# Stage Floor Acoustic Properties



## Mtnbiker226 (Mar 18, 2019)

My school’s stage floor is in bad shape. It is old hardwood that has dried and deteriorated to the point that even spike tape pulls up paint and splinters. I have proposed covering the stage floor with hardboard (maso or equivalent) as a cost effective solution. However, the music department is concerned with the possible effects on the acoustics of the space. Does anyone know where I might find data to help with their concerns?


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## MNicolai (Mar 18, 2019)

"Acoustics of Multi-Use Performing Arts Spaces", Mark Holden, pg 74

> *Myth #2: Aged and Seasoned Wood has Better Acoustic Qualities than New Materials*
> This is not true. Woods can dry out, split, and crack causing additional sound absorption and reduction in high frequency RT over time. This happened to the thin wood panels and slats at Alice Tully Hall at Lincoln Center in New York City. It is true that lumber used to be thicker (a 2x4 was really 2 x 4 in.) but that thickness difference is of no acoustic consequence. Wood stage floors get worn down by years of rolling pianos, stage riser, and heavy crates and must eventually be replaced. Wood stage floors at Boston Symphony Hall have all been recently replaced with no acoustic degradation.



"Auditorium Acoustics and Architectural Design", Michael Barron, pg 59

> *Floor Material*
> Musicians always speak unambiguously in favour of wood over an airspace as the appropriate construction fo rthe platform floor, because it provides a 'warm' sound. The physics behind this notion has been the subject of few investigations (Askenfeld, 1986). Basically two processes with opposite effects are involved. The floor may be capable of acting as a sounding board for low-register instruments in direct contact with the floor, but it will alsoi absorb sound reaching it through the air. Another possible effect may be the sensation of structural vibration set up in the floor adding positively to communication within the orchestra. The physical studies do not as yet suggest conclusive advantages, yet it would be unwise to contradict the request for this type of floor. In order to allow the floor to be as acoustically 'alive', it should be chosen as thin and within the joist spacing supporting it as being as large as possible, within limitations provided by loading requirements (especially grand pianos), rigidity (e.g. for television cameras), and local fire regulations. A platform thickness of 25 mm and a joist spacing of 600 mm may be regarded as a desirable minimal construction.



It is generally inconsequential to the audience's perspective. Hardboard may be a little more resilient than hardwood though, making it seem to the musicians that the conditions of the room have changed if the stage floor material is a softer when they walk on it and if it vibrates less when they play on it. Just the different sound of sliding music stands around on stage may give them the impression it is an acoustical night/day difference to the audience even though it will have negligible impact on the acoustical absorptivity of your floor assembly.

Personally, I wouldn't stick a layer directly on top. I would remove and replace, whether with T&G hardwood, Plyron, or something else. You want to maintain an even transition to all other areas and sticking a layer of hardboard on top may require you to level out the sides of the stage, connections to backstage areas, and the stage lip to match the extra ~1/4" of thickness.

That's also a _lot_ of screwing into dried out hardwood which will be a pain in the butt today an even worse nightmare when it comes to ripping the panels up later on. If you went that route you would likely be better of doing @teqniqal's alternative fastening approach of sticking panels down with 3M VHB hurricane tape instead of screwing everything into place.

Covering up the sins of today just makes it a bigger and more expensive project when it comes time to do a new floor the right way.

Re: maso, you would also need to select a high grade of hardboard. Don't plan on picking up your average grade hardboard from a big box store or you'll encounter the same problems of peeling up your deck with gaff tape.


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## Mtnbiker226 (Mar 18, 2019)

MNicolai said:


> Personally, I wouldn't stick a layer directly on top. I would remove and replace, whether with T&G hardwood, Plyron, or something else. You want to maintain an even transition to all other areas and sticking a layer of hardboard on top may require you to level out the sides of the stage, connections to backstage areas, and the stage lip to match the extra ~1/4" of thickness




I would love to have the floor completely replaced. However I do not know that the district would be willing with costs and the amount of time it would take the space out of commission. That is why I’m working on alternatives.


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