Understanding Sound Before You Start
Effective soundproofing begins with understanding what you're actually fighting. There are two fundamentally different types of sound transmission, and they require different solutions:
- Airborne sound: Voices, music, television — sound waves traveling through the air and vibrating through walls and ceilings.
- Impact sound: Footsteps, dropped objects, vibrations transmitted directly through the structure of the building.
Most apartment noise complaints involve airborne sound from neighbours. It's important to set realistic expectations: true soundproofing — blocking virtually all sound — requires structural changes that aren't possible in rented apartments. What you can achieve with DIY treatments is significant sound reduction, which makes a real difference to daily comfort.
Why Mass and Decoupling Are the Key Principles
Sound travels through solid materials. The heavier and denser a wall, the harder it is for sound waves to move it. This is the principle of mass. Adding mass to a wall (extra layers of drywall, dense boards) reduces airborne sound transmission.
Decoupling means physically separating the two surfaces of a wall so vibrations can't travel directly from one side to the other. This is harder to achieve in DIY scenarios but even partial decoupling makes a noticeable difference.
DIY Methods That Make a Real Difference
1. Acoustic Panels
Acoustic panels are frames filled with dense mineral wool or fibreglass insulation and wrapped in fabric. They don't block sound from coming through the wall — they absorb sound energy within your room, reducing echo and reverberation. This makes conversations clearer and reduces the perceived volume of intrusive sounds. They're particularly effective in home offices and music practice spaces.
You can buy ready-made acoustic panels or build your own with timber frames, 50–100 mm thick rigid mineral wool, and fabric stretched over the front.
2. Adding a Second Layer of Drywall
Adding an extra layer of 12.5 mm or 15 mm drywall (plasterboard) to a shared wall increases mass and can meaningfully reduce airborne sound transmission. For best results, use a damping compound (such as Green Glue) between the existing wall and the new layer. This compound converts sound energy into heat as the layers flex, adding decoupling benefit alongside the extra mass.
3. Resilient Bars / Hat Channels
If you're willing to take on a more involved project, fixing resilient metal bars (Z-clips or hat channels) to the existing wall before attaching a new drywall layer creates a small air gap and decoupling effect. This noticeably improves performance over a direct fixed second layer.
4. Seal Every Gap
Sound finds the path of least resistance — even a small gap around an electrical outlet, pipe penetration, or poorly-fitted door frame can allow significant sound transmission. Acoustic sealant (a flexible, non-hardening sealant) should be used to seal all gaps before adding any other treatment. This step is frequently overlooked but often provides one of the best returns for effort.
5. Heavy Curtains, Bookshelves, and Soft Furnishings
Adding mass and absorption to a room through soft furnishings reduces sound reflection and, to a limited degree, absorption of incoming sound. Floor-to-ceiling bookshelves filled with books placed against a shared wall are one of the most practical and attractive ways to add mass. Heavy curtains and thick rugs also help, particularly with higher frequency sounds.
What Doesn't Work (Despite Common Claims)
- Egg cartons and foam packaging: These absorb some high-frequency sound within a room but do virtually nothing to block sound transmission through walls.
- Thin foam tiles: Decorative and minimally absorptive, but not soundproofing.
- Soundproofing paint: No paint meaningfully reduces sound transmission — the mass added is far too small to make a measurable difference.
Realistic Expectations
| Treatment | Approximate Reduction | Difficulty |
|---|---|---|
| Gap sealing | Varies, can be significant | Easy |
| Acoustic panels | Reduces room echo, limited blocking | Easy–Medium |
| Extra drywall layer + Green Glue | Moderate reduction (5–10 dB) | Medium |
| Resilient bars + drywall | Good reduction (10–15 dB) | Medium–Hard |
Even a 10 dB reduction makes a sound feel roughly half as loud to the human ear — a meaningful improvement to quality of life. Start with sealing gaps, then layer up from there based on your needs and budget.