H.D. green fibrous insulation

[Ivan]

I was in HD today looking at insulation. I saw something new (to me). The propaganda on a certain brand claimed it had extra "sound proofing" qualities. The product was green and seemed softer than the regular pink fiberglass insulation. Not as soft as Charmin, but still softer and almost woolly. Does anyone know about this brand? Would the sound proofing qualities be that much more than pink fiberglass? I'm going to be stuffing insulation in the joist cavities in a down stairs room. Ivan

[Joseph Meehan]

It appears it helps a little. Even standard insulation helps a little.

How happy you will be depends a lot of the type of the noise and the construction. High frequencies and low frequency sounds don't react the same.

Generally the best and cheapest answer is increased mass. An additional layer of drywall is usually the biggest bang for the buck. Lead blankets behind the drywall helps a great deal, but cost more. Isolation techniques that provide a break from one surface to the other (like staggered studs or isolation strips) can be very useful.

Often the problem is a result of the sound taking a short cut. Any air to air connection is going to be a problem. Heating ducts and cold air returns are a prime example. It is also important to consider that the sound might find it easy to go up through the ceiling, across and down through the ceiling in the next room.

Windows and doors are also common problems.

If the source is very local like a washing machine, that can often be addressed directly.

Take a look at:

For some ideas.

[SQLit]

green stuff in small bales, right? it is cellulous, ground up newspaper with a fire retardant.

I just had r-19 installed over the existing ~r-30 ish plus r-30 over the garage which had nothing. It was cheaper to have some one do it than it was to buy it at the home center.

Insulation works because of the air spaces. Tightly packed areas will not insulate more than loosely packed.

As for the sound it will help some. depending on your situation, there is a black fibrous board (4X8 sheets) that I have seen installed under drywall that seems to help sound transmission.

[Ivan]

Would that fibrous board be called "buffalo board"?

I remember meeting someone who saved all his drywall scraps and cut them into pieces 3 1/2" wide. He laid them down inside the wall cavity as a sound proofing method. I never did find out how that worked. I was wondering if something similar would work inside the joist cavities. I would never try anything this silly but I'm visualizing lining the joists and bottom of the upper subflooring with drywall.

Ivan

[Art]

I lined a bathroom wall and ceiling with regular insulation. Did not seem to help at all with noise. Tinkle... tinkle..... tinkle flush!

[Bob in CT]

You can search the internet for sound proofing techniques. One thing that helps are metal channels that you connect to the studs and then to the drywall -- this decouples the drywall from the studs somewhat. Better is this and sound reducing insulation. Better is two walls, with the studs offset. Better is two complete walls separated by an airspace. Search for "sound transfer coeffiecient wall" or "STC wall".

[default]

Or homasote soundboard.

Pure weight is a significant part of stopping sound, as is chopping up any empty space into random-sized volumes.