Often overlooked by prospective buyers and builders alike, insulating walls and floors for sound during the construction phase of a building or home will provide a highly desirable level of comfort and privacy to building occupant an affordable price.
Attic ceilings, floors separating upper and lower living spaces, bathroom, bedroom and office partition walls are all examples where sound control is desirable. By planning and making a few simple changes to the construction plan and process, sound walls and floors are can be easily constructed and insulated by most individuals having a basic knowledge of building practices.
Before carrying out your project, it is important to understand that effective sound control requires 3 basic components - Drywall to provide mass and rigidity needed to deflect or reflect sound waves back into the room, resilient sound channel to break the pathway of sound traveling across the drywall and through structural elements and a fibrous sound insulation such as Therm-O-Light or Therm-O-Spray Insulation to absorb airborne sound within the cavity. Constructing a sound wall without one of these components will (in general) result in poor or unsatisfactory results.
One should also be aware that there are other construction details that effect performance such as framing and resilient channel spacing, insulation depth, type and spacing of the fasteners and the type and number of layers of drywall. Generally, maximizing framing, resilient channel and fastener spacing, applying multiple layers of high density drywall (fireboard) and maximizing the insulation thickness will result in better performance. However, many of these techniques cannot be employed due to code and engineering restrictions or they are cost prohibitive when considering the degree of performance improvement.
One final consideration before constructing a sound wall is flanking. Flanking is the bypassing of sound around an insulated assembly. This can happen in areas such as receptacle, switch and pot light openings, HVAC returns and supply ductwork and around sound walls located over uninsulated floor joist cavities. The most common solution to protect against flanking is to cover the uninsulated cavities with netting, secure it to the framing member with resilient sound channel and then inject Therm-O-Light insulation into the cavity. Another less common solution is to spray Therm-O-Spray insulation with an adhesive, into the cavity and then screed the insulation flush with the surface of the framing. This method is particularly effective for cold air returns located within a sound wall.
In the example below the return cavity is divided length ways into two cavities using standard HVAC panning. One side is then sprayed with Therm-O-Spray and screeded and the other fitted with resilient channel. The resilient channel also helps increase the effective depth of the chase ensuring adequate ventilation is maintained. Before insulating chases in this fashion remember to consult with an HVAC specialist in order to ensure minimum ventilation requirements are maintained.
No matter how challenging your sound insulating project might be, Therm-O-Spray and