Gina's Observatory - The Build

[JamesF]

You know, I've managed to get through 45 years of life without knowing they were called "Brenton bolts" Learn something every day...

James

[Gina]

You know, I've managed to get through 45 years of life without knowing they were called "Brenton bolts" Learn something every day...

James

Yes, I've only recently found the name and I've managed nearly 70 years And been into DIY most of that time.

[Earl]

Gina I have some large wire tensioners left over from my build you can have them if you want?

These type

http://www.ebay.co.uk/itm/10-X-TURNBUCKLE-WIRE-STRAINER-TENSIONER-HOOK-EYE-M5-BZP-/260595148120?pt=UK_Hand_Tools_Equipment&hash=item3cacae6558

[Jessun]

Gina what a terrible storm that was for you! I'm glad nobody got hurt and that the obsy lives on. Designing for wind is probably tricky as it's hard to estimate the enormous forces involved.

Such a nice build too, and it looks like the roof section is intact? Good solid engineering there then!

All the best and hope you patch it up soon.

[Gina]

Gina I have some large wire tensioners left over from my build you can have them if you want?

These type

http://www.ebay.co.uk/itm/10-X-TURNBUCKLE-WIRE-STRAINER-TENSIONER-HOOK-EYE-M5-BZP-/260595148120?pt=UK_Hand_Tools_Equipment&hash=item3cacae6558

Thank you very much for your offer ATM I have another way of doing it if I can implement it, otherwise I'll get back to you

[Gina]

Gina what a terrible storm that was for you! I'm glad nobody got hurt and that the obsy lives on. Designing for wind is probably tricky as it's hard to estimate the enormous forces involved.

Such a nice build too, and it looks like the roof section is intact? Good solid engineering there then!

All the best and hope you patch it up soon.

Thank you very much

[Gina]

First I though of getting some mild steel rod to make the "spikes" but then thought aluminium rod would be easier to work. Not having a lathe I'll probably use an electric drill and file. I'm thinking of half inch (or 12mm) rod and just wanted to check with the engineering experts here that this would be adequate to hold the roof down. I was planning for it to engage with a similar size hole in 50x4mm aluminium bar and/or a deep hole in wood.

Advice would be welcome, Please

[JamesF]

Thinking about it Gina, it's rare for a wooden shed roof to be lifted off by the wind and they're often held on with no more than a handful of nails, so I don't think you need to go mad with this. I think the important thing is to make sure the anchoring points are firm.

James

[Freff]

Hi Gina. If you want anything turned on the lathe give me a nod.

As James said, it's the fixings that is important not the method. You could use security type hasp and staple, but using #10 screws to fix it will soon pull out.

In general wind conditions your roof will withstand gusts. It is when a sustained storm like the one we all experienced that will lift a roof.

I'm in an exposed position on the side of a mountain and we get a lot of wind whistling up the valley, so something substantial is needed.

I simply throw a few webbing straps (heavy duty) over the roof and anchor down.

In your case I would stick with the tried and tested methods, but have something ready for when we get severe weather warnings.

[Gina]

Thinking about it Gina, it's rare for a wooden shed roof to be lifted off by the wind and they're often held on with no more than a handful of nails, so I don't think you need to go mad with this. I think the important thing is to make sure the anchoring points are firm.

James

Thank you James I was flabbergasted when the roof lifted off - it's no lightweight! Mind you, we are on the SE side of a hill and the wind was in the east - it had a mile or more free run across the valley. OK I won't go mad

[Gina]

Hi Gina. If you want anything turned on the lathe give me a nod.

Thank you very much I'll bear that in mind

As James said, it's the fixings that is important not the method. You could use security type hasp and staple, but using #10 screws to fix it will soon pull out.

Yes, I understand that. I certainly intend to use solid fixings

In general wind conditions your roof will withstand gusts. It is when a sustained storm like the one we all experienced that will lift a roof.

I'm in an exposed position on the side of a mountain and we get a lot of wind whistling up the valley, so something substantial is needed.

I simply throw a few webbing straps (heavy duty) over the roof and anchor down.

In your case I would stick with the tried and tested methods, but have something ready for when we get severe weather warnings.

Thank you for your thoughts

[Gina]

Taking Tony's suggestion of using tried and tested methods, I have a pair of heavy duty hasps and staples as shown in the photos below. I think I can use these at the eastern end of the roll off wheel assemblies to fasten them to the main framework. This is shown in the diagram attached. Using them "upside down" compared with standard is necessary due to the width of the wheel framework. At least I think so, otherwise the hasp would drop down and prevent opening or closing the roof.

[JamesF]

I'd be tempted to use bigger screws I think. As long as you dare (I assume you don't want to go right through the wall, otherwise they could be replaced with bolts and plates) and a larger thread. Those ones look a bit weak and weedy.

Even if you don't want to go right through the wall, those should give you plenty of warning if they ever get close to failing so you have the opportunity to strap the roof down with a rope or two.

James

[Gina]

I'd be tempted to use bigger screws I think. As long as you dare (I assume you don't want to go right through the wall, otherwise they could be replaced with bolts and plates) and a larger thread. Those ones look a bit weak and weedy.

Even if you don't want to go right through the wall, those should give you plenty of warning if they ever get close to failing so you have the opportunity to strap the roof down with a rope or two.

