Three signs that you need crawl space insulation are drafts, high energy bills, and mold. Drafts can start in crawl spaces and cause hot or cold air to spread to the rest of your home through holes in the floors and walls. And even if your entire home is well-insulated, you can still feel an unchecked draft from your crawl space and in your utility bill. Uninsulated crawl spaces can let in air and moisture, and because they’re built directly on the ground and difficult to dry out, they are hotspots for mold and mildew.

In some areas, insulation companies require a special license, while some states only require them to hold general contractor licenses. Some municipalities may not mandate any license, although you should always ensure a contractor is fully insured. You can use Angi’s license lookup tool to confirm whether or not an insulation contractor you’re considering holds the necessary license for your area. You can also contact the company for information regarding licenses, certifications, and insurance.

Doubling the insulation in your home also doubles the R-value of said insulation. In other words, by adding more insulation, you can reduce the heat loss by half. Most homes benefit from increasing insulation. Older homes, in particular tend to have less insulation as is, so doubling your insulation could drastically reduce your energy bills, keep your home more comfortable, and take the strain off your HVAC system.

Insulating windows with plastic works, but it can be time-consuming, and the end results can—and often do—end up lacking in aesthetics. Window film and caulking your windows to make sure there are no drafts are two options that increase the energy efficiency of your home in a low-cost way. Plastic can be a good strategy while you consider alternatives.