I'm in the process of finishing my basement. The ceiling is (will
be) a drop ceiling. The rafters above the drop ceiling don't have any
insulation in them. The basement is where my home theater will be, so
sound insulation is of high importance. My local hardware store carries
Johns Mansville insulation, and I decided to get kraft faced insulation
for ease of installation. I was wondering what thickness of insulation
to buy. The rafters are 9 inches deep (and 15 inches wide). The two
thickness of insulation I was looking at are 8 1/4 and 10 1/4. I didn't
know if it was better to go with the 8 1/4 and have a small gap or go
with the 10 1/4 and compress it a bit when I install it. Here's the
brochure for the insulation if that helps:
. Also, I live in South Dakota, if that makes any difference.
If you want sound insulation, I suggest you don't bother trying to make
do with heat insulation.
Check out: http://www.soundproofing.org /
In general you want to block air exchange. Air caries sound very well.
(Try opening your car's window as a train is going by.)
Next you want weight. Heavy things (drywall lead sheets etc.) block
You also want to prevent any direct solid connections. Stagger wall
studs or use special isolation devices to keep the sound from traveling
through the wall (remember the two cans on a string (well wire actuarially
worked) you want to break the wire).
Filling in wall cavities with sound absorbing materials (accustical
fiberglass bats) will do a little.
Point source control (special absorption material) at the source of the
sound will also help.
Thanks for the info. I checked out the site and will try and implement
some of those ideas along with the insulation. I have to install the
insulation regardless of it's soundproofing abilities because it's a
basement in South Dakota, so insulation is pretty much a requirement.
Joseph Meehan wrote:
Crud, I dunno...I'm a self-admitted dummy when it comes to this stuff,
that's why I ask. I guess I was thinking: Hot air rises, cold air
settles, so I'll install insulation in the ceiling to keep all the warm
air from rising to the upstairs and all the cool air from settling in
the basement, thus keeping the temp of the two areas similar. Am I
flawed somewhere in my thinking.
Edwin Pawlowski wrote:
You should think about temperature and moisture differences between the
two areas. The kraft paper acts as a vapor barrier, so if the basement
is colder than the upstairs, moisture can condense in the insulation.
Maybe someone with more experience in your area can give you some idea
of common practices.
There are really only four tricks to limiting sound transfer:
Closing off air gaps, decoupling surfaces, weight, and
getting rid of large flat reflective surfaces.
So you start by spraying a thin layer of urethane foam
on the underside of the floor. This seals any open
air passages, adds a tiny but of mass, and creates a
bumpitty surface to break up sound. Then you stuff
some asphalt roll roofing into each rafter bay,
holding it up with wire. After that, if you have
the headroom, you stick resilient-channel crosswise to
the joists (cheap, but takes a lot of space) or
add 2x6 joists between the existing floor-joists,
only with the bottom edges 3/8" lower, and
attach 1 layer of homasote 440, and one layer of
1/2" sheetrock to that.
If, for some reason, you must use a suspended
ceiling, invest in a great many extension springs,
(tearing apart certain kinds of bed is a good way
to find those) And cut up a bunch more squares
of that asphalt roll-roofing to put on top of
the tiles. to add weight. Use the heaviest
metal gridwork you can find.
If you have ceiling-mounted light fixtures,
move them to the walls, since they form a
pathway right past your sound-deadening
Remember that you are no longer going to be
able to hear things like telephones,
fire-alarms, and doorbells through the
floor, so you'll want some sort of repeater.
I put in encapsulated r14 insulation in there. (walls and ceiling)
The sound deadening worked out ok. Its not like someone can
scream down there and not be heard, but you dont hear much
upstairs when the tv or stereo is on.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.