How much does it cost to add a second layer of drywall with Green Glue for sound isolation?

Adding a second layer of drywall with Green Glue is one of the most cost-effective soundproofing upgrades available, and for a typical Ottawa wall or ceiling, you can expect to pay $8 to $14 per square foot installed, or roughly $1,200 to $2,500 for a standard 10x8 foot wall.

What Goes Into That Price

The material costs break down clearly. 5/8-inch Type X drywall runs $14 to $18 per sheet in Ottawa — always use 5/8-inch rather than 1/2-inch because the extra mass makes a meaningful difference in sound blocking. Green Glue Noiseproofing Compound costs $15 to $22 per tube, and each tube covers roughly 32 square feet when applied correctly. For that same 10x8 wall (80 square feet), you are looking at approximately three tubes of Green Glue, meaning $45 to $66 in compound alone. Add acoustic caulk at $8 to $15 per tube to seal the perimeter and any penetrations, and your material cost for that wall lands somewhere between $200 and $350.

Labour makes up the larger portion of the bill — typically 50 to 60 percent of the total cost. Hanging a second layer of drywall with Green Glue is more involved than standard drywall work. The compound must be applied in the correct pattern (two tubes per sheet in an S-curve or blob pattern, avoiding the edges), the panels need to be offset from the first layer's seams, and every perimeter joint must be sealed with acoustic caulk rather than standard compound. Rushing any of these steps reduces performance noticeably.

For Ottawa specifically, winter scheduling matters. Green Glue is a viscoelastic compound that needs temperatures above 10°C to cure properly. If you are adding drywall to an unheated garage, basement, or addition during a January cold snap, temporary heating is not optional — it is required for the product to work as intended. Most experienced Ottawa contractors will flag this during the quoting process, but it is worth asking directly.

A few practical things to watch for. First, adding a second drywall layer increases wall thickness by roughly 5/8 of an inch, which means door frames, window casings, and electrical boxes may need to be extended — budget an extra $100 to $300 per door or window in the affected area. Second, the acoustic caulk perimeter seal is not optional. Sound will find the gap between the new drywall and the floor, ceiling, or adjacent walls and bypass the entire assembly if those joints are not properly sealed. Third, this upgrade works best when the existing wall already has acoustic mineral wool insulation like Rockwool Safe'n'Sound in the cavity — if the cavity is empty or filled with standard fibreglass, the Green Glue layer will underperform.

Realistically, a double drywall plus Green Glue treatment on an existing wall can add 4 to 8 STC points to the assembly, depending on what is already there. That is meaningful improvement — enough to take a noisy shared wall in a Centretown condo or a Barrhaven townhouse from frustrating to livable — but it is not a complete solution on its own if the existing wall has no decoupling or insulation.

For a project like this, it is worth having an experienced soundproofing contractor assess your existing wall construction before committing to a scope of work. Knowing what is already in the cavity changes the recommendation significantly, and a professional can tell you whether Green Glue alone will get you where you need to be or whether adding resilient channel or isolation clips would give you far better results for a modest additional investment. You can find soundproofing professionals serving the Ottawa area through the Ottawa Contractor Directory at justynrookcontracting.com/directory.