How to Replace a Crawl Space Vent

Crawl space vents are installed to provide proper ventilation under the structure of a house that doesn't have a basement. Often, the perimeter walls of homes with crawl space construction use masonry. At regular intervals along the crawl space, adjustable screened vents are installed that are operable from the exterior of the home. If a vent is removed, damaged or simply missing, it is important to replace it quickly to prevent animals from accessing your crawl space.

  1. Remove the mortar that holds the vents in place. Use a hammer, masonry chisel and pry bar as necessary. Wear safety glasses and gloves. Clean up your edges.

  2. Measure your vent opening using a tape measure. Make sure that the faceplate of the vent that you purchase overlaps the opening on all sides by at least 1/4 inch. Prefit your vent to make sure that it fits flush to your foundation.

  3. Apply a thick bead of silicone along the back of the faceplate, and press the silicone into your foundation masonry. Make sure that the faceplate overlaps the opening on all sides and is straight and level.

  4. Thread a lock nut onto one threaded rod so that 3/4 inch of thread remains. Do this with both threaded rods.

  5. Pick up a threaded rod with the lock nut toward you. Reach inside the faceplate and locate a hole in the faceplate. Thread the nut and screw it toward you until the lock nut rests against the faceplate. Use a 7/16-inch wrench to tighten. Repeat on the other side with the second rod. You should have 5/8 inch of thread visible.

  6. Pick up the backer bar. Reach through the faceplate opening into the crawl space. Slide the backer bar so that it spans the masonry width of the vent opening from the back side. Slide the threaded rod through the backer bar, and use a wing nut. Do this with both rods, and tighten the wing nuts so that there is pressure pulling the faceplate into the silicone.

  7. Place your screen door insert or winter door insert in place over the threaded ends, and use a knurled nut to hold it on.

About the Author

F.R.R. Mallory has been published since 1996, writing books, short stories, articles and essays. She has worked as an architect, restored cars, designed clothing, renovated homes and makes crafts. She is a graduate of the University of California at Berkeley with bachelor's degrees in psychology and English. Her fiction short story "Black Ice" recently won a National Space Society contest.