[Crescent]

In the last Home Theater Architect article in SGHT, Russ Herschelmann was describing how to build a basement home theater. In regard to the floor he said to use a floating membrane. Does this mean just a membrane or a membrane beneath the floating wood floor? In the case where it is just a membrane, what is this membrane made out of? How much subwoofer vibration would be transmitted to the viewer? As much as a wood floating subfloor?


I'm about to build an inexpensive home theater in my basement. Do those terms go together? Ceiling height is at a premium as I would like to build a riser for the second row high enough so the second row can view the screen without head obstruction from the first row. I also would not like to compromise too much on subwoofer vibration transmission. Many of my friends are over six foot tall, one is 6'7". I would like them not to hurt themselves in my theater.


The existing basement ceiling height is 7'6".

 

[BGPGuy]

Good luck on ceiling height! I did the floating ceiling room-in-a-room deal with double drywall and now have about 7' 6". I dropped the ceiling about 1.5" with floating joists, and add 1 1/8" for drywall. The ceiling feels low. My soffit actually makes the room feel higher. I am about to build my riser, and find myself torn between using 2x4's or 2x6's. I guess 2x4's would be pointless. Some go even higher, but we are height challenged so....


re membrane, that sounds a little to exotic for me. I think I have read about under floor treatments for moisture control, but never for acoustical benefit.


Oh yes, you will find inexpensive and HT are tough to do, but it is all relative to your wallet size. I think my costs so far are high, but I remind myself of the quote I received for my entire basement finishing; $30k! Weekend HD purchases and my own labor do not seem so bad after all!

 

[Crescent]

Thanks for the reply.


I could use some more experiences please in regard to my questions. If I can put the floor treatment right over the membrane without building a sub-floor, I can build my riser that much higher.

 

[warcher1]

I considered going the membrane way myself, but a vapor barrier type carpet pad was a lot cheaper.


The membrane stuff I think you're talking about comes off of a roll. It has indentations to keep a layer of air between the concrete floor and whatever subfloor you put in. Once you lay it down you will typically put a wood subfloor over it and then whatever floor treatment you like. The membrane is a moisture barrier in itself and the air gap lets any seeping moisture evaporate instead of seeping into your carpet or whatever.

 

[toolcan]

The stuff your talking about goes by a few names It is to be used with a subfloor Usually 5/8 plywood. total height would end up being just around 1" as compared to 2x4 sleepers (PT) on side which would be around 2 1/2" or so .

 

[trunks]

how about this?

http://www.owenscorning.com/around/s...s/floormat.asp

 

[Crescent]

Thank you to all.


I'm looking for acoustical properties. I don't really have an isolation problem as this is a basement floor. I'm fortunate enough not to have a moisture problem either.


This is the only web presence I've found so far that has a similar product.
http://www.acousti-tech.com/en/p31Membrane.asp. (don't know how to hyperlink it).


Can it be carpeted over directly? Does it actually transmit the subwoofer vibration as good or close to an actual sub-floor?

 

[AFryia]

The membrane could be "Delta-FL" or a similar product. It comes in either a roll then you add 5/8 flooring on top or you can get "Subflor" a 2x2' T&G OSB panel with the dimples on the bottom.


The purpose is moisture control/barrier allowing the concrete to breath on the bottom side while keeping the top side dry. None of the sites I've seen note acoustical properties.

 

[trunks]

Quote:

Originally posted by Crescent Thank you to all. I'm looking for acoustical properties. I don't really have an isolation problem as this is a basement floor. I'm fortunate enough not to have a moisture problem either.

Did you follow the link I posted for QuietZone Acoustic Floor Mat? The page has a link to the product data sheet and installation instructions. We install this in all of our Visionaire FX theaters.

http://www.owenscorning.com/around/s...s/floormat.asp

 

[Dennis Erskine]

There is another product available from Plate-Forme CPT, Inc. that has proven superior for this kind of application as well as sound isolation. It comes in 2'x2' squares, 5/16" thick and 7 lbs. each. The company does not have a website, but you can fax them at 418-682-6636 and ask for information on their Acoustik mat. Unlike Owens-Corning, Plate-Forme does publish the results of acoustic testing on the product. O-C's product sheets only publishes the ASTM-84 flame spread testing...hence, they are not responsible for, or warranting, it's acoustic performance. Again, I'd remind all that regardless of source or brand, do not purchase a product claiming acoustic benefits without first getting the results of independent field or laboratory testing.

