Observatory Build Underway

[malc-c]

Oh yes.. didn't include them in the sketch - my bad

[Gina]

A 5ft wide roof may be alright, it depends on what's below it and also how protected from the wind it is. With wind blowing from the lower side, water will be blown onto the wall in addition to the rain, causing additional weathering. If it's lawn or flower beds underneath these will disperse a certain amount of water. I'm having a roof just over 8ft wide with corrugated sheeting which will concentrate the rainwater into a row of jets. Now I could bring the roofing out further on a framework to provide a canopy but I think guttering would be easier. I've put lots of guttering up - it's no problem - just arrange sufficient (and continuous) slope so that the water runs well. Oh and use enough brackets so that plastic guttering doesn't sag in between.

Regarding flooring, I was thinking of providing extra support in the middle of the span, particularly for the 8ft run of joists. I don't mind a bit of give but too much is rather disconcerting. Admittedly, in general I do tend to over engineer. Not that it's such a bad thing, just adds a bit to the cost. Better to err on the safe side.

[Digz]

Regarding flooring, I was thinking of providing extra support in the middle of the span, particularly for the 8ft run of joists. I don't mind a bit of give but too much is rather disconcerting.

I would definitely provide central noggings on any span of flooring except relatively short spans, say 3ft or less. The centre of the span is where it is going to twist and deform.

Having said that if you plan to cover the joists with a sheet material, say ply, then providing adequate fixings to all joists, this will turn the floor structure into a diaphragm thus making the central noggings not as crucial.

One thing I am considering is making sure my floor is independent of my pier base. For example, the joist span either side of the concrete pier base (and don't touch it) and are trimmed around it, thus any movement, imposed or dead should not affect the pier and its base.

[Digz]

Just one other thing, which may be useful in the future - span tables. These can be found on the internet and I've attached one below for reference.

KD C16 Softwood Span Tables.pdf

[astroimpulse]

One thing I am considering is making sure my floor is independent of my pier base. For example, the joist span either side of the concrete pier base (and don't touch it) and are trimmed around it, thus any movement, imposed or dead should not affect the pier and its base.

Indeed. It's the first rule of Obs building.

I don't think anyone has done any different, to be honest.

At least we hope not

[astroimpulse]

Just one other thing, which may be useful in the future - span tables. These can be found on the internet and I've attached one below for reference.

That's pretty handy. Nice one

[Digz]

Indeed. It's the first rule of Obs building.

LOL, just got a soundbite of fight club now......

The first rule of observatory club.......

That's pretty handy. Nice one

They certainly are handy

[malc-c]

Using those tables the max span for max weight for 47mm x 150mm at 400mm centres is 2.96m. The span between the walls on my build is 1.88m so I should be fine, but as there will be enough off-cuts to form noggins I'll used them, and my 18mm sheet timber floor will also be screwed to the joist so the floor should be nice and stable. The pier will have an air gap around it between it and the floor, so there should be no chance of interference

[Digz]

Sounds spot on to me

[astroimpulse]

One thing I've seen people do, which is cool, is put some fine mesh around the pier hole. Not connected to the pier...just around the hole and down.

Stop creepy crawlies like wasps etc.

[Astrokev]

I've read that some folks put a layer of expanded polystyrene in the gap for the same purpose. When I eventually get round to planning / building my own obs (when....!) I currently envisage having the central hole around the pier covered by a separate hatch (for access), that's cut in 2 halves with a semi-circle cut-out in the centre, that fits closely to, but not touching, the pier itself. A thin length of foam would fill the small gap around the pier. With thought, I guess there's several ways this could be achieved.

Edited May 30, 2011 by Astrokev

[malc-c]

I'm planing on using some strip brush, the sort of thing you find used for draft excluders. I've seen loads on the net, just need to find a local souce

[Astrokev]

I'm planing on using some strip brush, the sort of thing you find used for draft excluders. I've seen loads on the net, just need to find a local souce

Good idea.

I was thinking of maybe trying strip brush to help "seal" the gap between my ROR and the walls to help keep out bugs etc. Not sure whether this would work, but feels like it should. I'd be interested in knowing whether others have tried it for this purpose.

Kevin

[astroimpulse]

I think if you use synthetic brush it'll be a fantastic solution. It should really keep everything out. Wind, moisture and bugs

[malc-c]

Well it's been a productive day today. Flooring materials arrived and I've found a local machine shop that has agreed to make the two plates for the telescope mount, which hopefully will be completed by the end of the week.

I've still got to complete the noggins between the joists and then will give it a coat of green wood preservative before laying in the conduit for data and power to the pier and covering it all with 18mm ply, but even at this stage the base is rock solid

[astroimpulse]

It's looking perfect

I wish my floor beams were that solid in my house :)

[Gina]

Oh yes, I think that would do any house proud! Looks great

[red dwalf]

very impressed so far.

great effort

[msinclairinork]

yes..impressive stuff Malc!

Keep up the good work!

Michael

[Digz]

Looking great

[Viv]

Malc - some great progress & work - nice one

[malc-c]

Another day and more progress...

Cut and fitted all the noggins between the joists, then battened out the last 8' where the warm room will be and installed 50mm Jablite insulation board (basically fancy polystyrene !) before fitting the flooring (18mm redwood core exterior ply). I then fitted two 22mm pipes with draw cables for the data and power to the mount. The flooringwas finished, leaving the area around the pillar with and access hatch (it was also easier to fit a small cover over the pipes rather than a large 8' x 7' board !)

Once the floor was laid it was given a coat of preservative to keep it waterproof in the event of any showers we may have before I can get the walls and roof on. Last thing was to set up the 200P and do some test height for the pier. This was cut at 90cm, which by the time the plates are fitted should allow between 15 - 20 degree horizon to the south with a 1.6m wall

Not sure if I'll be going for a 1.6m wall all the way along and then have 400mm side walls on the roof section, or have a cut in the track and have a drop side and keep just the roof section. The latter has the advantage of a higher structure strength and less weight to the roof section.

[Digz]

I am getting soooo jealous now....cant wait to see how it progresses

[Earl]

Looking Excellent !!!

Im chompin at the bit to start mine.

[malc-c]

OK - I've run out of screws (200 ) so I've stopped for today. Been slow going mainly due to the heat (almost hit 24c today !) and the fact that I'm as red as a lobster !

So far I've built 4 panels of stud work... and it's all level and square !!!

Oh and Gina (or anyone else looking for timber), I would think twice about ordering from Wickes... a fair few of the lengths I had delivered are twisted, and a couple bowed like a banana - It's made for selective choice of which lengths to use for the long uprights.