Insulation type, R-values and sheetrock thickness

[BLOOMIS914]

I am finishing my basement for my main theater room and need to know some tips about soundproofing and ways to minimize sound through the floors, vents and stairwell to the upstairs of the house....Can't wake the kids and I like it loud.

1) Srywall/sheetrock thickness--Should I use 5/8" or is 1/2" OK?

2) Wall and Ceiling insulation--Is the Owens Corning Pink stuff ok or should I use some of these solid Polyurethane sheets I have seen at Home Depot/ Lowe's??

3) Depending on answer to Item 2--What R-value should I use R-11, 13, 25.....??? And is one type of inuslation better than the other for sound absorption.

My home was built last year and is very well insulated, so I am not concerned about heat/cold in this finsihed basement as much as I am keeping it quiet from the rest of the house. Ceiling will be suspended ceiling (Armstrong or USG acoustic 2x2 tiles).

Any thoughts, tips, helpful links or books???

Thank you,

Brett

[Hauck]

BLOOMIS914,

For (at least) the first part of your question, I recommend you contact US Gypsum in Chicago . . . I'm sure you can easily find them on the web. They publish the authoritative "Gypsum Construction Handbook" . . . this is a book, not just a cheesy pamphlet. There is quite a section on sound attenuation through various wall construction details. The book is sold at a nominal price by USG.

Phil

[J M O N]

Bloomis,

I am building a house, and actually put double sheetrock on the walls. This was from a recommendation of a local audio store salesman who also recently built a house. This was not for the purpose of sound insulation, but to provide stiffer walls (keep them from vibrating). Since I have K-horns, I thought that this would be even more important. I don't know how much of a difference it will cause, but I'm hoping it will be worth the extra money.

[WMcD]

I'd certainly suggest you read all the books and consult with experts.

However, a few observations. The main theory is that they problably will write about wall to wall transmission, rather than ceiling to floor transmission. So be wary of how the principles are applied in your circumstances.

One main means of isolation between rooms involves having massive walls -- actually so the walls don't act like light weight speaker diaphragms and re-transmit the sound. It may be that the floor of the room above is massive enough simply because it has to support structural weight. It'll be more massive than most thicknesses of sheetrock. Therefore you already have a massive wall in the form of a floor.

Another means to isolate rooms is to have the walls on different studs. That way the studs don't transmit the sound from one piece of sheetrock to the the next. Making a basement ceiling of any significant mass which is not supported by the floor above seems complicated. Perhaps un-necessary.

You will probably also read that the transmission of sound is often through holes which communicate between the two room. Therefore people suggest that gaps in electrical outlets, HVAC ducts, and doors, be sealed. This might be a major problem because the basement is often used as the space where such utilities are routed to the rooms above.

You might take a survey right now in the reverse direction. Is sound from the ground floor being transmitted into the basement? If you can figure out what is allowing that, you might have a better idea of what needs to be cured.

Yeah, really, if you play Pink Floyd on a boom box in the kitchen (while mom and the kid are shopping) perhaps you can identify the problem areas.

There is a Dope From Hope on isolation which I don't have here. (I can send you a copy if you give me your postal address.) Essentially, PWK was trying to isolate a band room at U of Ak. He used maliable sheet lead to seal off chinks in the HVAC system. Some less toxic material could be used these days.

Weather stipping on the door down to the basement could be a big factor! It is probable that you have tons of concrete in the basement walls, and lots of wood or concrete in the ceiling / floor. Yet the door to the basement is made of very light weight material and is not sealing against the doorframe.

My impression is that it is possible to build a Mageaneu Line (sp??? very) and the sound makes an end run.

Regards,

Gil

[RossVTaylor]

Brett,

I posted the following text in another thread and I'm repeating it here. This guide is pretty interesting reading:

There's a very interesting PDF file available for download from the Auralex site. This 18-page "Acoustics 101" has some good info for designing a sound studio. Many of the principles apply to HT. Go to auralex.com, click on the "Intro to Acoustics" button on the top of the page, then download the Acoustics 101 document from the bottom of the next page. Well worth the paper to print it out.