Do you own a duplex or triplex built before the 1980s? You probably know the problem: you can hear everything from one unit to the next. Fortunately, an older plex can be soundproofed without demolishing everything. Here is where to start.
Why are older plexes so noisy?
Acoustic standards were virtually nonexistent at the time, so the same weaknesses often appear:
- wood floors laid directly on joists, without insulation
- lath-and-plaster ceilings, sometimes cracked
- ductwork and plumbing that transmit sound
- poorly sealed openings around outlets and light fixtures
As a result, noise travels through the air and through the structure itself.
Step 1: identify the type of noise
First, identify what is causing the disturbance. Airborne noise includes voices, television and music. Impact noise comes from footsteps, sliding chairs and dropped objects. Each type requires a different solution, making an on-site visit essential before deciding on the work.
Step 2: prioritize the ceiling
The ceiling of the lower unit is often the best starting point for soundproofing an older plex. Work can be done there without disturbing the upper unit. The most common method involves:
- filling the space between joists with acoustic mineral wool
- installing resilient channels or vibration-isolating hangers
- installing one or two layers of 5/8-inch drywall
- sealing the perimeter with acoustic sealant
The new ceiling is separated from the structure and transmits far fewer vibrations.
Step 3: improve the floor upstairs
If you are replacing the flooring in the upper unit, take advantage of the opportunity. An acoustic underlay beneath the new floor covering significantly reduces impact noise. A properly installed floating floor also helps prevent vibrations from reaching the walls.
Step 4: remember party walls and fire safety
Walls between units also deserve attention: mineral wool, wood-fibre panels and double drywall make a significant difference. This work is also an opportunity to upgrade the fire separations required by the Québec Construction Code.
Work one unit at a time
Good news for owners: the building does not need to be vacated. Scheduling work between tenancies limits lost rental income. Quiet units are also easier to rent and attract more stable tenants.
Want to soundproof an older plex in Laval or on the North Shore? See our page on Soundproofing or our multi-unit renovationservice, then request a quote.
