A topic that is often covered by many online resources aimed at the DIY audience, there is a great deal of misunderstanding and misinformation around this topic. Similar to other articles on this blog, we’ll try to briefly explain the complex subject in this post.
First and foremost, it is important to keep in mind that a building (or a room for that matter) can never be 100 percent soundproof room. At least, not with the commercially available materials today. However, despite this fact – there are a number of ways to keep sound out or within reasonable levels. This brings us to the second frequent misunderstanding of confusing “soundproofing” and “sound treatment”. The first is a term used to refer to reducing sound transmission, whereas the latter means to tame acoustics within the room. There’s a huge difference between these two things, and they’re not interchangeable.
Soundproofing an existing structure can be pricey without guaranteed results. The general rule of thumb is that high-frequency sounds – such as music and children’s cries – are best treated with lightweight materials (mineral wool fibre). They can be added by putting up a new timber stud wall next to the party wall and inserting the mineral wool in the spaces between the studs, then plasterboarding over. There are proprietary products as well, such as the Gyproc’s Triline system, where the insulation is attached to a sheet of plasterboard and stuck to the existing wall of the structure.
Lower frequencies (common in populated urban areas) are better stopped by dense materials like concrete blockwork. Since relaxing regulations party walls have no longer been built solely from concrete blockwork and timber and plasterboard have found their way in commercial construction as well. It is unreasonable from a financial, space and labor-wise point of view to put up a concrete block wall on the side of the party wall that needs to be soundproof.
Instead, other proprietary products can be sought out, such as plasterboard sandwich materials that incorporate layers of dense vinyl. These are widely used in recording studios. In general, it is a good idea to have a professional visit the building and do some decibel readings from a sound-level meter to determine that the noises that come inside are within acceptable limits before proceeding with any soundproofing modifications to the existing structure.