Storm Damage

[Gina]

Is 163kg rating sufficient?  Negative pressure (lift) of 20pounds/square foot (i.e. 100kg/square meter) is easily generated by a strong gust.

Try out this calculator:  http://engexp.com/calculators/asce_comparison.cfm

Quick instructions:

Click on either the shed or house to give Risk category I or II then hit "Custom" where you can input roof type, slope and wind speed.  (To vary slope and wind speed click on the box and drag mouse up and down - you can't type a number)

The negative pressure (i.e. lift) is given on the second dial in pounds/square foot - calculated according to 2 sets of American building regulations 7-05 and 7-10

Changing zone allows the lift to be calculated at different parts of the roof (Zone 3 = Corner.  Zone 2 = Edge.  Zone 1 = The rest)

Hard data for hurricane-proofing your shed!

Mark

Thank you Mark - very useful

I'll check out the calculator shortly but meanwhile a rough calculation on my roof gives the following :-

• Size of roof about 2.5m square so area is 6.25 sq m
• @ 100Kg per sq m the lift would be 625Kg
• If this were evenly spread over the roof we would need 625/4 = 156.25Kg per corner

This would indicate that 163Kg per corner might just be enough but it wouldn't leave much margin.  I would rather adopt the Victorian engineers' code of allowing for twice the expected forces than the less safe modern ways.  So from that I would go for the 300Kg load rated fasteners.

[Gina]

Gina, sorry for your troubles but as saac has said your misfortune has made us all reconsider possible weather related security problems; you are as always a fleet leader!! albeit by default on this occasion. Onwards and upwards, hope the EQ8 survives.

regards

Mike

Thank you Mike   "fleet leader" - I like that

[Gina]

These trailer door locks look like they should be suitable but they don't quote the load rating.  May email the company and ask.

They are much bigger than the others we have been looking at and are made of 5mm steel.  Being designed for trailers with plenty of vibration when used on the road, they shouldn't have any problem with buffeting from the wind.  I have used similar door latches on cattle trailers and they're pretty hefty.  I think they should be quite adequate to hurrican-proof an observatory roof.

[Gina]

The latches I ordered - 318Kg 701 Lbs Holding Capacity Metal Latch Action Push Pull Toggle Clamp - have just been delivered by DPD and though rated at over 300Kg they look much lighter duty than those trailer door catches.  The frame is 2.6mm steel whereas the trailer door catches are quotes as 5mm.  I'll take and post a photo or two later.

I think I'll order one of the trailer door latches and seen what it's like.

[Gina]

Here's a photo of the 318Kg latch.  The carpentry rule is showing inches.

[Gina]

I've been out in the observatory and checked to see where this first latch will fit.  The eastern end has a problem - there is only about an inch gap between the fold down flap and the top bar of the obsy base on the SE corner and less on the NE corner.  This is not enough to clear the latch when opening/closing the flap (opens inwards)   There is a 12mm pin and hole roof locking system when the roof is closed though.  A 12mm aluminium pin in a hole in the corner post (75mm square) and matching hole in the roof frame.  At the warm room end (west) the fitting is a 12mm gate latch pin fitted in a hole in the main roof cross beam and a 10mm welded eye bolt fitted into the framework of the dividing wall.

I think the answer for my roof may be to have pin and hole or pin and eye bolt roof anti-lift at each corner and have the trailer door latches at the mid point - aligning with the apex of the roof where there are main roof supports.  There are substantial timbers on the four corners and in the middle supporting the apex beam and top framework.  The mid-point latches will add further and substantial fastening against lift and also prevent the roof rolling back.  I'm thinking of using the trailer door latches.

[happy-kat]

Have you put deflector shapes on the roof ridge?

Like what came up when lift was discussed months earlier and how the Victorians and their fancy ridge tiles had a purpose.

[Gina]

Have you put deflector shapes on the roof ridge?

Like what came up when lift was discussed months earlier and how the Victorians and their fancy ridge tiles had a purpose.

No, not as yet.  I shall need decent weather to do it as I shall need a ladder to get up on the roof and at present it would just disappear down into the mud!

I might be able to put something along the eastern edge just above the guttering as I can get to that with the roof open with a pair of steps in the scope room.

[Davey-T]

I can see a complete roof design project coming, something based on the inverted aerofoil model.  

Dave 

[Macavity]

Sorry to hear of your chagrins, Gina.

