JamesF's observatory build

[ollypenrice]

15 hours ago, JamesF said:

 

@ollypenrice has long been a proponent of the welded frame rolling roof, though I'm not sure he ever had something quite this large in mind

It was my plan to lift the roof into place as soon as I'd finished, but I'm lacking "volunteers" to help lift it this afternoon, so that may have to wait until the weekend.

James

That's a great use of the material and I wouldn't hesitate to go for it as you've done. Mine's about 2.2 x 2.5 metres and has resisted everything including a flight and crash landing when two crappy anchor bolts turned out to be tat and sheered in a violent wind. Once picked up and put back on, the steel chassis was entirely undamaged.

Regarding the roof material, I'm totally and unequivocvally wedded to corrugated galvanized steel and won't entertain anything else here, having tried the usual alternatives - all of which are flawed. Corrugated steel is totally waterproof, effectively everlasting and can be bolted down hard so it will neither tear through its anchors nor fly off. While it is noisy inside as the rain hammers down on it, the idea that it makes a noise audible outside is pure mythology. Next big job here will be to get rid of the useless rubbery-plasticky corrugated sheets on the big robot shed and replace them with steel. In less than five years the synthetic ones have started to tear off and distort while my oldest steel roof, which will be fifteen next birthday, is still absolutely perfect. I just have rigid insulation panels on the inside to counter the condensation. 

Our system here is to house our astronomers in the farmhouse: how many bedrooms will you install under that magnificent roof in the observatory??? 

Olly

[JamesF]

11 hours ago, ollypenrice said:

I just have rigid insulation panels on the inside to counter the condensation.

If that works then it's very tempting to give it a try.  It might even be tempting to make the sides from the same material rather than wood.  The ridge pieces with the system that Davey-T linked to are apparently 130 degrees with up to 15 degrees flex either way and as the ridge and roof-to-wall angles on my design are 120 degrees that ought to work out nicely.  Thanks to the low weight I could even potentially make a little "porch" for the door that would be part of the rolling roof.  Coming up with something that works for the warm room roof (in particular stopping rain being driven under the rolling roof) might be more tricky, but I could still go with EPDM for that.

I shall ponder on this further as I get the roof up onto the walls.

James

[Davey-T]

These folk have various profiles.

Forgotten how to shorten links 

Dave

https://www.ebay.co.uk/sch/macclesfieldcladdingsuppliesltd/m.html?Category=66945&sellerName=macclesfieldcladdingsuppliesltd&_sacat=66945&_trkparms=pageci%3A6631d812-cd8f-11e8-98af-74dbd1808994|parentrq%3A64b16c931660ab672c1280e1fff70ba9|iid%3A1

[Swoop1]

Commercial premises the country/ world over have their roofs clad in plastic coated sheet metal. When I were a scaffolder, I didn't once get killed by falling through one of the roofs. I should imagine this material would do the job nicely james.

[JamesF]

Well, it's still raining on and off here and over the last 24 hours the forecast for Sunday has gone from "dry with some cloud" to "tipping it down all day", so I don't think much is going to get done this weekend

James

[Gina]

Rain has stopped and we've even got some sunshine though still plenty of clouds about.  Wind has eased off a lot to just a strong breeze.  No damage from this last storm thank goodness.

[Gina]

Oops - spoke too soon - wind has got up again in gusts of near gale force.

[JamesF]

Yes, we had a brief period where the sky changed from grey to blue, but that was over within about twenty minutes and the wind has picked up quite a bit.

James

[JamesF]

By chance I just caught child number one in his wellies as he came in from feeding the chickens.  Overruling his protestations that he wasn't strong enough to help I press-ganged him into assisting me to lift the roof into position.  As things turned out it took less than ten minutes, resting one end of the roof on the walls, then "wiggling" it up to the point where the first set of wheels would drop onto the rails at which point it was just a question of lifting the other end horizontal and rolling it along until the second set of wheels was on the rails.

