The general rule of thumb is to replace your attic insulation every 10-12 years. However, there are a few other factors you need to consider when making this decision. These include the level of insulation in your attic, the type of insulation, the climate you live in and how often your attic is used. If you have a high level of insulation in your attic, then you may not need to replace it as often. This is because the higher level of insulation will help to keep your attic cooler in the summer and warmer in the winter. The type of insulation you have will also play a role in how often it needs to be replaced. Fiberglass insulation, for example, will last longer than cellulose insulation.