Installing sheets of plywood over attic insulation is a popular choice, especially in storage spaces. That said, insulation works by trapping hot air—so it needs extra space to expand and be effective, or you might reduce the energy efficiency of your home. 

It’s important that you never compress the insulation by installing flooring directly on top of it. In many houses, you’ll need to install a subfloor before putting plywood over insulation in your attic.

It’s best not to install a radiant barrier directly under insulation because it requires an air gap on at least one side to work properly. Instead, you should install the radiant barrier over your existing insulation to create an air space to reflect the radiant heat.

Rockwool insulation can last up to 100 years, but just how long this insulation lasts in your home depends on how well it's maintained. Poorly installed insulation may last only 30 years, so be sure to regularly inspect your home's insulation for water damage, settling, and pests to give your insulation the best chance of having a long lifespan.

Yes, insulating ductwork in a crawl space is a worthwhile investment, especially if you live in a colder climate or run your air conditioning for most of the year. Uninsulated ducts can lose up to 30% of their heating and cooling efficiency, which can significantly impact your electricity bill. The project is a relatively small investment and typically only takes a few hours. It's a particularly simple add-on if you are already hiring someone to insulate the entire crawl space. An added benefit is that insulated ducts put off less hot or cold air, making them less attractive to pests.