Reflective foil insulation, while effective in certain applications, has several notable disadvantages. Its primary limitation is that it only works effectively when facing an open air space, as it relies on reflecting radiant heat. If installed incorrectly or compressed, its performance drops significantly. It offers little to no resistance to conductive heat flow on its own, so it is often less effective in very cold climates where conductive and convective heat loss dominate. Foil insulation can also be prone to condensation issues if not paired with proper vapor barriers, potentially leading to mold or material degradation. Furthermore, it is susceptible to dust accumulation, which can reduce its reflectivity over time. For these reasons, it is often best used as part of a hybrid insulation system rather than a standalone solution.

Reflective insulation is generally considered a cost-effective option compared to many traditional bulk insulation materials like fiberglass or spray foam. The material itself, often aluminum foil laminated to paper or plastic, is relatively inexpensive to manufacture. However, the total installed cost can vary based on the specific product, the complexity of the installation, and whether it is used alone or as part of a hybrid system. For radiant heat control in attics, walls, or crawlspaces, its performance per dollar can be excellent, particularly in hot climates where blocking radiant heat is a priority. While not always the cheapest upfront material, its durability and effectiveness at reducing cooling costs often provide a strong return on investment over time.

Reflective insulation, often using materials like aluminum foil, can be worth it in specific applications but is not a universal solution. Its primary function is to radiant heat transfer, making it highly effective in attics, garages, and metal buildings where the primary heat gain or loss is through radiation. It works best when facing an air space and is installed correctly. However, for most residential walls and ceilings, traditional bulk insulation like fiberglass or cellulose is more effective at stopping conductive heat flow. The value depends on your climate, existing insulation, and the specific area being insulated. A professional energy audit is the best way to determine if reflective insulation is a cost-effective addition to your home.

People are removing spray foam insulation primarily due to improper installation, which can lead to significant problems. If not mixed or applied correctly by a certified professional, the foam can fail to cure fully. This off-gassing can create persistent, strong chemical odors and potentially degrade indoor air quality. In some cases, the uncured material can even damage roof decks or structural wood by trapping moisture, leading to rot. Removal becomes necessary to eliminate health concerns, stop property damage, and address comfort issues like drafts that occur if the foam has shrunk or pulled away from framing. It is a complex and costly process that underscores the critical importance of hiring highly qualified installers.