Replies

1. 
   renosteinke | Mar 19, 2007 08:07pm | #1

   As a simple wild guess, I would say that a regular shape, like an octagon, would cost 50% more.
   An irregular floor plan, one with curves, and junctions at other than 90 degrees, can be as much as triple.

   That's the bad news. The good news is that you really ought to talk to some acoustic - trained engineers, architects, or designers. It's quite possible that major improvements can result from fairly minor changes in the design.

   You are on the right track ... avoiding right angles and hard surfaces. It is especially important that hard surfaces don't face each other.

   Just for the sake of discussion ... let me play with this design a bit:
   I'd begin with a trapezoid for a floor plan, with the altar at the "narrow" end. This need not be a severe shape; I think a 15 degree splay to the walls would be plenty. In a like manner, I'd do the same with the roof, with the low end toward the altar.
   Now, it' likely that you won't want every sound in the altar area to be 'broadcast' to the congregation. So, the area immediately above the altar would have a separate ceiling, set in something like a shaft, that extends above the ceiling edge. Heck, this might be the place for a spire or steeple, as well.

   Apart from the shape, there is the issue of materials. The short side, near the altar, would be a hard material. Here is where the block, concrete, and stone go.
   The side walls would be less resonant. Wood is a good material here.
   The hardest part is the rear wall. There are office partitions that are faced with cloth, and have a padding of fiberglass behind the cloth. US Gypsum is one company that makes these panels (even in 4'x8' sizes), or you might be able to fabricate your own. The rear wall needs to either absorb sound, or let sound pass through ("be transparent").
   Since the floor is hard, the ceiling should be "soft." Ordinary acoustical ceiling tiles should suffice.

   In a less conventional construction, I visited a church in the farm community of Plainfield, Il. The folks there made a church using a 'caterpillar' shaped balloon form, to which they sprayed concrete. This form had superb acoustics ... and has the distinction of being the only building I've seen survive a direct "force 4" tornado strike.

1. 
   CloudHidden | Mar 19, 2007 08:46pm | #2

   >In a less conventional construction, I visited a church...FWIW, that's the stuff I design, but residential only. We're building those for between $110/sf and $185/sf turnkey, depending on finish quality (appliances, surfaces, fixtures).While some elements can cost more, such as framing traditional walls to the irregular shapes of the shell, there are ways to avoid or minimize that. For example, exterior coatings are sprayed, which is fast compared to the piece-work of a shingle roof. As another example, the exterior walls are done when the shell is done, whereas in a frame or ICF house, there's still the need to fit and finish sheetrock, etc. If you use the same materials/methods for a different shape--wood to achieve curves, for example--the cost is usually higher. But if you achieve that shape with different methods or materials, you usually don't have the same cost disadvantage.

2. 
   YesMaam27577 | Mar 19, 2007 11:21pm | #3

   If you are truly interested in acoustics -- having the speaker be heard without much aplification -- then you'll be using ellipses. And in particular, eliptical domes.

   Place the pulpit directly beneath one focus of the elipse, the the largest part of the listeners under the other.

   I grew up in a church with an eliptical dome. The preacher would almost whisper, and be heard.

    

    

    

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