Gina's Observatory

[malc-c]

I must admit I was thinking I had made the wrong choice with 63mm x 38mm studding as there seemed to be a fair bit of movement. But that was before I used diagonal bracing. With the studding at 16" centres, and at least two opposed diagonal braces per panel the whole frame has now become ridged.

Having said that , using 75mm x 50mm studding would ensure you have a rock solid structure, and would only add to the cost slightly

[Astrokev]

I must admit I was thinking I had made the wrong choice with 63mm x 38mm studding

Malcolm, I'm sure your build is sufficiently robust but, if you had to start again, would you keep with 63 x 38 or move up to 75 x 50 ?

[malc-c]

Malcolm, I'm sure your build is sufficiently robust but, if you had to start again, would you keep with 63 x 38 or move up to 75 x 50 ?

75x50mm would give a wider base for things like tracking, and as there is a grater area at the end of the wood the but joints would be stronger, but it depends on the design. If you are building a small observatory, with no warm room then 38 x 63 is fine. 75 x 50 would be overkill on a 6' x 6' project. If I was going large, say 12' x 12' then yes 75 x 50 would be used, but on anything less 63 x 38 is adequate especially when braced.

One thing I would do different if I could would be to source the material and select the lengths I needed rather than rely on it been picked and packed by someone in a warehouse who isn't selective about the quality.

[Gina]

Time for a break - been digging out more soil.

Been considering comments and suggestions and have yet another design idea

Since my overall design is for a roll off top section rather than just the roof (to give lower views of the sky), the weight of the roll off section will be greater than just the roof. Therefore I think the load bearing track needs to be more substantial. The main force will be downwards while the rigidity of the base, being lower, will be better.

With a lower structure for the base of the obsy I think 63x38mm studding will be quite adequate. Same for the roll off section where the weight wants keeping down. The roll off track needs separate supports where it overlaps the warm room as it will be away from the warm room walls. This results from the track being below roof level. At the same time, I'm planning a smaller warm room than the obsy. Consideration of the size of roofing sheets makes the roof of a 6ft square warm room a lot easier, requiring just 2 full sheets. I think 6ft square should be quite big enough - many are this size or smaller. I propose to use it to house computers for mount control and imaging. These will be standard base units standing on the floor with a worktop above something like 18-24" x 6ft. This will be on the south side where the roof will be lowest.

I'm thinking of fence posts for the track beams because they're designed for outdoor use and rot proofed plus strong enough to cater for an unsupported length of 6ft. Two 2100mm posts joined together (inside the obsy area) gives 4200mm - the length of the track I'm proposing. The ro section will be supported on 4 wheels each side when closed but on 3 wheels each side when open. This saves space and improves the appearance, the ends being level with the warm room end wall.

The track beams can be supported on fence posts at the open ends with stays across to the warm room walls. As for other (corner) fence posts, I haven't decided yet. But I agree that if I do use them they can sit on top of the flooring. Screws down into the flooring and joists will be quite adequate to hold the bottom.

[nightvision]

I notice you have plenty of space, would it make the whole design cheaper and easier to engineer if the obs roof rolled off away from the warm room?

[Gina]

I notice you have plenty of space, would it make the whole design cheaper and easier to engineer if the obs roof rolled off away from the warm room?

Not really plenty of space - I don't want to take up too much area. Without the warm room to brace the track beam onto, it would need more timber.

[Astrokev]

If I was going large, say 12' x 12' then yes 75 x 50 would be used, but on anything less 63 x 38 is adequate especially when braced.

One thing I would do different if I could would be to source the material and select the lengths I needed rather than rely on it been picked and packed by someone in a warehouse who isn't selective about the quality.

Thanks Malcolm.

Not sure how big my design will be as yet, but definitely smaller rather than larger, so the smaller timber will probably suffice based on your experience. Cheers.

You're right about needing to select wood yourself. Amazes me how warped most of the stuff you get from the chains is.

Kevin

[Digz]

One option to consider with the use of fence posts as corner posts, is that you could extend your sole plate so the corner posts sit on this and can be tied in like the attached.....

[Gina]

One option to consider with the use of fence posts as corner posts, is that you could extend your sole plate so the corner posts sit on this and can be tied in like the attached.....

Yes, the corner posts will go at the corners of the flooring.

[martin_h]

I used 6"x2" for my floor beams, mainly because its built into a deck. 20 people on it at one time - no bounce!. 4"x2" for the studwork, I wanted the warm room insulated and most insulation is 4" thick and fits nicley into it, 3" and you will have to pack the insulation and loose some of the value.

