New ROR build

[codemonkey]

Finally making some real progress on the new observatory. This time it's a roll-off roof and hopefully the last observatory I'll be building, at least for a very long time.

I've been slowly building most of the stud frames in the garage for months now. Currently on two weeks leave trying to get it all assembled and to lock up. My parents have come up to stay and lend a hand and I'm putting the old man (featured in several of the below photos) to good use.

Of course, I realised we left off the wall wrap as we were putting in the final nails in the last bit of cladding. Not sure if there's much point putting it on the inside of the stud walls...?

I'm posting this while taking a brief respite from the sun, and am about to head back out again and dig the next hole for post supporting the remaining rail.

[glend]

Don't worry about wall wrap, mine doesn't have any either. In fact it breathes better, no condensation build up between the exterior wall and the plastic. As long as you have a good exterior paint on the outside it will stop rain penetration into the cladding. A couple of things I will suggest:

- your wall should be braced diagonally, but that should have been done before the cladding went on. Some will argue that if you use something like plywood exterior cladding that bracing is not required, and if your using structural grade that is fine. Also look at getting some wall tie plates from Bunnings, just hammer them in to the top plates at the corners

- I would suggest putting some 45 degree timber braces between the walls at the top of the wall. Just short angles to brace the corners, they don't interfere with use of the observatory and can be used as roof tie down points. Since you do not have roof framing attached to the walls you need to make the top of the walls as stiff as possible.

- Consider lightweight roofing alternatives to colourbond, something like SunTuff Polycarbonate panels (easily cut and warrantied for 20 years).

- Give some thought to drainage, as your building on a slab with high ground behind the Obs.

Good luck. It seems about the same size as mine.

Glen

[codemonkey]

Thanks Glen, all great advice!

re the diagonals, I intend to add bracing ply to the interior of the stud walls as well so hopefully that will be sufficient.

Definitely adding some timber braces in the corners, haven't got there yet though.

I'm going with colorbond roofing; I've already got it sitting up next to the observatory waiting to be installed. I went with a light-coloured colorbond because I got the impression that it will keep the interior cooler than would polycarbonate which is what I was originally going to use.

I'm planning to dig in some ag-pipe for drainage. The roof pitch is angled such that rain will run off away and down hill from the observatory so hopefully that will help too.

Meanwhile, here's some pics of the most significant bits done today; roof structure on! Between my father, my wife and myself we *just* managed to get it on. Doesn't look like much but the structure was damned heavy.

[RobC]

Looking good and impressive. When you are finished you can come and build mine. What sort of cladding did you use for the external walls ?

Cheers

Rob

[codemonkey]

Thanks Rob! lol. I don't think you want me to build yours, mine only got dodgier and dodgier as the build continued.

The cladding is James Hardie Axon which is a styled cement fibre panel. It's relatively heavy, but easy to work with.

In the dome I had ongoing issues with condensation on the optics, but I think moving to the cement fibre panelling has finally fixed that. I just checked on the optics again this morning and with a forecast of 100% relative humidity, the optics were still nice and dry.

Of course that means the inside of the observatory is warmer than the outside, which has pros and cons. Now cool down is something I need to consider. I've had relatively poor seeing since using the new observatory and now I have to wonder how much of that is due to local seeing effects cause by the panelling retaining and radiating heat. Still, I'd rather have my optics free of fungus.

[cometcatcher]

Nice one Lee! Yeah it doesn't take much for the roof to get heavy. Are you going to insulate the inside of the roof?

[codemonkey]

Cheers Kevin. I had intended to insulate both the roof and at least the eastern wall, but I'm undecided now.

I only wanted to insulate to slow the rise of ambient temps in the morning sufficiently so that dew no longer formed on my optics, and that seems to have been resolved without adding insulation.

I want the best of both worlds -- slow to heat up in the morning, fast to cool down in the evening. I'm not sure if the insulation will make things worse now.

[glend]

Definitely insulate the roof, but you might be surprised at how something cheap, like folded aluminium batt panels (from Bunnings) work very well. I was going to use 30mm foam panels but installed the folded (accordion style) panels first. They allow an air gap under the roof panels and prevent condensation buildup under the roof.
Also consider a small extraction fan and place it up high on your roof wall near the peak. I use a good PC case fan, runs off 12v, and if you connect it to a small solar panel it will start up automatically when the sun rises. There are also small solar powered fans on ebay designed for vertical mount but many are junk, with pathetic air flow and run at about 5v.
A door louvre vent, at the bottom of the door, can assist ventilation and give the fan a source of air to pull through.
I run a small remote wireless weather station in my obs, so I can keep an eye on internal temps and humidity in the obs from the house.

[glend]

One other point, your pier, concrete or steel, will be a condensation magnet that can mean your mount head sweats as a result. The pier cools the mount head. In winter I have a mount head shroud that i made that has a small light bulb inside, this protects the mount head from condensation buildup. If you live in a high humidity environment it could be essential. If a mount is sweating or condensing on the outside, there is a good chance it is inside as well.

[codemonkey]

Thanks for the advice Glen! :-)

I used a small PC fan wired directly to a solar panel on one of my previous endeavours and had considered it for this one too.

I'm not currently getting any condensation on the mount at all, even with mornings where the relative humidity is 100%. You can feel the difference in temperature walking into the observatory in the morning, it's noticeably warmer than outside so I think it's keeping the equipment above the dew point.

I probably will install some insulation, but I'll wait until I'm having a problem that it solves first.

[alan meehan]

HI Lee your roll of roof obs looking good ,I used lightweight sheeting on my roof but under it I put some marine ply worked a treat for insulation and weather proofing also where your rollar beams come from the shed outwards put some angle bracing for the weight of the roof when you roll it off that timber is the same as mine and it tends to bow over time

[ZeroID]

Same here, ply roof with corrugated roofing plastic on top. Gives an air gap and has a thermal insulation effect or maybe isolation. Very effective and the painted ply is a very light colour too.

[Jen]

Looking good there Lee :thumbsup::thumbsup: it’s exciting isn’t it 👌👌 I cant wait to set mine all up 😜🤩