# Questions on a typical sprung floor in a working theatre.



## gafflover87 (Apr 9, 2012)

First, I know there are many threads on this, but none of them seem to answer my question. So the powers at be have requested that I look into replacing our current stage floor (concrete-> ply-> masonite) with a sprung floor. We are first and foremost a theatre, but we are looking to add dance to our repertoire, so a sprung stage is naturally one of our first steps. The floor needs to be able to support a set and our scissor lift, so it needs to be sturdy. So a few questions.

1. Rosco's Sub-floor cannot support the weight of the genie, is it acceptable to put layers of ply on top of he sub-floor?
2. Rosco's Sub-floor is quite pricey, one cheaper option is to build a basket-weave like Harlequin uses, how many additional layers of ply would you recommend going above the basket-weave?
3. To top it off, Im naturally drawn to using masonite, but I am open to using t&g hardwood. Would it be acceptable to skip this layer and put a permanent layer of another Dance floor like Roscoleum, which is said to be very durable and suitable for theatre scenery? Or is there a different material all together?
4. Any other thought, questions, or concerns?

I would like to save as much money as possible... however money is potentially not an issue when it comes to a durable, top quality floor.


Thanks guys.


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## Van (Apr 9, 2012)

I can tell you our sprung floor is 1 layer of 3/4" ply ontop of the cement, then a layer of 1x4 sleepers laid in at 45 degrees then 2 layers of 3/4 at right angles to each other. We then apply whatever flooring< masonite / MDF> over the top of that. The sleepers are left loose the top two layers of PLy are screwed together.


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## venuetech (Apr 9, 2012)

I have a concrete subfloor with 3.5" x 3/8" square rubber pads, on top of the pads are 2x4 sleepers (laid flat) on 24" centers, 3/4" tung and groove ply with 3/4" particle board top layer.
The original floor had MDF 7ply on top but the heavy caster load of the acoustical shell and other items would quickly delaminate the plywood.


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## marmer (Apr 9, 2012)

venuetech said:


> I have a concrete subfloor with 3.5" x 3/8" square rubber pads, on top of the pads are 2x4 sleepers (laid flat) on 24" centers, 3/4" tung and groove ply with 3/4" particle board top layer.
> The original floor had MDF 7ply on top but the heavy caster load of the acoustical shell and other items would quickly delaminate the plywood.



Our floors are very similar to this with either tongue and groove flooring, masonite, or carpet as the top layer depending on the application. It's a good solution for structure-borne noise and it does feel good to the feet. Yes, sometimes the plywood does delaminate; sometimes we replace it, often we just screw it back together with short screws. Also, over time (10 years+) the rubber pads can squish and need to be replaced.


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## stevek (Apr 18, 2012)

Hello gafflover87. I’m new to CB and I’m in the sprung floor business. It is possible to create a floor that would be supportive of a set and still provide the dancers/performers with the benefits of a sprung floor. If the set design were to change often with heavy sections or pieces it might mean a specific layout for each, so that the set was supported properly but it can be designed and implemented. The floor would be designed to be “sprung” where the performers are for the given performances and the set elements would be supported to the substrate. For different scenery layouts the support points would be changed. For the scissor lift, spreading the load as much as possible would be the best option, which would limit the degradation to the closed cell foam support layer and the potential for problems with rupture of the cells which cause uneven responsiveness of the floor. Successive flooring layers on top of the sprung floor, would decrease the “sprung” aspect of the floor as more structure would decrease the vertical absorptive ability of the floor as dancers land from leaps jumps, etc. We do not use foam pads but rather a 1:1 (cubic inch to square inch) ratio of foam to floor surface area in our design which allows modularity and more even impact energy absorption. The foam support layer is independent of the floor panel array. Another aspect of retaining the modular ability of the floor is the possible event of needed replacement of the foam. With additional layers of flooring adhered to the sprung floor, it may make it very difficult if not destructive to take it apart. I don’t know the limit of the rise of the floor you need to consider but virtually any floor height is possible.


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## gafflover87 (Apr 18, 2012)

stevek said:


> Hello gafflover87. For different scenery layouts the support points would be changed.... Successive flooring layers on top of the sprung floor, would decrease the “sprung” aspect of the floor as more structure would decrease the vertical absorptive ability of the floor as dancers land from leaps jumps, etc



Stevek, thanks for the info! Per our needs, it would be out of the question to readjust the floor for everyshow. But it is a good idea. As far as additional layers of material decreasing the effectiveness of the 'spring", that is definitely one of the concerns I have, and will continue to keep that in mind as I look towards the future of this project.


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## stevek (Apr 18, 2012)

gafflover87 said:


> Stevek, thanks for the info! Per our needs, it would be out of the question to readjust the floor for everyshow. But it is a good idea. As far as additional layers of material decreasing the effectiveness of the 'spring", that is definitely one of the concerns I have, and will continue to keep that in mind as I look towards the future of this project.




gafflover87, How often does a production run or does more than one run at a time ? If installation time for a change in shows is very tight it would be challenging. While blocking the area for heavy scene elements would take some time, it may be worth the time or even overtime, if it meant having a sprung floor for the dance performances your venue is considering presenting. The potential draw for dance performance series using a proper sprung floor and being able to support the changes of scenery for your existing performance season is an interesting mix. The portions of the floor that would need to be blocked would be a matter of replacing the foam beneath some floor panels with sleepers or other supportive members the thickness of the foam and later, the foam would be put back in place when a different configuration was called for. I receive requests for our sprung floors from venues that otherwise can't get some dance companies to perform unless it is on a sprung floor. It is a greater issue with those venues where the substrate happens to be concrete.


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