Standing inside it now feels like a huge space.  The total height of the walls including the sides of the roof must be about 2.2m.  The positive side to this is of course that I'm very unlikely to have a telescope that will need moving out of the way before the roof can be closed.

James

[Gina]

That looks very impressive James

[JamesF]

Thank you, Gina :)

I had a quick check of the total wall height.  It's actually 2.08m, or a smidge under six feet ten in old money.

James

[Alan White]

James, wow my man, that really looks stunning.
I had wondered how it would start to come together, wonder no more.

So what roofing are you now going for?
or are you sticking with rubber on wood?

[JamesF]

I'm still dithering over roofing material.

Metal sheeting certainly appeals if condensation can be controlled by using insulation as Olly suggests.  The design of the warm room roof however doesn't quite lend itself to the same solution because there's insufficient clearance between the sides of that roof and the sides of the sliding roof for any covering that isn't flat.  That was a deliberate design choice to make it easier to prevent rain being driven between the two when the roof is closed.  I might however be able to find some zinc-coated sheet that could be bent to fit the sides and lap under the metal sheet roof on top.

James

[JamesF]

Just discovered a slight negative side to using metal sheeting for the roof: the cost of delivery.  Even the closest place I've found so far want to add over 25% to the order for delivery (because it's a fixed price and I don't need that much).  I might have to look at how practical it would be to pick them up.

James

[Astrokev]

Ouch!

[JamesF]

Quite   The company Davey-T linked to (who I could collect from if I took the day off) also have a three week delivery timescale and warn that it may be even longer for small orders such as I'd be making because they'll wait to piggy-back the manufacturing on a larger lot.  Some other manufacturers won't deliver small orders.

Unless I go for standard uncoloured wriggly tin sheets, which I'm seriously not keen to do as they're really not attractive and the window over the kitchen sink looks down onto this roof, it's not looking too hopeful.  It's hardly the end of the world though as it wasn't the original plan anyhow.  It was worth looking into and definitely worth consideration if there's a suitably local supplier, especially as I've also discovered that it's possible to buy sheets with an anti-condensation backing.

James

[Gina]

That's often the problem!!

[Horwig]

On 13/10/2018 at 14:59, JamesF said:

I'm very unlikely to have a telescope that will need moving out of the way before the roof can be closed.

James

Oh come on, why so negative, 20 inch Newtonian maybe, nothing like another challenge. After this obsy nothing will seem impossible?

 

Huw

[JamesF]

7 minutes ago, Horwig said:

Oh come on, why so negative, 20 inch Newtonian maybe, nothing like another challenge. After this obsy nothing will seem impossible?

Huw

Were I to have such a beast (and it is certainly not impossible) I think I'd build an obsy specifically for it

James

[Davey-T]

These folk claim to be cheap and you can collect.

Dave

https://www.ebay.co.uk/itm/Very-Cheap-Box-Profile-Steel-Roofing-Sheets-Moorland-Green-Metal-Roof-Cladding/192203301073?_trkparms=aid%3D777001%26algo%3DDISCO.FEED%26ao%3D1%26asc%3D20160801204525%26meid%3D0709eeef14384abeb015aa04608d5d1b%26pid%3D100651%26rk%3D1%26rkt%3D1%26%26itm%3D192203301073&_trksid=p2481888.c100651.m4497&_trkparms=pageci%3Aa8f461fe-d0bb-11e8-982f-74dbd180c2ce|parentrq%3A797ca8071660ac1f5c2d11d9fffc4f42|iid%3A1

[JamesF]

9 minutes ago, Davey-T said:

These folk claim to be cheap and you can collect.

Sadly it's still a 300 mile round trip with a trailer, and a day off work unless they happen to be working on a Saturday that's convenient to me.  I'd probably be better off going to that first place in Oakhampton.

James

[Oddsocks]

Hello James.

