What's the price to add damping compound between existing drywall layers without full tear-out?

Adding damping compound between drywall layers without full tear-out — the classic "peel and re-layer" approach — typically costs between $6 and $14 per square foot in Ottawa, or roughly $1,800 to $4,200 for a standard 10-by-12-foot wall (both sides). This technique involves applying a layer of Green Glue Noiseproofing Compound directly to the existing drywall surface, then screwing a new layer of 5/8-inch Type X drywall over top. It is one of the most cost-effective soundproofing upgrades available because it avoids the mess, disruption, and expense of tearing out existing walls.
The material costs are straightforward: Green Glue compound runs $15 to $22 per tube, and each tube covers approximately 32 square feet. For optimal performance, you should use two tubes per 4x8 sheet of drywall (one tube works but delivers noticeably less damping). A sheet of 5/8-inch Type X drywall costs $14 to $18. So for materials alone, you are looking at roughly $2.50 to $4.50 per square foot. Labour in Ottawa adds another $3.50 to $9.50 per square foot, depending on the complexity — factors like working around existing outlets, light switches, trim, and window casings all add time.
The results are genuinely impressive for such a non-invasive treatment. Adding Green Glue plus a second layer of 5/8-inch drywall to an existing wall typically improves the assembly's performance by 8 to 12 STC points. A standard single-layer drywall wall with fibreglass insulation (around STC 35) can jump to STC 43 to 47 with this treatment. That is the difference between hearing your neighbour's conversation clearly and hearing only a faint murmur.
There are a few important practical considerations. First, Green Glue needs temperatures above 10°C to cure properly, which matters during Ottawa's cold months if you are working in an unheated space like a garage or addition. Curing takes 7 to 30 days to reach full effectiveness, though you will notice improvement within days. Second, every electrical outlet and switch in the treated wall needs to be extended with box extenders (about $2 to $4 each) since you are adding roughly 5/8 inch of depth. Third, baseboards, crown moulding, and window casings will need to be removed and reinstalled, which adds to the labour cost. Finally, and this is critical, seal every edge and penetration with acoustic caulk — even one unsealed gap can reduce the benefit of the entire treatment by several STC points. This is a project that a handy homeowner could attempt, but professional installation ensures the damping compound is applied correctly and all edges are properly sealed. Ottawa Soundproofing's Sound IQ can help you understand whether this approach is sufficient for your particular noise problem or whether a more comprehensive solution is warranted.Looking for experienced contractors? The Ottawa Construction Network connects homeowners with qualified professionals:Justyn Rook ContractingJC CarpentryJaiko Cleaning ServicesSpeedy Pete's IncThe Next RenoView all contractors →