# Sprung, Trapped Floor System



## AlexDonkle (Dec 9, 2014)

Most stage floors I've come across are designed for use on flat, concrete floors. Is it even possible to have a sprung floor that has removeable traps? The only pre-fab trap system I've seen is Staging Concepts traps but these seems to be designed for a non-sprung stage floor.


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## BillConnerFASTC (Dec 10, 2014)

I think its possible but not perfect or inexpensive. Some years ago i designed traps - steel frame, ply, and stripwood - in a sprung stage and set them on rubber pads - like 6x6 pads with steel plates top and bottom. It was better than not sprung.

Today I think I would do similar, but trap would be solid wood, and might put pads at corners and midpoints without the steel frame.


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## AlexDonkle (Dec 10, 2014)

Interesting, any idea why it's not a more commonly needed system for a manufacturer to pre-fab a solution? I'd think most trapped stage floors see some type of dance eventually, even just dance numbers in a musical.


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## BillConnerFASTC (Dec 10, 2014)

Honestly, I've never thought of traps as other than dead custom, and design and detail the whole thing, working closely with architect and structural engineer to get details right. Perhaps it is because I detest a maze of support structure and prefer to get by with minimal columns with no cross bracing. Hard to do with standard platforms from Steel deck, Stageright, Wenger, Stageing Concepts, SECOA, etc. Actually SECOA is custom building a system for me now - but not like one they have ever built before - all dead custom and one of a kind.

(Pit fillers, on the other hand, I do use some standard designs of platforms, usually with custom supports or some one of a kind structural framing under that is special.)


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## MNicolai (Dec 10, 2014)

AlexDonkle said:


> Interesting, any idea why it's not a more commonly needed system for a manufacturer to pre-fab a solution? I'd think most trapped stage floors see some type of dance eventually, even just dance numbers in a musical.



Trapped floors and other non-sprung floors still see dance. Just that the groups that it really matters to will tour with their own sprung floor in addition to their own dance floor surface.


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## DuckJordan (Dec 10, 2014)

I work in a venue that has a permanent sprung floor... we also have 6 traps. (they were used once when the building opened, since then they haven't been touched.) as a road house it was probably the most useless thing they put in the space. (other than the dock that raises at a 15% grade so all the cases want to enter the building of their own accord). That said the construction is simple. Steel beams surrounding the edges. A steel cross piece located dead center (ours our 4'x4' traps.) The center cross piece is removable which opens the trap door completely. On top of that sits a rubber "grommet" for lack of a better word. On that sits our on edge pine deck.


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## firewater88 (Jan 6, 2015)

I have a full sprung stage floor with traps. 6 of them to be exact, roughly 4' x 6' each. A royal PITA if you ask me. Never been used, wanted to, but have to much other work to do to make work. Basically they put down a double ply base on top of 2x12 stringers on 8" centers with a laminated beam down the center and then built the sprung floor on top of that. So when I pull up a trap section from above, all I see is plywood. all the trap pieces are all wood stuffed with insulation and have the rubber pads in the corners and mid way down long side. 
For small dance groups, marley on top is OK, although you can see the traps underneath the marley. The larger groups bring their own floor and marley. Otherwise, I have to tape the seams to keep the day to day crap out of the trap hole. I need to figure a way to latch them to the rest of the floor, maybe coffin lock or something. Kinda wish they just were not there...


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## BillConnerFASTC (Jan 6, 2015)

Classic latch for traps are turnbuckles - eye on trap and a hook to grab support flange. I'm using over center latcheson a system now - like these: http://www.protex.com/TLH-SHAB-037-...n-mild-steel-zinc-plate-passivate-silver-blue


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## AlexDonkle (Jan 7, 2015)

BillConnerASTC said:


> Classic latch for traps are turnbuckles - eye on trap and a hook to grab support flange. I'm using over center latches on a system now - like these: http://www.protex.com/TLH-SHAB-037-...n-mild-steel-zinc-plate-passivate-silver-blue



Kind of surprising the weight of each trap doesn't hold them in place. Latches bolted to the underside of the support steel around each trap would be fast to tighten / remove though. Short dowel rods drilled into each trap and lined up with holes in the support steel might also work pretty well to keep them from shifting around.


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## BillConnerFASTC (Jan 7, 2015)

Traps invetitably bounce or rock a little, especially under actors or dancers, and need holding down. The turnbuckles - and hopefully my latches - are very tolerant to misalignment. I wouldn't worry much about shifting laterally - they are fairly locked in position.


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