Soundproof a room

Sound travels through air and it travels through the solid building materials that make up the structure of your room; i.e. the floor, ceiling and walls.

So first step, you need an air tight room.

Problem, you need air to breathe. So you need a ventilation system to get air into and out of the room, whilst at the same time reducing the sound transmitted through that ventilation system. For some ideas, we suggest you look at Ventilation Silencer - October 2010 

Next problem, you need to be able to get in and out of the room, so you need to make the door air tight. We suggest you look at Double Door Noise Lock - October 2010

You’ll also need to ensure that all joins, wall-to-wall, ceiling-to-wall, and wall-to-ceiling are airtight using a product like Green Glue Noiseproofing Sealant

Next step, you need to reduce the sound transmitted through the structure of your room; especially applicable to low frequency sound.

Adding mass helps. Note, however that to reduce sound transmitted by about 10dB, you have to quadruple the number of plasterboard layers on your wall. That’s 4 layers on plasterboard on the inside of the stud and 4 layers on the outside; and, similar for the ceiling and floor.

Damping significantly reduces how much the wall, ceiling and floor resonates; the vibrations you feel when you put your hand on a surface near a loud sound source. You can significantly reduce the sound transmitted through the wall with damping; this is where Green Glue Noiseproofing Compound comes in. We suggest you watch the slide presentation to see how it works

Decoupling is valuable. Using double or staggered stud walls will reduce the sound transmitted through the studs. Green Glue Noiseproofing Clips will reduce the sound transmitted from the plasterboard to the stud. Decoupling also improves the effect of added mass, especially at low frequencies. 

Finally, absorption gives just a little more performance. You should add some fibreglass or polyester insulation to the cavity behind your walls, ceiling and floors as it helps to reduce the sound transmitted via air from the internal surface to the external surface. But note, it does very little on it’s own.

An article with more detail is here or call us on 07 3103 0591

Practical Acoustics – facts, not marketing, by Ultrafonic.

We get asked over and over about how to design soundproof walls. The reason varies from recording studios to noisy neighbours. Sadly, there are a lot of myths surrounding soundproofing, most of which are aimed at making manufacturers more money rather than giving customers more soundproofing.

Lets start with “sound” insulation batts. There's no such thing. They are batts. Choose any of the manufacturer's technical manuals and find the acoustics section. They will all show similar data because it is simple physics that has been lab tested and calculated to death.

An empty cavity is bad. However, much more than a simple wall insulation batt only yields a very small increase in soundproofing (typically 1dB) but the cost is much higher. For example, in the table below, a 10mm plasterboard cavity wall on a 70mm stud gets Rw 39 with a Gold Batt but only 1dB more with a Soundscreen Batt.

Have a look at the price difference below that! And these are just examples from public websites selling insulation. There is no real difference between manufacturers. If anyone has other data and prices to contribute, please do. We'll work on adding more over time.

So instead of spending lots of money on very little gain in performance, perhaps we could find other soundproofing materials or techniques that give us more “bang for buck”?

Look at the last graph to see what a huge difference sealing gaps makes. Sealant is cheap and quick to apply. Making the wall airtight by sealing all of the edges and penetrations is likely to give much bigger soundproofing increases than cavity insulation other than a simple batt.

To see how to seal the wall properly, click here

Out of interest, you can also compare how little extra soundproofing you get on bigger studs. In this case you spend more on wider studs and lose floor space.

R2.0 Insulation Batts 430mm - wall & floor pack 22  cover per pack 9.0m2 - $5.85 per square metre for Rw39

$52.69

R2.0 Soundscreen Batts 1160x430mm 8 batt pack  Each pack covers approx 4.43m2 when installed - $11.40 per square metre for Rw40

$50.52

Nearly double the price to go from Rw39 to Rw40

Effect of sealing on level of soundproofing