How to Seal a Crawl Space

Whether you want to protect your house from insects and rodents, or you want to keep it extra insulated and prevent heat from escaping in the winter, sealing a crawlspace can be extremely beneficial. Properly sealing a crawlspace can be difficult to do, but with some handy knowledge and a step-by-step guide, you'll be able to completely seal your crawlspace with ease.

Examine your crawlspace from both the inside and outside and find all holes and entrances into the space. If your crawlspace is reasonably dark, going inside, turning off the light and looking for sunlight coming in from outside is a great way to do this. Seal the holes with expanding foam or caulk. Also look for any places where wires or pipes are running from the crawlspace into your home, or outside, as these are ideal entrances for insects and rodents.

Place weatherstripping around the doors that lead into your crawlspace. You want to make as airtight of a seal as possible, and you may have to place weatherstripping on both the edges of the door and the door frame. If the door is very old or not very thick, you should replace it with a thick door made out of heavy-duty wood or metal.

Lay down plastic sheeting in your crawlspace if you have a dirt or gravel floor. This will help keep moisture from the ground from seeping into your crawlspace and forming mold. You might also consider installing a small dehumidifier that you can periodically turn on to help reduce moisture content, since there will be no airflow once you finish sealing the crawlspace.

Once the crawlspace has been properly sealed, consider applying insulation to help increase energy efficiency and add an extra layer of sealant to the area. Insulation can be applied to the ceiling and walls of the crawlspace and cut to fit around pipes, wires and other obstructions.

Things You Will Need

  • Expanding foam or caulk
  • Weatherstripping
  • Plastic sheeting
  • Insulation


  • If you are unable to completely seal your crawlspace in one or more areas, you may want to place mousetraps near the entrances, in case any rodents find their way in. Sometimes it can be difficult or impossible to completely seal your crawlspace, and taking preventative measures against intruders is a wise move.

About the Author

Margaret Worthington has been writing and editing since 2001. Her work includes editorials and articles for a college newspaper, toy articles for Hasbro, copy-editing a romance novel and rewriting a publication for "GreenBlue." Worthington holds an Associate of Arts in English and journalism from Piedmont Virginia Community College and is pursuing a Bachelor of Arts in English and journalism from the University of Virginia.