I found that, depending on calculation method and guestimated weights, my roof

is either perfectly safe or should have disappeared into the next parish ages ago! 

But, at 200m up on a (very windy!) Welsh hill, I often worry...

Already have hasps / padlocks at each corner. Intend to add four turnbuckles in

the mid-section. But frankly, I sense there is little obstacle to screws tearing out

or the attachment timber points simply splintering. Still thinking about that one...

The roof is very heavy, but I didn't build it, so not sure what's attached to what!

The most disappointing aspects is, but a few years on, the roofing felt has badly

*scoured* - Now looks like planet Mercury! But perhaps suggsting the airflow is

more turbulent than laminar! I assume the roofing felt was just very cheap stuff...

I saw somewhere that certain dicky birds might be partial to a little nibble too! 

Or maybe: http://pdfpiw.uspto.gov/.piw?docid=05918423&SectionNum=1&IDKey=C0A3EC025958&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1%2526Sect2=HITOFF%2526d=PALL%2526p=1%2526u=%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r=1%2526f=G%2526l=50%2526s1=5918423.PN.%2526OS=PN/5918423%2526RS=PN/5918423 (An ever intriguing idea!)

[Gina]

-

[Gina]

Sorry to hear of your chagrins, Gina.

I found that, depending on calculation method and guestimated weights, my roof

is either perfectly safe or should have disappeared into the next parish ages ago! 

But, at 200m up on a (very windy!) Welsh hill, I often worry...

Already have hasps / padlocks at each corner. Intend to add four turnbuckles in

the mid-section. But frankly, I sense there is little obstacle to screws tearing out

or the attachment timber points simply splintering. Still thinking about that one...

The roof is very heavy, but I didn't build it, so not sure what's attached to what!

The most disappointing aspects is, but a few years on, the roofing felt has badly

*scoured* - Now looks like planet Mercury! But perhaps suggsting the airflow is

more turbulent than laminar! I assume the roofing felt was just very cheap stuff...

I saw somewhere that certain dicky birds might be partial to a little nibble too! 

Or maybe: http://pdfpiw.uspto.gov/.piw?docid=05918423&SectionNum=1&IDKey=C0A3EC025958&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1%2526Sect2=HITOFF%2526d=PALL%2526p=1%2526u=%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r=1%2526f=G%2526l=50%2526s1=5918423.PN.%2526OS=PN/5918423%2526RS=PN/5918423 (An ever intriguing idea!)

Thank you Chris   I'm 200m up on the side of a very windy English hill   Very open from NE right round to SW.  Both times the roof has shifted the wind was in the SE - the very worst direction for wind lift would be 15 degrees south of east.

Those ridge cap spoilers look very interesting - should certainly break up the laminar flow.  My roof has rubber roofing and is very smooth with a very smooth bend over the ridge - an excellent aerofoil for winds in the east!

I guess a length of timber going from an upright piece one side to an upright piece the other side would do the trick.  I'll have to see what I've got left.  About 2.5m long.  I don't want to puncture the rubber roofing by screwing through it.

Regarding fasteners to hold the roof down...  How these are attached to the timber roof and base members is something I'm very concerned about.  Attaching them with the ubiquitous "inch 8" screws would simply not do!  All parts of the framework are bolted together with substantial coach bolts and these fasteners need bolting on too.

[Gina]

The scope room and EQ8 are looking dry now and the RH of the air is down to about 40%    I shall probably leave the mount for a few days more before trying power on it.  Now the floor is dry I can put the flooring back down.  Not today though - I've finished outside for today having recovered the goats again from up the road and sorted out the roadside fence   Unles I get a new supply of energy later on

[saac]

Gina, those trailer latches are more like it, I'm going to give them a try.  I reckon I would need at least 4 for my summerhouse conversion but I can't afford that at the moment .  I've just about blown my monthly allowance on wood to finish off my roof.    I hate to think what I've spent on this now.   I notice from the ebay page it allows you to pick them up from Argos, that's quite handy - never noticed that before.  If you do get anything back from the manufacturer re loading characteristics I'd be grateful if you could posts it.  Thanks again for sharing the link.

Jim

[Gina]

Gina, those trailer latches are more like it, I'm going to give them a try.  I reckon I would need at least 4 for my summerhouse conversion but I can't afford that at the moment .  I've just about blown my monthly allowance on wood to finish off my roof.    I hate to think what I've spent on this now.   I notice from the ebay page it allows you to pick them up from Argos, that's quite handy - never noticed that before.  If you do get anything back from the manufacturer re loading characteristics I'd be grateful if you could posts it.  Thanks again for sharing the link.

