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All of the components of a bonus room must be installed right in order for them to work well.
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By Brad Oberg
Today's homeowners constantly seem to be looking for more space, and bonus rooms provide it. Whether built as part of a new home or as a remodeling project years later, bonus rooms require the same care, skill, and construction quality as all other building features.
Builders and remodelers need a plan that considers how the bonus room affects the home’s overall safety, energy efficiency and thermal comfort, as well as the bonus room itself. This series of articles presents eight Best Practice strategies for proper design and construction of bonus rooms, from floor to walls to attic--even to the air in the room.
For detailed information and instructions about each component and other aspects of building a bonus room, just click on the article topic below.
- Floor Over Garage. The floor over an unconditioned garage space presents some unusual insulation challenge. The first one is safety of the room. All penetrations—in the floor, knee walls, or ceiling—into the bonus room should be carefully sealed with caulk or closed cell foam, as all of these spaces are connected to the garage.
- Knee Walls. Despite the common use of knee walls in attics, as well as in bonus rooms and mechanical rooms, knee walls are often improperly insulated.
- Cathedral Ceilings. The sloped portion of ceiling found in most bonus rooms presents another challenge to proper insulation. These areas are subjected to the same solar exposure as conventional attics but do not have the same available space as attics to provide for a larger volume of insulation, although the structural depth can be altered to provide additional space for insulation.
- Standard Attic. While this flat portion of the ceiling may vary in size depending on the size and design of the bonus room, it should be insulated in the same manner as a traditional attic space.
- End Wall. One of the two walls is typically adjacent to the conditioned space of the house and, therefore, is essentially an interior wall. At the other side of the bonus room, the end wall is simpler, and it should be constructed the same as an exterior wall.
- Careful Insulation. Insulate every component of a bonus room carefully to reduce energy loss and seal the insulated areas to prevent air infiltration through the walls. Without airtightness, the moisture in warm, humid air could pass into the assembly and condense on any surface with a colder temperature.
- Air Quality. Ensuring safe air quality by airsealing is essential. Cars, lawn mowers and other equipment and materials will emit poisonous carbon monoxide and other harmful vapors. Pressure balancing between the bonus room and the rest of the house is important to indoor air quality, too.
Correctly designing and constructing bonus rooms will help to ensure a safe, comfortable space for homeowners. It’s critical for site supervisors to understand that insulation, airsealing, equipment sizing, and indoor air quality are all components that need to be considered so that they can ensure that work on site is being implemented correctly. Taking care to properly select and install materials will ensure good performance throughout the home in the long term, thus boosting a builder’s reputation and preventing callbacks down the road.
Brad Oberg is co-founder and chief technology officer of IBACOS,a building-science company based in Pittsburgh. He has directed extensive research into the integration of ventilation strategies, residential ductwork design and performance, improved residential airtightness approaches, and durable construction approaches.
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