# New Stage Structure



## kicknargel (Feb 11, 2010)

So one of the dinner theatres I work with is renovating an old movie theatre into a new space. The upstage half of the stage will be built up about 3' from the existing floor. They are digging a pit under the downstage half of the stage. The contractor specified running I-beam girders up/down stage, then running joists on top of those running cross stage, and plywood, etc on top of that. 

I'm pushing for a more modular solution. I'd think maybe upstage the stage could be individual 4x8 platforms. And maybe over the pit there could be platforms framed thick enough to span the girders.

I'd like to be able to remove a section and put in a plug with a trap door, revolve, etc.

So what is the setup in your theatre, especially if you have a modular system, and double especially if you have a trap room/pit. I think I've seen some that had girders with smaller I-beams that ran in between them, but were removable.


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## Footer (Feb 11, 2010)

It takes a bit more then a 4x8 platform to form the stage proper. Most places that I have worked/been in that are "trappable" only have one area of the stage that is dedicated to the trap. Usually its downstage centerish. Some places have a 10x10 trap and others are just a 4x8 plug. 

Usually, the trap is filled in by some type of beam that runs on 2' or 4' centers US/DS or SL/SR and then has a series of decks that go on that. On top of the decks is usually the sprung floor material followed by maso etc. 

Most places that have a trappable deck can only access it by pulling up a good amount of flooring. The places that do have "plugs" that you can easily pull usually have some kind of issue with them. 

Its a balancing act between having a trappable stage and having a stage that appears seamless. It is also a balancing act between how easy it is to pull the trap and how seamless the stage looks. 

I have worked in plenty of venues that have trappable stages that have never pulled them. If you foresee yourself producing the types of shows that need a trap, its not a bad thing to include. However, keep in mind there is usually a lot of work and money that has to take place under the stage when a plug is pulled. It usually involves scaffold towers and all kinds of bracing. When you pull out just one beam to do a 4x4 hole, you then have to completely redesign how you are going to brace the rest of the floor around the hole. You also have to deal with lifts and all that fun stuff. If you foresee budgets being large enough to be able to deal with it, push for it. Otherwise, you might want to look into how you could use your orchestra pit as a trap or some other option like that.


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## ajb (Feb 11, 2010)

I know of one place where the pit is basically from 10' US of the proscenium to 10' DS. It's covered by 2'x10' platforms made from something like 10x2x14ga steel channel skinned with two layers of 3/4" ply plus maso, with four threaded inserts near the corners so that eye bolts can be screwed in for lifting with a chain hoist. They run US-DS, so the 10' of depth US and DS of the proscenium can be pulled in 2' wide increments. The plugs are only supported at the ends, so there's plenty of clear space below. Seems to work pretty well for them overall. 

If you have your construction contractor build the system, though, be sure to specify tolerances in writing. The major drawback to the system I described above is that the the plug sections are built sloppily and the pit opening is about a 1/2" smaller than it should be, so it's a big pain in the neck to get everything to fit how it should.


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## derekleffew (Feb 11, 2010)

A college theatre I worked at had a trap system based on 4'x6' modules, with girders and joists that could be removed to make various rectangular openings. I think of around 30 shows, one used one trap. Plus the traproom had like a 12' "ceiling", no idea why. Not worth the expense/trouble if you ask me. Orchestra pit fillers is a whole 'nother thang, though.


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## Footer (Feb 11, 2010)

derekleffew said:


> Plus the traproom had like a 12' "ceiling", no idea why. Not worth the expense/trouble if you ask me.



At my "summer home" the trap room for both theatres ceiling is at 20ish feet, hence the reason the trap has not been pulled since the 70's.


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## Sony (Feb 12, 2010)

One place I work has a pretty interesting trap system in their larger of the two theatres. Basically the stage floor is made of 4x8 platforms and is supported by Schedule 80 steel pipes on adjustable stands at the 4 corners of each platform. Each pipe is centered and holds up the corner of 4 platforms. Basically when they want a trap they can just unscrew one of these 4x8 platforms and they have an instant hole in the floor. The trap room ceiling is 10ft and they have a lift that they can move and position under any part of the stage, it's pretty nice. The trap room is literally a forest of vertical Schedule 80 1.5" pipes. It makes a very smooth stage and is infinitely flexible.


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## Morpheus (Feb 12, 2010)

At my school's main theatre, we've got 3 zones DS that we can open up, if needed... the CS zone is 2x larger than the zones either side, due to how they built it, and are supporting it... the ceiling is roughly 20', but our orchestra lift is on hydraulics, so it goes from stage level to trap room floor.

We've also got a paint track against the US wall, if someone was so inclined as to paint a backdrop.


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## museav (Feb 12, 2010)

I think your Architect may have to address any potential implications. For example, would such construction be considered permanent or temporary? Could it potentially affect any fire separation? Might it make an inaccessible or unoccupied area considered accessible or potentially occupied? Could it require the floor slabs below to be altered in order to potentially support lifts, turntables, etc. at any location?

I'm also wondering, with a totally modular floor system how do you deal with stage boxes or is everything limited to connectivity at the walls?


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