7Wells Observatory Build

[old_eyes]

Man turned up this morning with a mega-machine:

Worth every penny as I did not fancy hand digging a 75 m trench 45 cm deep.

He was done and dusted in 1.5 hours including unloading and loading the beast and time for a chat about what I was up to.

The 5 m I had to do by hand, because I knew there was a culvert under the lawn somewhere, took me the rest of the day!

Now laying cable and conduit, but it turns out I can't do sums on how much sand I needed to make a bed at the bottom of the trench (think I got a decimal point wrong somewhere). It would be easiest to get a big bag and barrow it up, but they can't deliver until next Tuesday and my long suffering partner is making pointed comments about the size of the trench and the amount of soil everywhere. I foresee several visits to the builder's merchant tomorrow for standard sacks!

Still - onwards and upwards.

[old_eyes]

After a break for family stuff and appalling weather, got back to work this weekend.

Removed shuttering around concrete block. Found a little shirkage, but not too bad.

Weed suppressing membrane laid and pier mounted. Just needed one additional washjer on one side to get a nice level surface.

The next pixture shows base frame, constructed, squared, levelled and joists added. That took a lot of Sunday (lawns needed to be mown as well 😞 )

That's me for the weekend as the rain came in.

Next some noggins and then we start going up!

[old_eyes]

No progress this weekend as stifling heat was replace by steady rain yesterday and torrential rain today.

So instead here are the two tools that have made the work so far possible:

A modern impact driver and

These spectacularly aggressive self-drilling and countersinking woodscrews.

These are 6 x 80 mm screws with a Torx head. The head means they fit firmly to the driver bit so that I can pick up, align and drive one handed. Each screw takes about 3 seconds max to drive fully home. Considering the number of screws involved in the frame this makes life easy (or considering I have arthritis in my hands - possible).

I have also used some similar screws with a pozidrive head, but torx is much better.

Highly recommended if you are undertaking this sort of project.

[laser_jock99]

Pozidrive screws are okay so long as you use size 3 (or larger). The smaller size 2 is prone to rounding off either the screw or the bit. Torx is good though too- but again, the larger sizes are better for this kind of work.

[johninderby]

I always use Spax brand screws now. Their pozi screws never round off, even the 2 size, as the heads are hardened. Yes you pay more but worth every penny.  👍🏻

 

 

[old_eyes]

2 hours ago, laser_jock99 said:

Pozidrive screws are okay so long as you use size 3 (or larger). The smaller size 2 is prone to rounding off either the screw or the bit. Torx is good though too- but again, the larger sizes are better for this kind of work.

Using 4's and 6's so far. Not a single problem so far with Torx head

[old_eyes]

2 hours ago, johninderby said:

I always use Spax brand screws now. Their pozi screws never round off, even the 2 size, as the heads are hardened. Yes you pay more but worth every penny.  👍🏻

 

 

I am using Turbo-II's. I think they are Screwfix own brand.

[johninderby]

Yes with bigger screws rounding off isn’t a big problem. For smaller screws though worth getting the Spax. You can take them out and put them back in as many times as you want without any rounding off. Usefull when having to fit and refit something.

 

 

Edited July 30, 2019 by johninderby

[Swoop1]

When I was a school caretaker for a couple of years aftyer leaving TVP, I found that the Turbo Gold screws were brilliant. Our facilities manager sourced some with Torx heads and they were the best.

[old_eyes]

3 hours ago, johninderby said:

Yes with bigger screws rounding off isn’t a big problem. For smaller screws though worth getting the Spax. You can take them out and put them back in as many times as you want without any rounding off. Usefull when having to fit and refit something.

 

 

Which is my usual problem. If there is a way of screwing something in the wrong place or in the wrong orientation, I will find it! Sometimes my joints end up looking like swiss cheese or a bad attack of giant woodworm.

[old_eyes]

With a couple of days of good weather, progress has been made and the frame is more or less complete

Needed to trim some edges to give the uprights a chance to be upright!

