The area you see is actually raised up 1m and the rest of the garden has an area that needs some stuff dumped in it anyways. I wish I'd know I was going to build an obs there as I wouldn't have backfilled at the time. It makes it a little less simple as the ground has not fully settled. Not an issue though. Just means a little deeper.

It's under 15m² (it's 10m²) too so exempt from regs but it complies with basic planning. The only thing is the 1m from boundary. But nobody adheres to that one.

The rules for height are actually 2.5 in height and 4m in total with a pitched roof.

Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.

4m would look hideous though (on my footing size)! lol Can you imagine...it would be like a church steeple!

There's one thing you've missed out from your experiences...having a son to help with the labouring Now that's priceless *nods*

My 2 year old little girl doesn't appreciate being asked to drag bags of cement

[Gina]

Very good advice Another small point... Sometimes you can adjust your dimensions slightly to make better use of materials and even reduce cutting.

I agree about a powered sliding mitre saw. I bought one some time ago when we were doing domestic alterations. It's been invaluable. It has had a lot of use and is so much less effort, quicker and, of course, more accurate than hand sawing. It easily cuts plastic (PVCU) cladding etc. - like going through butter. You need protective wear though as although it has a dust collection system, some still gets out, sharp bits can fly off too (despite the guard) so goggles are needed. The noise exceeds 90dBA so ear defenders are advisable too. Other power tools are a great help too. But they all need careful handling.

Edit... I see you're experienced so this is for general consumption.

[astroimpulse]

Here's a proper power tool!

I wish I'd actually owned it though Most of my garden was by hand and I could have done with it for longer. Only a small area was machine dug and that deep is solid clay and rock.

Still...if I did own it there's a possibility I would have dug and dug and dug. Great fun but maybe a home wrecker!

[astroimpulse]

Actually Gina...you make a great point about eye protection. It's worth wearing EP on the most innocent of jobs. It's amazing what damage small things can to to eyes. Just not worth the risk.

I don't care how I look...but I care how I see

Excellent point