Show me your Grid

[Eeen]

Evening,

 

Just wondered if anybody has installed a grid ? im after help with photos so I can design and work out whats needed. whats the spacing of your slats? and the size?

 

My theatre has an under slung grid (hoist pullys mounted on the celing) and thus making servicing/testing etc a pain and we have 10 dead hung bars and 10 on hoists.

 

I would like to install a wooden grid to run on top of I-beams that run down stage, mid stage and up stage, from SL to SR. It would be approx 1m above the height of the limit of the bars and with about 1.5m to the celing.

 

Im thinking of using 3x1 Timber with about a 2" gap between.

 

Looking forward to your thoughts

 

Thanks

Ian

 

 

 

*Mod's feel free to move if in wrong area*

 

 

[brainwave-generator]

Evening,

 

Just wondered if anybody has installed a grid ? im after help with photos so I can design and work out whats needed. whats the spacing of your slats? and the size?

 

My theatre has an under slung grid (hoist pullys mounted on the celing) and thus making servicing/testing etc a pain and we have 10 dead hung bars and 10 on hoists.

 

I would like to install a wooden grid to run on top of I-beams that run down stage, mid stage and up stage, from SL to SR. It would be approx 1m above the height of the limit of the bars and with about 1.5m to the celing.

 

Im thinking of using 3x1 Timber with about a 2" gap between.

 

Looking forward to your thoughts

 

Thanks

Ian

 

 

 

*Mod's feel free to move if in wrong area*

 

 

 

Sorry what is the purpose of this grid? Access? The only reason I ask is that some grids, whilst permitting easier access of the blocks, are also used for hanging either static loads, or for installing motorised rigging points if you have concerts etc in. The suitability of the grid for this is usually deemed by the building's structural engineer.

 

If it is just access will catwalks not do rather than a full grid? Unfortunately there might be some complications with just chucking up a timber grid, since access has to conform to certain specifications now. I have recently gone through this drama with another venue which installed wooden catwalks as a convenience to the riggers to save us jumping from beam to beam, but have actually been told from the councils point of view they are actually worse, since the handrails are not up to spec and we might fall through them. WE WALK ON BEAMS AND YOU SAY THAT'S OK... BUT YOU'RE WORRIED ABOUT US FALLING THROUGH HANDRAILS? So yeah, just warning you, it might be a can of worms. If it's not there to hang rigging from, and only there for access; it may have to conform to certain access requirements and then that would obviously dicate your choice of materials and design.

 

Depending on your budget, catwalk truss might be an option, hung from the building's structure. It's not cheap but you do occasionally see the older Slick stuff crop up on Gearsource. That's what we did with the above place, there's now a lovely 12m centre catwalk in there. Another benefit of catwalk trusses is that, providing what they're hung from is suitably rated, you can use them to hang rigging from.

 

In your situation with the I-Beams already there, I would be inclined to use further I-beams rather than timber. Run them up-down stage but much closer together. You could use small I-beams if the weight is not going to be anything too much. Lindapter make nice little things for joining I-Beam to I-Beam even if they are different sizes. These clamps are good and not too expensive.

[ramdram]

Shirley this a "Stop" moment?

 

It may be that you need all sorts of planning permissions, consents, building regs, etc, etc. Suggest you find out from local authorities what you HAVE to do first...as in what they want in the way of materials, designs and drawings. It may be timber is out because of fire regs, say?

 

And unless you are qualified (we love this word on BR) and know how to produce "proper drawings" then be prepared to part with some cash.

[kerry davies]

Hi, your profile states that you work in a relatively new-build school theatre which is where the STOP NOW comes into play.

 

If it is a private school this is something you need to first discuss with the bursar to identify with the architects whether or not you can do anything and what that might be.

 

If it is an LEA school then the head should contact whoever is the buildings manager at the LEA to set things moving.

 

If it is a Free School, then do carry on, half of them aren't insured anyway!

[J Pearce]

Kerry, don't forget the new category of Academy. We don't report to the LEA, but I'd like to think we are a touch more organised and professional than some of the free schools I've seen.

The concept is we run in a similar self governed fashion to private schools, but with government money.

 

To the OP, I can't see how building a grid is cheaper than hiring a scissor lift for the yearly maintenance?

[brainwave-generator]

Shirley this a "Stop" moment?

 

It may be that you need all sorts of planning permissions, consents, building regs, etc, etc. Suggest you find out from local authorities what you HAVE to do first...as in what they want in the way of materials, designs and drawings. It may be timber is out because of fire regs, say?

 

And unless you are qualified (we love this word on BR) and know how to produce "proper drawings" then be prepared to part with some cash.

 

It depends really doesn't it.

 

If you put a truss across 2 RSJs to hang a point in between, it's a 'spreader beam' and that doesn't need planning permission, it's a fairly normal rigging operation.

