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Discussion Starter #1
Hello,

I'm planning to use Roxul safe n' sound for acoustic insulation in my basement. Primarily for the home theatre room.

I noticed the safe n' sound (for wood studs) is only available for 16" stud spacing (or 24" by special order), and is 3" thick. My ceiling joists are 12" tall and are spaced ~19" apart.

I've resigned myself to the fact that individual strips will have to be cut to make up the full width between joists. But my real question is should I double up with two layers in the ceiling above the home theatre? Since each piece is only ~ 3" think, and the joists are 12" deep, two layers would still leave a good air pocket in there.

I'm just wondering what others have done and whether its worth doing 2 layers vs. 1 layer.

Thanks!
 

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Roxul compresses fairly easily so I would just push 24" batts in the 19" space. You might want to consider a suspended ceiling with a 3" space between the joists and ceiling. Then lay the Roxul batts in the space. With drywall attached directly to the joists, the Roxul will do little to stop sound leakage.
 

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Discussion Starter #3
I'm going to be installing Kinetics iso-max clips with furring channel, therefore the drywall will not be directly attached to the joists.
 

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Inzane,

Give Roxul a call... I know they are in Milton ON, they might have an office in Western Canada.... When I spoke to technical support there, they said that a double layer is minimally more effective than a single layer. They advised me to use the money elsewhere.... better doors, heavier drywall etc etc.

P
 

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Should the insulation be pressed up to the floor above or should it sit on top the drywall? Where should the airspace be?

Thanks
Greg
 

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Discussion Starter #7
The diagrams I've seen on both the Kinetics and the Roxul sites suggests the insulation sits at the bottom of the joist, with the air space/void on the top.

The insulation won't be sitting right on the drywall because the furring/hat channel runs perpendicular to the joists.
 

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I did single layer, right up against the floor above when possible....

main floor
roxul
airspace
hatchannel /isomax
5/8" Drywall
green glue
5/8" Drywall

was what I did.

I used pink instead of roxul in joist cavities that had HVAC or plumbing running through them.... I found pink easier to lightly stuff in irregular spaces then the Roxul product.

P
 

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Discussion Starter #9
Hmm.... I'm still curious how much incremental difference the green glue makes, all else being equal.

It just seems to be such a large cost adder, compared to everything else.
 

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re: green glue.

Hard to say. I am happy with my room. Green Glue was a favourite among AVS forum members a few years back... there was at least a 100 page thread on it.

It does add expense, I can't remember exactly, but my guess is somewhere between 1000-2000 to the cost of my basement.

I have a lot of bass, plus bass shakers in my seat, and I can watch stuff as loud as I want. I'll be using the room for the next 15-20 yrs. It's probably only needed for the next 15 yrs or so... My kids go to bed at 8pm, and in about 10 yrs, they'll start inviting friends over, and then they'll watch stuff sans dad, and it won't bother me. In about 15 yrs,... they'll hopefully both be off to school....

P

PS. Looking on the net, looks like it costs $15/tube. I think I bought 5-6 cases of it, and then sold a part case on kijiji that I had left over, so call it 5.5 cases?

5.5 x 12 x 15 = $990 best guess.
 

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Just as a point of interest from what ive read here and other forums, the Roxul is best for thermal insulation, but the pink fiberglass makes a better sound proof insulation and if I remember correctly it comes in the 2x6 sizing for floor joists. Some people have also done 2 batts to completely fill the joist with great success, again just going off what Ive been reading. If im wrong please correct as I'm coming up on this same section of my ht build.
 

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Discussion Starter #12
the Roxul is best for thermal insulation, but the pink fiberglass makes a better sound proof insulation
That seems exactly opposite from how those two products are marketed. :confused:
 

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Not true Roxul is made of ground up rocks and wool which we all use to keep warm when it's cold out ( wool that is) and roxul comes up to r14 for 2x4 walls, pink does not and it is more dense to provide a better thermal break. As far as the fiberglass for soundproofing you could use the same example as they discussed a couple threads down from here regarding drop ceiling tiles. Painting them fills in the textured crevices designed for sound deadening. Take that and apply it to fiberglass insulation. It's less dense which provides more "pockets" if you will to dissipate sound.

Again this is just what I've researched either point could be argued.
 

