Astrokev

It seems that votes are split - you pays your money and takes your choice. The problem with this type of question is most individuals only tend to have experience of a single material, rather than comparative experience, so the relative pros and cons are generally biased. Nature of the beast I guess ? I'll price up a few options and see if that sways my decision. What I think I have confirmed though, is that marine ply is probably not worth pursuing, having minimal benefit for a huge cost ?. Thanks to all for the feedback - very helpful.

Then again, many years ago I made a roll-off box out of OSB for the EQ mount I had at the time. Treated the outside with fence paint. Within a couple of years it was mush ?. It was only intended to be a short-term structure, which was just as well!

Not sure my budget would stretch to that, but they would look pretty!

Thanks Ray. Did you use marine ply? This is horrendously priced, so would like to avoid this if possible.

Thanks Lee. I know OSB3 is supposed to be water resistant but I still worry over it's use in an area that may get wet. I've seen some reviews where OSB3 has still swollen and disintegrated when it's got wet. Probably a dodgy supplier but still makes me nervous. That said I haven't completely discounted it yet! I will be covering it - probably with interlocking foam/rubber tiles, so the visual appearance isn't an issue.

Thanks Julian. I'll take a look, although chipboard sounds risky for a floor. I presume they're specially treated

Thinking about what flooring to fit. I want to use plywood, but wondering whether to go for 12mm or 18mm? Only a small difference in cost but every little helps! 12mm is also a bit easier to cut and work. What do folks think? Anybody used 12mm and would it do the job? In peoples experience, would standard ply be ok, or should I go for marine. The latter is obviously ideal, but in real life, is it necessary? I can't see the floor getting wet other than occasional heavy dew, and will be covered.

Drizzling this morning, so doubt there'll be much activity on the observatory today ?

Cold and the odd shower this afternoon but I desperately want to get the door on, so wearing 2 fleeces and my thickest woolly hat I braved the elements... Well, the good news is that the door fits the hole ? . The first pic is just the door free-standing in the frame, held in place with the plank and a nail in the top beam to stop the door falling through. After much puffing, panting and straining to get the door where it needed to be to mark the position of the hinges, I recessed the hinges slightly and then screwed the top and bottom in place with a couple of screws, to check for alignment. I was chuffed that the door moves quite freely, but the lock side doesn't quite clear the liner by about a millimetre (second pic). The gap on the hinge side is also too wide (a good thing to allow for adjustment) and is slightly uneven, being a bit wider at the top. I was pleased I'd only recessed the hinges in the liner by about half the hinge thickness. So, off the came the door again - lots more heaving and straining - and chiselled out another millimetre or so. The light was fading fast by this time so decided to pack away and try again tomorrow if I have time. Oh, and my friend was back. Spent the whole time I was out there plodding around the garden with her chicks. Clearly inspecting the quality of my work ?. Or, possibly eyeing up their roost for the night.

Ah, Slade - my favourite band back in the 70's. They were the first band I saw live, in Liverpool, and I've still not been to a gig that was louder ?. Their early stuff, just after they changed their name from Ambrose Slade and before they went glam, was much better than their later stuff.

Thanks James. I'll soon find out if they're up to the job. The hinges may be fine; I just hope the door liner is too! Yes, the birds are peafowl. Next-door-but-one neighbour has a wildfowl collection and lets a group of peafowl wander the village - a few cocks and several hens. Now that the young are about, it makes for entertaining driving sometimes! I had them nesting in the back garden several years ago under a rosemary bush (that was pre-dog). Very noisy as you say, and visitors to the village are always really surprised to see them. Here's a peacock in the front garden taken a few months ago. Beautiful birds. I'm sure once the observatory's finished it won't be long before they're using the roof as a sun-trap. That should make for an interesting photo ?

Thanks Kev for your kind comment, but no need for jealousy. My build is totally over-engineered just to give me something to keep my mind engaged. Sometimes I wish I'd taken a more reasonable approach. If I had it would've been finished ages ago and I could be using the thing! And possibly more importantly, it would have still been completely fit for purpose! I'm sure yours is great. If it keeps your gear dry and lets you look at the sky then it's fit for purpose, which is what matters most.

Update on today's work - what there was of it. The plan was to get the door hung. Not sure what happened to that idea. Important stuff got in the way, as is often the case, and I didn't get outside until well after lunch. But, I did manage to get the hinges on the door. I went for parliament hinges which, by design, have the screw holes further from the hinge pin than conventional hinges. This means that I can put the screws through the edge trim and then into the solid 3x2 frame that lies behind it, rather than through the edge trim and then into cladding. With the weight of the door, I was worried that taking the weight on the edge trim / cladding combo may have been risky. I've also up-sized the screws from the 1.25", that came with the hinges, to 1.5". The light was fading as I finished, and I couldn't face man-handling my 2-ton door into the doorway in half-light, so stopped while I was ahead. In the last 30 minutes before I couldn't see anything I cleared some hard packed soil from under the joists where the drainpipe conduit will go, linking the pier with the warm room. Tried the drainpipe for size and all seems in order, so a bit more progress made on the pre-work for the floor. A bit off topic, but the other pic is of a few visitors to the garden this morning while I was having breakfast. Rubbish picture taken through a dirty kitchen window, but it made me smile. Perhaps they were eyeing-up the observatory as a roost !