 

Why does this change when you use a third RSJ instead of truss? The fixtures could still be classed as 'temporary' so it could still come under temporary rigging which doesn't need any planning permission or anything like that.

 

This is what my post was aimed at. If you install it as an access area, then yes there is legislation and steps to go through before installing it. If you install it as part of the rigging system, to make installing points off the existing RSJs easier, then it doesn't. They're just spreader beams and you can install them as you wish. If people then decide to walk on them to access the blocks that is their choice.

[ramdram]

** laughs out loud **. There must be countless posts on the SWL and WWL, so to speak, of existing RSJs and similar. Even if you do use it's "only the spreader beam" ploy then you would still to know what the beams could support.

 

However, the OP writes of "designing" which is a tad more to just using a spreader beam. Ergo "we" could not really endorse just carrying on with the project willy nilly. And especially to say it is a person's choice to stroll around an unrated structure is not perhaps the most sensible advice.

 

In another thread we have gone on at length about what "qualified" riggers can or cannot do, yet now we are suggesting it "all depends" so that the OP may be under the impression that by using semantics he might safely cobble up a structure on a platform which may or may not be suitable.

 

There are many youngsters who read this forum and if the best we can do is to imply "it all depends" is not reinforcing "the safety first ethic"...or "if you have to ask on a forum" diktat is not really giving proper guidance to the unqualified yet keen as keen nipper.

 

When it comes to "building or hanging or flying" stuff, or cobbling in power supplies say then the very best advice is consult the professionals first, second and third.

[Eeen]

Firstly, Thanks for all your comments.. I am taking them all on board....

 

I have sold the idea to the bursar as an access feature with the potential of using it for rigging points. on the other hand I have sold it to the Head of Drama as Rigging rather than access.

 

And for me (most importantly) rigging and then access, as the theatre is beeing used by more and more external events. (+ it would gain me a further 1.5m flying height!

 

I know that the school architect is in and out at the moment with a couple of projects we are starting in the summer. so I will collar him too, come to think of it I think I have the structural engineers email some where too...

 

Catwalk truss sounds like an option, I'll look in to it, Thanks.

 

I have been in long discussions about a sissor lift and last year on our re-test the company hired a scaff tower to build up and through the flying bars and it was a major pain in the backside to gain access. Unfournataly the theatre is on the 1st floor and we have hired a scissor lift but for the height It wont fit in the buildings lift ! plus I then loose inastant access to the rig and would have to wait for a tower etc... as we squeeze many many productions in to the year, and lets face it instant access with a permanent structure everytime over a tower build.

 

Please continue with any comments.

 

Thanks

Ian

[brainwave-generator]

** laughs out loud **. There must be countless posts on the SWL and WWL, so to speak, of existing RSJs and similar. Even if you do use it's "only the spreader beam" ploy then you would still to know what the beams could support.

 

However, the OP writes of "designing" which is a tad more to just using a spreader beam. Ergo "we" could not really endorse just carrying on with the project willy nilly. And especially to say it is a person's choice to stroll around an unrated structure is not perhaps the most sensible advice.

 

 

This 'rating' thing on Blue Room is all got very wrong every single time. Just because an item does not come with a piece of paper or a stamp saying what it's good for, it doesn't mean you can't hang things on it. That's an urban myth. A structural engineer can rate beams in a building and advise you on what you can suitably hang from them. I-Beams are a lot cheaper than truss so if you can use them for the purpose in hand there is nothing wrong with that.

 

At no point did I suggest you can just throw an I-Beam in a roof and start using it without checking. Yes, I didn't explicitly suggest you should, but neither did I explicitly suggest that you should not set yourself on fire with a blowtorch and a can of camping gas.

 

In another thread we have gone on at length about what "qualified" riggers can or cannot do, yet now we are suggesting it "all depends" so that the OP may be under the impression that by using semantics he might safely cobble up a structure on a platform which may or may not be suitable.

 

There are many youngsters who read this forum and if the best we can do is to imply "it all depends" is not reinforcing "the safety first ethic"...or "if you have to ask on a forum" diktat is not really giving proper guidance to the unqualified yet keen as keen nipper.

 

When it comes to "building or hanging or flying" stuff, or cobbling in power supplies say then the very best advice is consult the professionals first, second and third.

 

They key with every.single.thing we do in ANY part of the industry with any risk to safety is that it is done by competent people. That's just a given. Whether they're truss or RSJs or a scissor lift... it needs to be done by a competent person. That is - the installation, having them rated for use, and using them.

 

Just because I suggest a design idea, it does not by any stretch of the imagination suggest that the OP buys himself a couple of ibeams, hangs them up using duck tape, and starts hanging double decker buses from them. It is common sense that the design, installation, rating and use is done by competent people; but this does not mean you can't put the options over the table, just so the OP can have a think about what's available and what it's going to cost.