Jim

Yes, they look good to me   As I said above (I think) I have ordered one to see what it's like and if OK as I expect I'll order another.  "Estimated delivery Wed, 19 Nov - Thu, 20 Nov".  I will certainly pass on any info I get

[Gina]

I've put the EQ8 back together and gradually applied power.  All well   Had current limit initially set to 3A and raised volts to 13.8 and then back down to 13.5v.  Connected laptop and ran CdC.  Tried connecting and then slewing - AOK   Tried parking and the current limit of 3A was exceeded (to be ecpected) so I put it up to 5A (the value of the inline fuse) and tried again.  This time it was fine   Tried parking to the several park positions I have set up and it appeared to go to the right place    Next I put all the covers back on and checked it again.  I can't check the accuracy of the goto as I have no scope on the mount but it looks fine

Conclusion - The EQ8 is fine - it has survived its drenching

[Davey-T]

Jolly good       

Dave

[Dave Lloyd]

How do you get on with insurance Gina. I understand that big bought items can be covered but what about all the (wo)man hours and ingenuity that goes into all those amazing projects. They're one offs that it must be hard to put a value on other than basic parts costs.

[Gina]

How do you get on with insurance Gina. I understand that big bought items can be covered but what about all the (wo)man hours and ingenuity that goes into all those amazing projects. They're one offs that it must be hard to put a value on other than basic parts costs.

I don't really know.  Yes, the hours of work put in is a point but I doubt I could get compensation for that.  I don't think I would even bother to try - it would be impossible to assess.

I have been lucky in having no real damage   And on a positive note, it's got me looking into improving my storm security   And, I think, has been a warning to others so may help to prevent damage to other people's buildings and equipment

I'm hoping the heavy duty toggle latch will come tomorrow, meanwhile the roof is firmly fastened by a large G clamp and pins in holes.  I should have the full saftey measures ready before the next storm - no forecast of storms in the next 10 days.

[Zakalwe]

It'd be worth opening the panel on the EQ8 and giving the motherboard and the insides a good blast of WD40. That'd help to disperse any remaining moisture that might cause electrical connectors to fur up and rot over time. I've owned Suzuki motorbikes in the past and that was considered essential maintenance on their rubbish connector blocks.

[jarl72]

Just a quick note: I saw a couple of images where there are straps used vertically (straight down from each corner of the roof). Back when I had to carry a kayak on top of my car, people suggest to set the straps at an angle, though. Wen placed vertically there can be a large movement before the strap starts to counteract the movement (the straps would prevent the roof to move straight up, but that's unlikely to happen anyway).

This would apply for latches as well, I guess... I would put them at opposite angles on each side so the roof is under some tension to begin with.

Cheers!

[Gina]

My neighbour told me the rubber roofing on the eastern end of the roof had come loose and was lifting up so I'm just back in from fixing it.  Took a length of timber about 2m long and 28mm x 22mm and nailed it onto the roof to hold the rubber down.  Bit shorter than the width of the roof so room for the rainwater to escape at the ends - I put it on top of the roof as the rubber had already torn a bit on the edge of the roof.  Didn't really want to put it on top as water will stay in the corner between wood and rubber but it might help to disturb the aerofoil shape   I might replace it with something better when the weather gets warmer (in the spring probably).

Quite a strong SE wind out there and felt very cold - now I'm gradually thawing out

[Gina]

Something like this lino ridge strip in 2700mm length perhaps.

Or several of these

Rubber4Roofs have Sure Edge Gutter Drip Trim but with a small tear on the top of the roof will not be suitable.  See this page as the previous link isn't working.

[Gina]

The trailer door toggle latch has arrived and it's huge   No doubt whatsoever that a couple of these will hold the roof on in a hurrican.  In fact the latch would hold when the force was enough to break the roof up I should think!  It's literally twice as big as the other one I've got (318Kg rated load) so it should take four times the load - that's well over a tonne   I've ordered a second one and will put one on each side near the middle of the roof and bolted right through the carriage rails and upright to the apex.  They take 8mm bolts   The lower part (tioggle) will be bolted to the main framework, to an upright and the top rail.

[Gina]

Here's the two latches together.