Skip to main content

Example from Roxul: insulating a home theatre room

I liked this video from Roxul because the presenter clearly explains the difference between the two types of noise: airborne and low-frequency noise, which I will add to here.

The lower frequencies travel through the wood studs. A low frequency travels from your wall surfaces, floors, and ceilings if they sit directly on those studs. Lower frequencies include bass from your stereo, impact sounds from walking or pounding, trucks driving outside, and maybe the spin cycle on a washer.

Roxul insulation mitigates the other kind of noise -- airborne noise -- which can include talking and TV (without bass). This insulation product is dense and does a really great job of blocking airborne noise. However, if it's used alone, it doesn't stop low-frequency noise.

The presenter shows how to insert Roxul batts between the studs, which you've seen before. Then he installs a resilient channel to keep the drywall from touching the wood studs. The resilient channel's job is to reduce the low frequencies that might get passed into the wood framing.

The first layer of wall is installed horizontally. Then he installs a second layer of drywall on top of the first layer, and this time he installs the drywall vertically, so the seams of the second layer don't overlap the seams of the first layer.

I think everything in his process is really solid, but I would have done one more thing: I would have also applied some Green Glue to the second layer of drywall before I installed it. Or I would have used a soundproof drywall (like QuietRock) for at least one of those layers of drywall.

Here's the video from the ROCKWOOL North America channel: 

 

NOTE: just in case the original YouTube video gets moved again, be sure to also enjoy this video about using Roxul with resilient channels, from Michael Dominguez.*

If this is a remodel, it already will be superior to the previous construction and it will reduce the noise coming into and out of that room. However, I think there's a missed opportunity here: if he'd applied Green Glue between the two layers of drywall, it could absorb some of those low frequencies before they even get to the resilient channel.

Comments

  1. mahnamahnaFebruary 11, 2018 at 12:28 PM

    Great blog! Here's a question: In sound-insulating an existing floor/ceiling, should I (1) blow in cellulose, or (2) add Green glue and an additional layer of sheet rock? Or do I need to do both?

    This is a simple construction, recently renovated, with drywall ceilings below wood joists, then plywood and wood floors on top of that. No insulation. Right now conversations/TV at normal volume and footsteps are coming through.

    I don't need perfect soundproofing but need a bit more sound protection than we've got currently. Thanks for any help you can offer.

    ReplyDelete
    Replies
    1. attituneMarch 17, 2018 at 9:06 AM

      Blowing in cellulose definitely helps to mute conversation noise. It won't mute footsteps or any impact noise. I have no personal experience with adding an extra layer of drywall to a ceiling with Green Glue (only to walls), so I don't know how effective it is. I've seen reviews on the internet from people who say it's less effective on ceilings than on floors, and they advocate a drop ceiling with additional drywall, which is fairly effective.

      Delete

Post a Comment

Popular posts from this blog

Blow-in cellulose and your hollow walls

It's not too late to insulate.  A few years ago, most American homes had no insulation in them. When a homeowner did insulate, it was usually with fiberglass batts. Then along came some better products. One of them is blow-in cellulose insulation. Does it work? I can attest to this: YES. I've used it in walls and ceilings, and it works quite well for airborne noise. If you live in an uninsulated home and you hear your neighbors voices coming through your walls or ceilings, cellulose will dampen that noise or mute it entirely. It doesn't work for all types of noise. But it doesn't eradicate impact noise. You might still hear the sounds of someone walking across a bare hardwood floor with their shoes on, for example, or hear wall-mounted cabinets opening and closing. There are other solutions for that, and by combining different solutions you can control most structural noise and create more privacy. Low cost Blow-in insulation is inexpensive. You can hire a
Post a Comment
Read more

Combining QuietRock and Green Glue together

Two great products work great together. As I've mentioned before, I'm experimenting around with ways to reduce some of the noise problems in my apartment on a tight budget. I think I've found the best combination to date: adding a layer of QuietRock 510 over an existing layer of gypsum drywall with a layer of Green Glue inbetween. This was sort of the best of both worlds: taking a pre-made, sound-dampened drywall and then adding it over a powerful, viscous layer of glue....onto drywall that was already on the wall studs. No demo needed. In this project, I basically added two sound-dampening layers to the original 1950s drywall (one layer in the QuietRock and the other layer created by the Green Glue) to address " flanking noise ": feet, furniture, and shoes pounding on the bare floor of my downstairs neighbors' apartment. The amount of banging, bashing, and foot-stomping sounds coming from their very "wooden" apartment has been severe, and I&
10 comments
Read more

How to measure decibels and frequency with the Decibel Meter app

 Frequency matters When you're dealing with a noise issue, the frequency of that noise is just as important as the decibel level. A decibel is the loudness of the sound, and measuring decibels can alert you when a sound is more than just a nuisance, but dangerous to your health. However, decibel levels on their own don't tell the whole story. The frequency of the sound is also very important. The frequency is a measure of how many sound waves per second are produced by a sound, and determines its pitch. A low-frequency sound might be really annoying, but it might not be that loud. The lower frequencies are typically below 150 Hz, and often sound like a deep bass sound that's not necessarily loud, but the vibrations from that sound can travel through the entire frame of a building and disrupt sleep or cause stress. Knowing both the decibel level and the frequency of an unwanted sound can help you determine the right soundproofing solution. For example, a low-frequency nois
Post a Comment
Read more