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Roxul sound proofing opinion

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[OP]
Deal Addict
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Nov 10, 2003
1949 posts
5 upvotes

Roxul sound proofing opinion

I'm currently finishing a basement in my house, and am planning on putting Roxul Safe'n'Sound insulation in the ceiling between the joists, to stop the transmission of sound up into the mail floor of the house.
The house is older, and the joists are 2x6,s (16" on center) and I am debating on whether to put in one layer of the Roxul stuff or two. The Safe'n'Sound stuff is only 3" thick, so I can physically fit. It's just a question of the effectiveness of $200 worth (second layer) of Roxul will make a huge difference or not.

The final ceiling will be suspended ceiling tiles.

Any thoughts on this? Will a second layer of this stuff make a huge difference?
23 replies
Deal Addict
Mar 21, 2006
4314 posts
344 upvotes
Burlington, Ontario
More insulation will help, however it would be difficult to say how much.

Sound will still vibrate through the solid wood joists. You cannot get rid of that unless you isolate them too.

Think of this as sound dampening, not sound proofing.
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Deal Addict
Mar 31, 2003
4113 posts
51 upvotes
Cambridge
I've done this, the 2nd layer won't do very much.

Having a suspended ceiling will help more than a 2nd layer as you will add another medium and an air gap.
[OP]
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Nov 10, 2003
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Steve,
How did you determine that a second layer doesn't add much?
Did you do any testing with just one layer and then 2 layers?
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Nov 18, 2007
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Valleywood
I had the same decision, but chose to go with the standard 5 1/2" Roxul batts.
[OP]
Deal Addict
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Nov 10, 2003
1949 posts
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Why did you choose the 5 1/2 bats over the safe'n'sound stuff?
Jr. Member
Jun 18, 2006
115 posts
33 upvotes
Outsider wrote:
Apr 8th, 2008 8:10 pm
I'm currently finishing a basement in my house, and am planning on putting Roxul Safe'n'Sound insulation in the ceiling between the joists, to stop the transmission of sound up into the mail floor of the house.
The house is older, and the joists are 2x6,s (16" on center) and I am debating on whether to put in one layer of the Roxul stuff or two. The Safe'n'Sound stuff is only 3" thick, so I can physically fit. It's just a question of the effectiveness of $200 worth (second layer) of Roxul will make a huge difference or not.

The final ceiling will be suspended ceiling tiles.

Any thoughts on this? Will a second layer of this stuff make a huge difference?
You would be better off using a layer of Drywall and Greenglue in the joist cavities. I've used it with great results.

http://www.greengluecompany.com/pdf/upg ... iagram.pdf
Deal Guru
Dec 31, 2005
13193 posts
668 upvotes
We have the Roxul and the drywall ceiling is mounted on rails/channels to minimize sound transfer....It works very well.

House is a 1930's/40's Semi in Midtown.
Deal Guru
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Feb 24, 2003
12174 posts
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Toronto
I have Roxul Safe 'n' Sound as well in all of the walls and ceilings of my renovated home and it definitely made a difference. I can't tell whether Safe 'n' Sound is better than other methods available to reduce sound transmission through walls and floors because I didn't have time to experiment during the renovations. Sound still escapes from the basement through the air ducts and there's not much I can do about it since I have to heat and cool the house.
Deal Addict
Aug 24, 2002
3569 posts
19 upvotes
Sask
hagbard wrote:
Apr 9th, 2008 10:07 am
Canadian Housing and Mortgage Corporation has information on soundproofing between floors. Check around on their site. Most of this insulation stuff doesn't work.

http://www.cmhc-schl.gc.ca/publications ... /90246.htm

http://www.cmhc-schl.gc.ca/publications ... /90247.htm
While you are right that regular fibreglass insulation doesn't do much to dampen sound, the Roxul Safe & Sound does a LOT.

Roxul has a demo station where they have one box packed with regular insulation and one packed with their product. They put a person alarm (the kind joggers use if they are afraid of being mugged) inside and set it off.

The regular insulation one hardly dampens the sound, the Roxul box is near silent.

That said, I would agree from personal experience you'd probably do well to use one layer of Roxul S&S and put the rest of your effort to other things like dampening the ceiling board, joists, and other vulnerabilities.
Deal Addict
Mar 31, 2003
4113 posts
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Cambridge
Outsider wrote:
Apr 9th, 2008 9:17 am
Steve,
How did you determine that a second layer doesn't add much?
Did you do any testing with just one layer and then 2 layers?
I did one room with 2 layers and one with 1 layer. The difference is in my head.
Sr. Member
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Mar 29, 2003
817 posts
1 upvote
I've done 2 layers and it helped sooooo much. I only could do that in my main floor bathrooms ceiling. We lowered the ceiling so we could squeeze 2 layers of the roxul. Before I could hear the guy upstairs farting and peeing and walking around. I dont hear anything anymore. I did 1 lay in the bedroom and I can still hear his music and him walking around. But its a lot better than with no insulation. Get the 2 layers.
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Newbie
Mar 23, 2013
3 posts
Oshawa
There are measures you can take to reduce sound transmission through ductwork.

Sections of flexible duct can be utilized.
Duct mufflers can be fitted.
Dynamat can be inserted into register entrances.
Antivibration coating can be applied to outside of ductwork.
Insulation socks can be pulled over steel ducts.

I am in the middle of renovating basement and installed a duct muffler on the duct that runs up to the master bedroom.... and pulled duct insulating socks over many of the longer runs..... also removed sections and replaced with small sections of flexible duct in areas where flow was not an issue. I also coated the supply and return headers with antivibe.

I can now work on the basement at night, with my wife saying she can hardly hear anything. Before, if I had the radio on low, or tried doing anything down there..... she would get woken up.
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Dec 19, 2001
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Fernando Po
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