What batt insulation is best for soundproofing interior walls between bedrooms in a Saint John home renovation?

For soundproofing interior walls between bedrooms in your Saint John renovation, mineral wool batts (Rockwool/Roxul) are significantly superior to fibreglass for noise control. Mineral wool provides roughly twice the sound absorption of fibreglass batts and maintains consistent performance over time without settling or compression.

Mineral wool batts offer R-3.3 to R-4.2 per inch and excel at absorbing sound frequencies in the range of human speech, television, and music — exactly what you want to block between bedrooms. The dense, fibrous structure of mineral wool traps sound waves more effectively than the lighter, less dense fibreglass. In Saint John's older housing stock, where many homes have thin interior walls with minimal sound control, upgrading to mineral wool during renovation makes a dramatic difference in privacy and sleep quality.

For maximum soundproofing effectiveness, install 3.5-inch thick mineral wool batts in standard 2x4 interior wall cavities, or 5.5-inch batts if you're framing with 2x6 studs. The batts should fill the entire cavity without compression — compressed insulation loses both thermal and acoustic performance. Cut the batts slightly oversized so they fit snugly without gaps, as even small air gaps allow sound transmission.

Expect to pay $1.25-$2.00 per square foot for mineral wool batt material in the Saint John area, roughly 50-75% more than fibreglass, but the acoustic improvement justifies the cost difference for bedroom walls. A typical bedroom wall (8 feet high, 12 feet long) requires about $120-$200 in mineral wool batts versus $60-$100 for fibreglass — but the sound reduction is worth the extra investment for better sleep and privacy.

The wall assembly matters as much as the insulation type. For optimal soundproofing, consider these additional techniques during your renovation: use resilient channel or sound isolation clips to decouple one side of the drywall from the studs, install two layers of drywall with Green Glue damping compound between them, and seal all electrical boxes and penetrations with acoustical sealant. Even with standard construction, mineral wool batts alone will provide noticeable sound reduction compared to empty wall cavities or fibreglass.

This is an excellent DIY project for handy homeowners. Mineral wool batts install similarly to fibreglass but are easier to cut cleanly and don't cause the itching and irritation associated with fibreglass. Wear a dust mask, long sleeves, and gloves, but mineral wool is much more comfortable to work with. The batts hold their shape well and won't settle over time like blown-in cellulose might in wall cavities.

Professional installation makes sense if you're doing extensive interior renovation involving multiple rooms, electrical work, or complex framing modifications. Many Saint John renovation contractors are familiar with mineral wool and can install it as part of a larger project. If you're only doing one or two walls, the material cost savings of DIY installation (avoiding the $1.50-$3.00 per square foot installation cost) makes it worthwhile to tackle yourself.

For related renovation work like electrical, HVAC, or window upgrades that might complement your soundproofing project, find contractors through the New Brunswick Construction Network at newbrunswickconstructionnetwork.com.