Insulation lifespan and maintenance is an important consideration when choosing insulation materials. Long-lasting and durable insulation offers greater R-value, reduced energy costs and comfort over the lifetime of a building.
Regular inspections, prompt repairs and proper moisture control measures are key to maximizing insulation lifespan. Discover how different types of insulation last and how to maintain them for optimal performance.
How Long Will My Insulation Last?
A home’s insulation is a significant investment and homeowners want to know that it will last. However, the lifespan of insulation varies depending on materials and maintenance levels.
For example, fiberglass insulation in batt form can last 80 to 100 years if undamaged but it will start to degrade from around the 15-year mark and should be checked for deterioration at that time. This is because air movement causes the insulator to shift, which exposes areas where heat can escape or sneak into a home.
Other types of insulation such as cellulose, mineral wool and spray foam insulation can last decades as long as they are kept free from damage and moisture problems. Regular visual inspections of insulation should be conducted and any issues identified, including damage caused by pest infestation and moisture issues, should be addressed promptly to avoid further deterioration and maintain energy efficiency in your home.
Some common issues that shorten insulation lifespan include high humidity, mold and mildew growth, fire damage and smoke residue, and harsh weather conditions. It’s important to note that some problems may not affect the overall longevity of insulation but will impact its effectiveness, resulting in a lower return on your investment.
Fiberglass
Fiberglass insulation in the form of blankets, rolls, or loose-fill material typically lasts for anywhere from 80 to 100 years. It doesn’t degrade on its own unless it is exposed to moisture or becomes contaminated with rodent feces. However, bits may start to fall off fiberglass batts after 15 to 20 years so it’s best to schedule an inspection if you think your home’s insulation is getting old.
The fiberglass production process requires a number of raw materials, such as soda ash, alumina, borax, silica, and limestone. These materials are obtained through mining, which often uses geothermal, mechanical, or chemical energy to run the machinery involved in harvesting the resources (Mazor). To offset this, some fiberglass manufacturers use recycled glass material to help reduce the amount of energy used in manufacturing new fiberglass insulation.
Once the fiberglass insulation is blown into attics, crawl spaces, or stud walls, it will not degrade as long as it is maintained properly. It is also less likely to require removal compared to other types of insulation, such as cellulose, mineral wool, or spray foam insulation.
Cellulose
Cellulose insulation, made from recycled paper products such as newspapers and cardboard, is a loose-fill option that can be blown into open attics or enclosed wall cavities. It can be installed in new construction or as a retrofit in existing walls. Unlike fiberglass batts, which require that interior trim be removed to fit penetrations and corners, cellulose can be blown into wall or cathedral roof cavities from the inside without disturbing existing framing.
It is available in two forms: dry and damp. The latter is installed using a machine that blows the fiber while applying a mist of water from the spray nozzle to provide a permanent bond with the wall. The amount of water is adjusted to establish an important balance — it must be moist enough to stick to the wall, but not so wet that it causes moisture problems.
The process is quick and efficient, requiring less labor than other options like fiberglass batts, and cellulose can achieve the same R-value as other insulation materials. However, wet cellulose can lose its fire retardant treatment and must be discarded, so it’s a good idea to have a vapor barrier in place before installing this insulation.
Mineral Wool
Mineral wool insulation can last several decades, depending on climate conditions and maintenance. The material is naturally incombustible and does not require fire-retardant chemicals that can pose a health risk. It is also effective against noise pollution due to its structure and composition.
It is easy to install, fitting the stud cavity voids perfectly. Its rigidity also makes it easier to cut accurately, unlike fiberglass batts which are floppy and difficult to trim around outlets and other obstructions. Mineral wool is also water resistant, staying intact when wet. Fiberglass and cellulose, on the other hand, droop or clump up when wet and lose their insulating value.
The material is environmentally friendly and contains recycled materials, including molten rock (basalt or diabase) and spun slag—a byproduct of smelting metal. It is also safer to handle and use than fiberglass, which requires fire-retardant chemicals to produce. It is not classified as carcinogenic to humans and provides an R-value of about 23 per inch in a 2×6 wall, compared with R-19 for fiberglass batts and about R-6 for blown-in cellulose.
Spray Foam
Spray foam insulation, as well as cellulose and mineral wool insulation, are among the longest-lasting home insulation options available. According to the International Association of Certified Home Inspectors, these types of insulation last for more than 80 years.
The lifespan of these insulation materials is dependent on environmental conditions. Fiberglass batts and cellulose can settle over time, so these products must be regularly raked or topped up to ensure that they maintain their expected R-value. Spray foam, on the other hand, is an airtight barrier that does not settle.
Unlike fiberglass, spray foam insulation can withstand a range of temperatures and can resist moisture build-up, mold and mildew. This makes it a great option for North Carolina homes that are often plagued by humidity.
Working with spray foam requires specialized equipment that can be expensive to purchase and maintain. However, by following manufacturer recommendations for daily inspections and cleaning of guns and proportioners, spray foam insulation can be expected to last a lifetime. For some homeowners, the energy savings achieved with this type of insulation may even be enough to qualify for green certification.