So this is where I am today

Next job warm room roof, then side cladding then rolling roof. Annoyingly I have ended up 2.5cm out of square in the stud wall between warm room and toelescope room, but from the rest of the measurements, I don't think that will impact the rolling roof at all (well fingers crossed anyway).

[Gina]

My observatory isn't square either but it works.

[old_eyes]

18 minutes ago, Gina said:

My observatory isn't square either but it works.

I figure it will be good enough if I get the rails lined up properly, but it is irritating. I tried to be so careful!

[Gina]

Yes, I know what you mean!!!  Me too.

[JamesF]

Looking very good :)

James

[old_eyes]

13 hours ago, JamesF said:

Looking very good

James

Thanks James. I have followed your build thread with interest and learned much from the discussions between you and other experts (particularly the pointed questions to ask the electrician). I doubt my build will be quite as beautiful as yours, I don’t have the skills, but I hope it will keep the gear accessible and dry!

Have you thought of publishing your thread? It must be up there with Moby Dick by now! A driving narrative with sudden in-depth excursions into technical detail 😀

[old_eyes]

Last good weather day for a while, so keen to get the roof up and covered.

After a bit of heaving I managed to get the OSB roof panels on the warm room:

Then it was justa  case of laying out the EDPM, letting it relax into shape a bit and putting the adhesive on:

Stuck down the edges with contact adhesive and added the trim to produce a finished roof. Just in time for some real world testing from the approaching storms.

Actually I am not at all sure I got the target slope on the roof. Looks a bit flat to me. So will be interested to find out what story the rain tells.

Just the corner pieces on the trim left to add.

Edited August 8, 2019 by old_eyes

[JamesF]

It looks very neat indeed.  Let's hope the rain does roll off it nicely.  It should be more than adequately tested this weekend :(

James

[old_eyes]

We didn't get the promised storms lastnight, but it did rain steadily for several hours. 

I went out and checked this morning and although there were plenty of puddles on the ground, the roof was dry.

Whew!

[Gina]

Wet here and we had torrential rain in the night.

[JamesF]

27 minutes ago, Gina said:

Wet here and we had torrential rain in the night.

Didn't we just?  When I came down to unplug the router in the small hours, the patio was about 2" underwater.

James

[old_eyes]

Pretty quiet for us las night, but gradually ramping up now. It has reached heavy rain and making noises like torrential is next.

[Gina]

Torrential showers today and a strong wind getting stronger!  It's not nice out there!

[old_eyes]

Hmm! could be a test of how well the roof is tied down as well as whether it sheds water properly.

I had intended some ground anchors to make sure the frame does not move, but I can't do it in time for the predicted weather. Another unexpected stress test!

[old_eyes]

After a bad weather break, and some visiting relatives, I managed to get back to work today.

My plan was always to make the observatory as removable as possible as the area is intended to be a nature reserve after we have gone. For that reason the structure is sitting on decking risers placed on paving slabs and the only permanent structure is the concrete block for the pier.

I could rely on the weight of the building to keep everything steady, but we get some pretty strong winds here, and I was particularly worried about the whole shed moving sideways.

So I decided to add some ground anchors from Spirafix.

These are their 50mm x 1200mm anchors and are pretty substantial pieces of metal. Each rated to resist over a tonne of pull. I decided to put in four, one on each side. If those go I probably have bigger problems to worry about.

Insertion is pretty easy. There is a metal cap to protect the threaded hole at the top and then you just bash it in.

The site is on boulder clay and digging anything by hand has been known to make grown men weep. I was worried that they would jam, but they coped easily. Just using a small club hammer the hardest one to put in took under 5 minutes, and I was not hitting all that hard. The screw design seemed to cope with whatever obstructions they found.  I guess If I had managed to centre on a large rock I would have had to back out (they unscrew with a wrench) and try somewhere else.

Having driven them down to the right depth, it was simply a matter of drilling holes and bolting the L-bracket to the anchor and the frame.

Highly recommended.

I think that with three of four of these you could mount a pier directly and do away with the concrete block. Probably not cheaper than concrete, but a hell of a lot quicker!

Edited August 21, 2019 by old_eyes