There are ~five Travis Perkins depots within twelve miles of you that can deliver plastic-coated galvanised-steel low profile  sheet roofing panels in two colours, grey or green, and three lengths, i’ve linked below to the shortest length they do in green.

https://www.travisperkins.co.uk/Steel-Roof-Sheet-BS12B29-Juniper-Green-Plastic-Coated-Sheet-6ft-(1825mm)/p/766965

The only issue with TP is they don't stock and are unable to supply the matching ridge cap and barge board panels so you have to find a solution that works for you for the ridge cap, I don’t know why TP don’t supply these, we did email them several times but answer came there none! No wonder TP are always in some kind of financial mess.

Things they don’t tell you in the technical specs:

The panels expand and contract a large amount with temperature change and when the panels are nailed or screwed to the roof only the first fixing hole at the top of the sheet should be a tight fit on the shank of the fixing, all the holes below it should be drilled oversize, at least twice the diameter of the fixing shank, so that the panel can move as it heats up, otherwise the thin panel will warp and lift and never sit flat on the roof.

If you have to cut the panels to length the cut ends should be painted with a flexible sealant, such as bitumen or a silicone rubber as even though the steel is galvanised before coating it will gradually rust inwards from the cut and delaminate, the cut ends should be hidden under the ridge cap or under overlapping sheets when used on long spans.

When used on a battened roof you can’t walk across the panels, the TP ones are too thin and will crease, the panels used in commmercial builds are much thicker and stronger. The TP panels are ok to walk on when laid directly on a supporting board.

The open ends of the corrugations at the eaves and at the ridge need closing with a mesh so that wasps can’t set up home in the corrugation voids but there is still some ventilation under the panels.

The grey coloured panels are better at keeping cool, the green ones look good but get very hot, both are better than black rubber or felt though for helping keep the inside of the building cool, especially if you use mesh guards at the corrugation openings rather than foam inserts to maintain airflow.

HTH

William.

[JamesF]

Thanks William.  I think it's all getting too complicated now though.  I think I'll revert to the original plan and go for the EPDM.

James

[Oddsocks]

10 minutes ago, JamesF said:

I think it's all getting too complicated now though.  I think I'll revert to the original plan and go for the EPDM.

The EPDM is certainly easier James.

The flat, low-profile corrugated steel panels look better and probably last longer but installation on a ridged roof is complicated unless you can get all the components needed from the same manufacturer.

We re-roofed the scout hut with metal panels two years ago, previously it was felted but vandals set the roof on fire and we thought metal was less of a liability.  We had to cancel the TP order though when we found they didn't stock the ridge caps and barge boards.

One of the scout assistants knew somebody in the trade and we bought enough 1.6mm thick sheets in blue to cover the 4m x 6m hut, with matching barge boards, ridge caps, and corrugation meshes, and got free delivery, from a company in the Midlands. I seem to recall the final bill was around £500 though.

My neighbour has re-roofed his garage with TP panels in grey but that is a flat roof with just a six degree fall so no need for ridge caps and the barge boards are all treated timber plus he didn't need to cut any of the panels so a much easier job.

William.

 

[Gina]

Yes, the ridge is a problem with metal roofing and edges too.  Best not to cut steel sheets as the ends rust as has been said.  Ridge and edges are no problem with EPDM and fitting is fast and easy.  Dealing with the junction between ROR and warm room roof is easier too.  No problem with matching panel sizes to the roof either.  Many years ago Tim and I constructed livestock sheds using timber framing and box profile roofing we bought at a local auction and basically we had to fit the timber to match the roofing panels.  These were pent roofs not apex.  Handling large roofing panels was difficult too, even with two of us.  Had to wait for a windless day!  Then it was a case of clambering up on the roof and hammering in dozens of roofing nails being careful to find the roof timbers!  My observatory roofing I did on my own although the EPDM was heavy.  Hence I conclude EPDM is much easier.