 

[trunks]

Quote:

Originally posted by Dennis Erskine There is another product available from Plate-Forme CPT, Inc. that has proven superior for this kind of application as well as sound isolation.

Proven by who?

Quote:

Again, I'd remind all that regardless of source or brand, do not purchase a product claiming acoustic benefits without first getting the results of independent field or laboratory testing.

Independent field tests can be incredible, or unreliable. Laboratory testing can also be unreliable or even faked all together. I have seen Owens Corning's Acoustical Research Laboratory, including their full anechoic chamber, considered one of, if not the, most advanced in the world. I told a friend about it, and he pulled out one of his college level physics text books that had pictures of OC's chamber in it.

My point is that I trust Owens Corning's testing facilities and acoustic engineers. I trust that a product they release will perform as described. Maybe they have ulterior motives for not releasing acoustic specs (didn't want somebody to steal their specs, and design their own product around them...?)

I am not saying that Plate-Forme's product is not better, which it very well could be. I am not saying that quietzone acoustic floormat could not be discredited, although I doubt it, IMO it works quite well.

I guess I just have different standards for deeming a product credible. Maybe you have seen some reviews/specs/tests that I haven't??

 

[Dennis Erskine]

The Plate-Forme product has been tested (FIIC 62...meaning field testing) and ASTM (IIC...laboratory) as well as to European field and lab tests (Delta 28). These results are published and specified in their product sheets. In a similar manner, Johns-Manville includes the results of ASTM tests for every product they claim has an acoustic benefit.


O-C certainly knows the performance metrics of their products and they certainly have the right, for whatever reason, to withhold that information. It is, none-the-less, generally good practice not to purchase products for which the product's performance is unknown or undisclosed. In our practice, we cannot.


Knowledgeable consumers are certainly free to utilize those products they feel most comfortable using. We are directly familiar with both products and some other, similar, products. In the end, I still believe the better advice is to never purchase a product for its claimed acoustic properties if the manufacturer cannot substantiate those claims in a meaningful and consistent manner (meaning the use of recognized tested methodologies).

 

[Crescent]

Please tell me how these different products install (nails, screws, glue) and the layers (concrete, treatment, plywood, carpet)?


for example,


membrane sits on concrete

5/8 plywood nailed through membrane to floor

Carpet tack-strip to floor


If this membrane is punctured, like with a nail, do the low frequencies not get transmitted as well?

 

[settopguy]

You are correct that nailing or screwing through a membrane will conduct vibrations through nails/screws down into the floor. That would reduce the benefit of the membrane.


You would have to check with the manufacturer for installation suggestins, but I think in general you would want some type of flexible adhesive.

 

[Crescent]

Thanks again to all.


Trunks, that's the stuff. The new issue of SGHT came out and he specifically references an Owens-Corning product. Do you know where I can go to purchase it if it comes to that? I've already checked Lowe's and Home Depot.


I will check out this Plate-Forme product. Why do I have the feeling it's going to be expensive?


If all else failed, wouldn't a good thick carpet pad do the job, as warcher1 suggests? Rubber or felt?

 

[Dennis Erskine]

There are individuals on this forum who've used the Acoustik Mat and can prehaps provide some guidance as to sources and prices.


The material itself is 5/16" thick, comes in 2' x 2' squares, weighs 7 lbs each, and is a very dense, high mass rubber based material installed with glue (hence it's performance on low frequencies). A 14 x 20 room would then use 70 tiles (490 lbs). You can contact Plate-Forme CPT in Quebec at 418-682-5587.


Plate-Forme CPT, btw, is a non-profit organization.

 

[Crescent]

Thank you Mr. Erskine. I've read many of your posts and respect your opinion. I think I might get killed on the shipping alone, 490 pounds to Connecticut. I will check, though.

 

[Dennis Erskine]

Where in Connecticut? we'll be using the material on a project in that state within the next week or two.

 

[melvin s]

I'm a little confused here. Why would you want to put an expensive acoustic matt underlayment on a basement floor? Unless you have some occupied space that is beneath the basement floor, impact isolation won't be much of a concern. If it is impact isolation that you are truly concerned about (which would still be somewhat confusing) a carpet on pad would give you satisfactory results. As far as the acoustic benefits of the matt, what are you looking for? The fact is that the underlayment won't help from the airborne sound transmission standpoint and the IIC also isn't much of an issue. I think that your money would be well spent in other areas.

 

[Dennis Erskine]

I may have missed the fact this is a basement, slab floor. In which case, Melvin is correct.