If you've spent much time paying attention to newer building techniques, then you know that spray foam is popular in many areas. Installers spray this type of insulation directly onto bare walls where it expands to fill the space between studs. Open-cell insulation can expand to many times its original size, requiring installers to shave it down before screwing in drywall.
This characteristic expansion is the reason for many of the benefits associated with spray-on insulation. As the foam expands, it fills cavities and minimizes the presence of air gaps in your wall. Ultimately, this means better thermal and sound insulating qualities. Unfortunately, it also means that its applications for existing walls may be limited.
The Expansion Problem
Most residential structures consist of 2x4s placed in the walls to act as studs. Insulation technicians spray foam onto the exterior portion of the wall, but it doesn't magically expand to fill the 4" gap between the exterior and interior walls. Instead, the foam expands, usually extending past the end of the studs.
This excess expansion is part of why foam insulation is so beneficial. Since the foam expands beyond the outer edges of the wall cavity, it's guaranteed to fill the space. Installers then shave off the excess foam, leaving a surface that will eventually sit flush against your drywall. This technique eliminates any air gaps in your wall, providing exceptional insulating qualities.
Unfortunately, this also means that spraying foam into existing walls is not usually possible. Not only does the applicator require direct access to the exterior wall surface, but the expansion will inevitably damage your existing drywall. As the foam expands, it will push on the inside of the drywall, most likely popping it off the studs.
Of course, you still have options if you want to use spray foam in your existing home. To add spray foam insulation to existing walls, you'll need to prepare them by removing the drywall and any fiberglass insulation already installed in the cavities. This process may be worthwhile if your existing insulation is old or water damaged, or you already need to remove your drywall for some other reason.
Additionally, spray foam can be helpful when renovating interior spaces. For example, you can add insulation to a new home theater room to provide sound reduction and better acoustic properties. In these cases, you may only need to remove drywall from one or two walls to insulate the space effectively.
Although there are additional challenges to using spray insulation with existing walls, it is possible with adequate preparations.
For more information, contact a business that provides open-cell foam insulation.