The only small issue I have with the door is the weight. I can't believe that a few lengths of 3x2, a sheet of ply and bit of cladding can weigh so much ?. Perhaps it's the rock wool insulation ?. i just hope the frame and hinges can handle the weight.

Great to see the roof on James! Although not glued down, it's obviously now weatherproof. With the generous overhang you've designed in, it should do a great job of helping keep the inside dry. I was really chuffed when I reached this stage. I was getting so fed up of hauling the wet tarp on and off the roof. Hope you manage to get the walls covered before the weather really starts to turn south ?

That's a fair point which I'll need to watch for. Although it's screwed into the floor joists with 4" screws, I'm more nervous about the sill slowly working loose due to constant stepping on the unsupported edge. I will be making a raised step which will be almost the same level as the sill and, in reality, I think I'll step right over the sill to enter/ exit the warm room.

Maybe, we'll see, but then I did start in July 2017 ! ? but like I said, I can't see me having permanent power until next year. I'd like to hook up power to 3 outbuildings spread around the garden, and I just can't see me getting round to that for a while yet. No worries, I'm happy to run off an extension cable for a while.

I must admit, the same thought occurred to me when I screwed it down. Don't worry, I'm sure it won't last ?

Yes, couldn't agree more. It certainly keeps me motivated ? Not that it's a race of course, but with possibly the longest build on the forum, I don't think I could stand the embarrassment if you guys beat me to the finish line ?. At least for the main build anyway; I suspect it may be a while before I install a permanent power supply and will probably be running off an extension cable for a while. Keep going Alex and James - your builds are looking great.

As promised, a few pictures of today's progress. Forgot to mention earlier, but I also installed the door sill. This has been sitting pretty on my dining table for the last week after being treated and varnished. Good to get it finally on the observatory; we can use the dining table again now - although to get to it you have to climb over my telescopes and boxes of associated stuff. Oh, and my sons drum kits and various other percussion related equipment. Why couldn't he have learned the guitar like his dad - far more civilised and takes up a fraction of the space ?. Thanks once again to @RayD for allowing me to copy his door design ?

Lovely sunny day so skipped lunch to try and maximise the few hours that we get at this time of year. Even so, I still didn't manage to get as much done as I hoped. Spent an age pondering on where to put the lock on the frame. Ideally, I wanted to put the mortise into the main timber frame, but the presence of the cladding was making this difficult without putting the lock so deep that the keep wouldn't have been flush with the edge of the door frame lining. Anyway, finally made a decision and fitted the lock. Then added insulation, breathable membrane, and fitted the cladding. Didn't get the hinges on, so a job for tomorrow. The finished door is really heavy so a bit concerned that the hinges and frame may not be able to hold it! Resting in front of the TV at the moment, while my daughter kindly makes dinner. Will post a few pics later if I can drag myself out of the comfy chair ?.

I always try and take pics at all stages of my build too, for the same reasons. I've got hundreds on my PC but only post a few to SGL. My comment was just acknowledging that on this occasion James was clearly too pushed for time to get the phone out - and that's fine. With my build at the moment it's a race to get stuff done before the light goes. I skipped lunch today to maximise the daylight hours. I was really just trying to say that if it's a toss-up between taking a few photos and finishing a task then I think the latter is sometimes more important. Having a few photos of an unfinished task can be pretty frustrating, especially if you're working on your own and time is so precious ?.

Planning to get it hung over the weekend - keeping everything crossed. Hope it stays dry down your way. Weekends are precious @JamesFand I hope you can make the most of it !

The weather was supposed to be dry today, so was gearing up to work on the build but, as it happened, there was constant really fine drizzle all day. Thanks Mr. Weatherman - wrong again! I managed to cut the cladding for the door but then retired inside the observatory. I don't like working in the wet! So, spent an hour clearing the inside of all the off-cuts, spare timber, and general accumulated rubbish. I can actually walk about inside now, albeit on the joists. My priority is to complete the door to finish making the building fully watertight, but when this isn't possible I can get on with internal jobs now that I can move about without tripping over stuff. My aim is to have the observatory usable within the next few weeks, as I want to do some imaging of comet 46P, so the flooring seems the next job when I'm not playing with doors. The pic is just a quick snap to show the arrangement of door cladding. It's not fixed in position as I still need to soak the end timbers in preserver and also insulate the inside of the door cavity. Tomorrow is forecast for sun all day, so I'm hoping it will at least be dry enough to work outside.

Well, after a few days of being tied up with other jobs, this afternoon I managed to spend some time in the local DIY emporia. Bought a 5 lever lock and door handles, some parliament hinges, and a load of insulation. Tomorrow I'll be spending some time getting acquainted with the main observatory door ?.