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I have 2 layers of roxul sound insulation in the ceiling, with sound channel to help decouple the drywall, then 2 layers of drywall on the ceiling. I didn't bother with green glue as I felt the expense was just too high, and I found it hard to believe that it could possibly make that much difference. Overall the sound control is OK, but I do have 2 bedrooms with laminate flooring above the theater, and the sound from the theater isnt a huge problem. I can watch a movie at moderate levels with the bass turned down when the kids are in bed. Where I do notice a problem is when one of the kids drop a toy or something on their bedroom floor and I am watching a movie. It is almost like there is nothing dampening the bang of the object hitting the laminate floor above me.
 

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Discussion Starter #15
Insulating staggered stud walls?

Hello Again,

I'm at the stage where I need to estimate quantities of insulation so I can order and have it delivered. I'm getting 24" wood stud batts of Roxul safe & sound for my basement ceiling (19" joist spacing). And I'm getting 16" wood stud batts for most of the interior basement walls.

For the home theater room, the interior walls are constructed as a staggered stud wall (2x4s alternating over a 2x6 cap. 16" center on one side, or 8" center if you count from alternating stud to alternating stud).

My question is. Should I double up and stuff the safe n' sound on both sides of the staggered wall? The batts are ~3" thick, so they'd compress ever so slightly between a stud and the drywall on the opposite side. This would leave almost no air space. The other option is cut the 16" batts down the middle length wise and put the strips (essentially ~8" strips) between each stud, which would leave a gap/void of air.

I'm not sure which is the preferred philosophy for sound isolation in walls. Keep some air void, or minimize it?

Just for reference: For drywall, I'm either doing a single layer of 5/8s, or a double layer of 5/8s, or one layer of 1/2 and one layer of 5/8s. Still deciding. (no green glue or sound clips on the walls).

Let me know what you think.

Thanks!
 

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Inzane, mct123,

Where do you read that more Safe and Sound is better?

My staggered stud wall is only 1 layer of 3" S&S.
I actually cut out/ carved out a strip in the middle with a bread knife for the 2x4 that doesn't go all the way through. If you search AVSforums or Roxul, there may be a picture demonstrating this

There is a science to Sound Proofing for DIY HT enthusiasts. There is also a lot of marketting. Sometimes it's hard to tell the difference.

I did stuff in my HT that would be frowned upon in a normal basement reno.

For example,
My 20x25sq ft room doesn't have any HVAC. None, notta. It does have 3 doors that I can open if it gets stuffy, but it hasn't been a problem. It's a bit cool down there, but nothing a throw on the couch won't solve.

I didn't want to open up a potential sound channel from my HT room to the rest of the house.

I gave up ceiling pot lights to preserve my soundproofiness. I have 4 pairs of wall sconces for my lighting.

There are a couple people here who have done HT rooms that have spent more on wall sconces than I did on Green Glue. It's all about priorities....

P
 

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Discussion Starter #17
I didn't say more is better. I was ASKING if more is better. ;)

Do you have a link with a picture? (with carved out strips).

I've been searching AVS and it sounds like generally speaking guys over there are not favoring Roxul safe n' sound. :confused:
 

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Inzane,

Sorry no pictures. I have minimal pics of my HT build.... I was working solo most of the time... Wife was busy with the kids at the time ( 2 and 5 yr old).

It's easy, S&S cuts like bread. I just cut out a strip in the middle to give relief for the 2x4 that was in the center of the batt. Similiarly to cut out electrical boxes etc.

You could also look for some pink (I think Owens Corning made it) that came in a roll for stag. stud walls. You could weave it in between the studs.

re: Roxul. and AVS

Might have to do with availability of the product. I think Roxul is Cdn. maybe the penetration in the US market isn't as good
 

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Petee C, I did my room similar to you, removing any HVAC, and went with wall sconces instead of pot lights to eliminate any holes in the ceiling. I don't know if more safe n sound made a difference or not, but everyone I talked to said safe n sound would be more effective than fiberglass at sound proofing. I have fiberglass in the ceiling of another room in the basement (used it only because it was removed from another area of the house, I had to do something with it) and I do find the safe n sound more effective at sound deadening. Did you use green glue, and if so, do you think it made much difference?
 
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