[paulears]

If you do your own testing (as in original post) then you presumably have somebody with the engineering background on staff. Very few venues do their own testing of the structure and machinery fitted. Our very cash strapped venue would love to be able to do this, as the annual inspection is a ongoing cost that has to be met from very limited funds, but none of us are able to (or want to) take on the job - because frankly, we're not up to it. I can think of plenty of engineering firms who could construct what you want, but I suspect they'd use metal rather than timber. In construction it's quite common to use temporary bridges, with handrails - to span gaps between beams. We have one in our roof void to allow access to an area not connected by the original installation timber walkways. It's aluminium - similar to a loading ramp, with side rails, and quite light. This kind of structure would be what I'd imagine most engineering companies would use in your circumstance.

 

I can recommend the company we use - they are very familiar with schools and would be able to design and construct what you need. I note you then mentioned later using the new floor for rigging points. This is completely different, and a work platform and a structure capable of being suitable for rigging from would be very different, and no doubt very much more expensive.\

 

If you want the phone number and contact details - just drop me a note and I'll pass on their number. From the certification and fabrication point of view, they'd find little problem in the job - but you are talking a lot of money - and unless the venue is an income source, hiring in something for the annual test and maintenance would be much, much cheaper.

[david.elsbury]

I'm really confused. The OP wants to use 3x1 timber. To hang things off? This seems grossly inadequate for this. Also what's the point of installing it 1m above the 'out ' dead of the existing bars? You won't be easily able to work on or inspect them...

 

And I agree, I'd be starting with the structural engineer.

 

Brainwave, the danger with putting the options on the table as it were are that if someone inexperienced or incompetent reads your /our advice and puts it into practice and does it badly and creates a situation where someone gets injured or killed ... well..

[Brian]

I'm really confused. The OP wants to use 3x1 timber. To hang things off? This seems grossly inadequate for this. Also what's the point of installing it 1m above the 'out ' dead of the existing bars? You won't be easily able to work on or inspect them...

 

You're not the only one.

 

As I read it the OP wants to build a timber theatre-style grid which will end up 1m below the structural ceiling to...

 

a) make access to the pulleys fixed to the ceiling easier

b) give them somewhere to hang temporary loads from

 

The plan fails on so many levels...

 

a) 1m is nowhere near enough headroom for a working space

b) 3x1 timber is not suitable for structural use

c) a timber grid is a real fire hazard

[gyro_gearloose]

b) 3x1 timber is not suitable for structural use

It is if its sitting on 8x2 joists spaced about a foot apart, like our grid is. Our venue was originally a hemp house so the original grid was made entirely from timber. A steel fly tower was installed in the eighties to support our counterweight system, so the old wooden grid is now used for access to other areas of venues internal roof-space. However, as others have already said, a new-build grid should be made from steel and the OP should not be designing it himself.

[ramdram]

BG the problem is that your posts can be misleading to the inexperienced nippers who have no idea on how to read the post, and read them they do.

 

The OP appears to have access to sound advice and says he will "ask a man who does/can/will", which is sensible in that he has passed "ownership" of the project to someone else...who can make these things happen, or not of course.

 

What you are perhaps forgetting is that not everyone who reads BR has the background to understand "your point". For example, it could be that in some places the steel work in itself is rated for many tons, yet the masonry on which it rests or into which it is integrated may not.

 

(After all, masonry structures can "move" and it is for that reason the mortgage folk strongly suggest you engage a surveyor to perform a full structural survey before you sign on the dotted line.

 

They have learned, from vast experience, that buildings don't always withstand the tests of time, or rigours of even "normal" ground movement.)

 

And, whilst your idea of spreader beams and the like sounds reasonable (and is reasonable) your suggestion that folk strolling around on homebrew structures "is their choice", is not.

[brainwave-generator]

Brainwave, the danger with putting the options on the table as it were are that if someone inexperienced or incompetent reads your /our advice and puts it into practice and does it badly and creates a situation where someone gets injured or killed ... well..

 

 

That is bull. Sorry, but it is. You don't not post something because somebody might take it and do it badly. People could just buy a book and do it badly from that.

 

 

So whilst your idea of spreader beams and the like sounds reasonable (and is reasonable) your suggestion that "folk strolling around on homebrew structures is their choice", is not.

 

So it's alright to hang a one ton point on something but not to walk on it?

 

How much do you weigh?

 

It's aluminium - similar to a loading ramp, with side rails, and quite light. This kind of structure would be what I'd imagine most engineering companies would use in your circumstance.

 

 

They're actually often made by truck ramp companies.

 

http://www.theramppeople.co.uk/walkways-and-gangways