James

I thought about bolting through the wall - I might do yet, with coach bolts - head on the outside. Those wood screws are 70mm long in 75mm thick timber and there are 4 or 5 of them. Maybe 4 no.10 and 1 nice fat coach bolt in the middle hole.

[Macavity]

That's pretty much exactly the system "Alexander's" (observatories) use too. One at each corner! I bought a more substantial matched quartet of padlocks. A bit of extra security too, but mostly I just leave the keys in and then you can undo them one-handed!

I do agree with the idea of #10/12 screws or greater and one M8-M10 coach-bolt through the centres of the hasp leaves / wall. On the "todo" list. Has survived one winter. I tend to keep an eye on the weather (roof level anemometer) - It gets pretty windy here at 200m asl. But I may add a pair of "emergency" turnbuckles in the middle, so if looks like getting really rough...

Either that, or like Quasimodo, I'll be in there swinging my ample weight from the rafters!

[yesyes]

Another vote for bigger screws/bolts. Ideally I would go all the way though the timber and use machine screws and nuts.

If the lift was able to lift up your whole heavy roof, these screws would probably not have stopped it.... And you may have had more damage on the obsy walls from pulled out screws...

[Gina]

I think I'll go for M10 coach bolts as in the rest of the build for the hasps but may have to go smaller for the staples. I think I may go "belt and braces" with "spikes" into holes for daily use and the hasps and staples when there's storms forecast.

[Bizibilder]

Gina - Have a look in my blog (for June 2010) and you can see how I made a set of four "pins" to hold my roof down (I used machine tools to make the bits but they can be made without quite easily) The roof fastens with a single conventional bolt which makes it easy for locking and unlocking. Hope this helps.

PS I'm glad to see you are unharmed, I've been following your misfortune and it sounds to have been quite frightening. I'm sure you'll get the obsy back together soon - you are a very resourceful young lady !

[Gina]

Gina - Have a look in my blog (for June 2010) and you can see how I made a set of four "pins" to hold my roof down (I used machine tools to make the bits but they can be made without quite easily) The roof fastens with a single conventional bolt which makes it easy for locking and unlocking. Hope this helps.

Yes it does - thank you That's a bit similar to how I thought of doing it apart from the angle brackets. What size are your pins? Looks like about half inch. I'm thinking of using 1/2 inch or maybe 3/8 inch but I think the former.

PS I'm glad to see you are unharmed, I've been following your misfortune and it sounds to have been quite frightening.

It was quite shocking - yes!!

I'm sure you'll get the obsy back together soon - you are a very resourceful young lady !

Shouldn't take too long once the roof is at - um - roof level "resourceful" - I hope so "young" - hardly "lady" I'll leave that up to others to comment on

[Bizibilder]

Sorry - should have said - the pins are indeed 1/2 inch and the angles started out as 3"x3"x5/16 (or whatever in metric). The system has survived a few gales with no problems at all.

[WakeyTiger]

Wow! Amazing to read this Gina, and a typically great response from all on SGL. Glad nobody hurt, it's so easy to underestimate the power of the wind in the UK...

Hope the obsy comes back bigger and stronger for it ;-)

Sent from my GT-I9100 using Tapatalk 2

[Freff]

Taking Tony's suggestion of using tried and tested methods, I have a pair of heavy duty hasps and staples as shown in the photos below. I think I can use these at the eastern end of the roll off wheel assemblies to fasten them to the main framework. This is shown in the diagram attached. Using them "upside down" compared with standard is necessary due to the width of the wheel framework. At least I think so, otherwise the hasp would drop down and prevent opening or closing the roof.

Just the job Gina. They will suffice for 99% of UK weather.

[Gina]

Sorry - should have said - the pins are indeed 1/2 inch and the angles started out as 3"x3"x5/16 (or whatever in metric). The system has survived a few gales with no problems at all.

Thanks

[Gina]

Wow! Amazing to read this Gina, and a typically great response from all on SGL. Glad nobody hurt, it's so easy to underestimate the power of the wind in the UK...

Hope the obsy comes back bigger and stronger for it ;-)

Sent from my GT-I9100 using Tapatalk 2

Thank you Welcome to SGL

[pete_l]

I've only just stumbled across this thread and your recent experiences,

Gina. Glad to hear nobody was hurt and that the damage was slight

(compared to what could have happened).

It got me thinking about the whole problem, though.

The "lift" caused by the wind seems to be caused by the smooth surface

of the roof which allows "laminar flow" of the air over it - just like on

aeroplane wings and tall chimneys. On planes, obviously it's

what they're designed for, but on chimneys it can be a disaster and

used to caused collapses.

To counter that, architects now add spiral "vortex shedders" to chimeys.

These will break up the smooth, laminar flow of the wind so that

its force is much reduced.

Maybe what we need to do with our roll-off obsy roofs is to add

"sticky-out" pieces to do the same: break up the flow of wind across

them to stop them acting like wings. It seems to me that a ridge

board, at the roof's apex could do this if it was tall enough (and

didn't get blown off) - and maybe one at each of the lower edges

of the slope, too - though these would have to let rainwater flow

off the roof and have a watertight connection to it.

I don't know how tall these would have to be to have the desired

effect - or even if it would work, but for the sake of a few pieces

of wood, it might help.

All we'd need then would be a hurricane or two to test the idea ...