On Apr 28, 4:40 pm, Chris Hill
wrote:
On 27 Apr 2007 18:15:22 -0700, Leeh wrote:

Hi,

I am purchasing a new house (2400 sq ft, 4 bed rooms) in San Diego.
The builder asked me if I want the inside walls insulated just like
the outside. They mentioned two benefits: noise reduction and better
insulation(windows in one room could open). The cost is $1250.
I like a quite house and this seems like a good option to have. But I
don't want to waste money if the benefit is minimum. Any suggstions?

Everything I've ever read indicated that regular fiberglass was a poor
noise insulator. Add to that that the studs still connect the two
sides of the wall and this one just smacks of scam.


Guess you haven't looked very hard. How about Tom Silva, at TOH? He
talks about insulation being useful to deaden sound:

http://www.thisoldhouse.com/toh/know...212626,00.html

"First off, if you want to sound-deaden a room and don't have any
space to sacrifice, there is sound-deadening insulation that can go
into the wall. You can then cover the wall with a sound-deadening
product such as homasote. There's also a product available now that
actually is a sound board designed especially for the purpose. That
wall then gets covered again with a layer of 5/8-inch drywall. "


Or how about this:

http://www.akustx.com/design/Factors...s olation.pdf

" Cavity Insulation Fiberglass or mineral wool cavity insulation can
dramatically improve the STC rating of partitions. STC ratings
increase with thicker cavity insulation up to approximately 4 inches.
Greater insulation thickness beyond 4 inches results in slightly
smaller incremental improvements. There are conflicting data relating
to whether mineral fiber insulation provides better sound isolation
than fiberglass insulation. Mineral fiber insulation manufacturers
claim better sound isolation for their products, due to greater mass,
but this is countered by fiberglass insulation manufacturers. One
factor is clear: while mineral fiber would appear to offer better
acoustical performance by virtue of its density, it is more difficult
to install continuously within stud cavities, and around electrical
boxes, than fiberglass insulation. Since mineral fiber insulation is
more rigid, it can bridge across the GWB and reduce the partition STC
rating. Rule-of-thumb: For wood and S-J structural stud walls, cavity
insulation will increase STC ratings by 2 to 7 STC points. 25-gauge
metal stud or resiliently isolated partitions will have STC ratings
increased by 4 to 8 STC points with cavity insulation. These results
are averaged for both insulation types."



Insulation isn't a total solution. And there are other things you can
do that would be even better, if you have the space and money. But
if you can get some reasonable reduction between rooms in an entire
house during new construction for $1250, it seems like it could be
worth it to me.