Sound Insulation Explained

One of the most common complaints of homeowners with income suites is sound transfer from the renters, and likewise with renters, it’s sound transfer from the homeowners. Nobody wants to hear what’s going on above or below, and no one wants to think that they can be heard either. And this is definitely not exclusive to income suites. Nobody in the living room wants to hear noise from the kids yelling and playing downstairs, a television playing upstairs, or dogs barking outside. Noise creates tension, and the less noise there is, the happier everyone will be.

What is STC?

STC stands for Sound Transfer Classification and it gives you an idea of how much sound a material (such as insulation) can stop. Ideally you want an STC of 50 or greater for standard residential walls – meaning you want to block about 50% or more of the noise moving between one unit and another.

Sound Insulation

Whether you want to reduce noise between floors, between rooms, or from outside, insulation is your first line of defence. The fire and smoke proofing insulation that is installed in ceilings and walls is an excellent method of absorbing airborne noises.

Here are a few tips:

  • DO use an insulation appropriate to the space. ROCKWOOL COMFORTBATT® is a thermal batt insulation for use in exterior walls, attics and crawlspaces. ROCKWOOL SAFE’n’SOUND® is an acoustical soundproofing insulation for use in interior walls, ceilings and floors to help create a quieter home.
  • DON’T pack insulation too tight. Always leave an air pocket to help with sound absorption.
  • DO use two layers of Rockwool in walls and ceilings, and leave a little space between them.
  • DON’T forget about interior walls. To further reduce sound transfer put layers of Rockwool between the interior walls of a space. It can add a level of privacy for people living in close quarters.
  • DO make sure to cover the insulation with a sound absorbing drywall.

If you’re not sure how much insulation you need check out Rockwool’s materials calculator for some helpful information.


Special attention should be paid to flooring in upper and lower units of a home. On the upper floor, the proper floor covering will reduce the amount of noise that can travel to the lower floors, while on the lower level the right floor covering will stop noise from bouncing off the floor and onto the ceiling above. This is another reason why installing DryBarrier between the concrete floor of a basement and your floor covering material is a good idea.

More Soundproofing Tips

The majority of your soundproofing will happen during the construction phase of your renovation, but there are some other things you can do after the fact to help dampen sound.

  • DO seal the windows. Windows can create gaps and holes that can provide a way for noise to enter. Weather stripping and new caulk are simple and inexpensive solutions.
  • DON’T forget to look around for any other cracks or gaps. Sound can get through the tiniest of spaces so sealing everything will help prevent it from coming through.
  • DO use thick rugs and underpads. Sound bounces off hard surfaces and is absorbed by soft surfaces, so choose area rugs or carpets with a thick pile and make sure it has a good quality underpad beneath it.
  • DON’T use skimpy window treatments  Heavy fabric drapes will absorb more sound than light fabrics or materials such as wood, vinyl or rattan.
  • DO use soft furnishings to help dampen sound. Opt for upholstered furniture wherever it makes sense.

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