If you have crawl space vents that are difficult to open, or do not open at all, consider replacing them. While some builders argue that craw space vents are not necessary, most agree that if you do have vents you should be able to open and close them according to weather conditions. Crawl space vents also ensure that the area underneath the house does not become to moist and begin to mold.
When purchasing new crawl space vents, look for vents that allow you to open and shut them as necessary. Some larger vents will have an inset that you can remove, allowing you uninhibited access to the area underneath your house. You should also calculate the amount of vents your home should have: a home improvement center should be able to help you figure out the necessary vent square footage to adequately vent your home for your particular climate.
Step 1: Pry out the old crawl space vents. Start by removing any caulk used to seal the face of the vent to the exterior of the building. Then use a pry bar to pry the vent away from the wall. If it is difficult to use, you can use a cold chisel and hammer to remove some of the material holding the crawl space vent into place.
Step 2: Use a cold chisel to clean up the rough opening for the vent. Any caulk, mortar, or other debris should be removed and discarded. Measure the rough opening and purchase a crawl space vent for that space.
Step 3: If brick secure the crawl space vent, check the condition of the mortar around the rough opening. Mix and patch any areas that were removed or seem crumbly.
Step 4: Fit the new craw space vent into the rough opening. Apply mortar to the inside of the rough opening with a trowel, then slide the vent into place.
Step 5: Apply a bead of silicone caulk around the perimeter of the crawl space vent. This will prevent water from sliding between the exterior of the house and the crawl space vent.