I used 18mm OSB for the floor and roof with 2 layers of felt on top.

[Gina]

I might consider insulating my warm room too.

[martin_h]

I might consider insulating my warm room too.

Well you'd want it warm wouldnt you?

I have a couple of these in there as well....keeps the chill off

Sunhouse Tube Heaters With Fitted Plug :: Tubular Heaters :: Tubular Heating :: Heating :: CNM Online

[Gina]

A warm room kept warm would probably be nice

[Gina]

More site excavations today. No! I didn't use the spade - if you look carefully you can see tyre tracks

1. The hole for the pier base

2. Digging out for floor foundations.

3. As 2. from another angle.

[malc-c]

Making progress Gina

[Gina]

Coming on slowly

While in town this morning I had a look at fence posts in Homebase. The first one I pulled out was dead straight. Good I thought. Then I took out some more and they were all a bit warped. I gave up after 4 or 5. If I do use any I shall have to be very selective. I'd say they had about 20 or 30 of each size. I don't think I shall use them for the corners but might possibly for the track support. Depends what I can get from the sawmills. Had no reply from my email so I'll ring them tomorrow to see what their prices are like.

Did a bit more excavating this afternoon and evening. Think I'm nearly there.

[Gina]

Also looked at other timber in Homebase. Plenty of 2.4m lengths. Their prices were at least twice or three times Wickes! If the local stuff proves too expensive I might take a trip to Wickes at Taunton (25 miles round trip) and select some, I can get a certain amount in my car.

[malc-c]

Like I mentioned before out of the 100 lengths of Wickes studding I had 3 which were trash, in that they were split from the end to 1/3rd the length, or had been damaged by the band wrap machine. 7 other lengths were bowed or worse twisted. But to be honest I can't be a$$ed to argue the toss with them to get £20 back... I'll select 10 perfect lengths from B&Q to complete the build.

You should get a decent square true set of posts and studding from a saw mill or timber merchants..

[Gina]

Phoned the sawmills this afternoon. Timber is cheaper than Wickes, plywood about the same and OSB just a bit dearer (£12.25 v £14.30 for 8x4 11mm). Actually, I think the plywood is cheaper from the sawmills as that was pressure treated price. The sawmills sell in 4.8m lengths so there would be less waste. Also, I can have a continuous length for the running track support instead of having to join it. They charge £20 for delivery for orders under £300.

I've had another look at the roof design and decided corrugated bitumen is not the best option. Two reasons really. 1. It needs at least 10degrees slope (1 in 6) making the high side higher - I think felt can be at 1 in 12. 2. Sealing the corrugations against wind blown rain is difficult. Everyone else seems to use felt - must be a good reason

[malc-c]

They charge £20 for delivery for orders under £300.

If you have space for storing it, ordering all the materials in one go and storing them on site will be better and keep delivery costs down as you would exceed the £300 by miles

It also helps with the logistics of the "just in time" ordering which can hold you up !

[astroimpulse]

Ooh, 4.8m lengths is good. Sounds like you've hit the jackpot with your sawmill

[Gina]

If you have space for storing it, ordering all the materials in one go and storing them on site will be better and keep delivery costs down as you would exceed the £300 by miles

It also helps with the logistics of the "just in time" ordering which can hold you up !

If I were to use shiplap it certainly would (I forgot to ask if they did shiplap, but I expect they do). A quick estimate of the amount of shiplap required would cost the best part of half a grand from Wickes! I now have to work out what I need and add it all up. Yes, I'll order it all in one go.

[Gina]

Ooh, 4.8m lengths is good. Sounds like you've hit the jackpot with your sawmill

Yes, that's what I thought

[malc-c]

A quick estimate of the amount of shiplap required would cost the best part of half a grand from Wickes!

LOL - it's not much cheaper from a builders merchant

50 lengths of 5.1m rebated ship lap - £421 !!!!

[nightvision]

LOL - it's not much cheaper from a builders merchant

50 lengths of 5.1m rebated ship lap - £421 !!!!

Managed to find good quality Redwood Shiplap at about £10.70 a square metre (good for north west obs builders following this excellent thread), should come to about £290 plus delivery:

Shiplap cladding (Redwood) - Pine (Skirtings etc) - Timber - Timber & Sheet Materials

and these seem good value for runner support etc:

http://www.savoytimber.com/garden-decking/decking-timber/150mm-x-50mm-6inch-x-2inch-treated-framing-timber/prod_143.html