To add vertical vents to a brick crawl space, pick locations that are similar to existing vents. Use a concrete saw to carefully cut the horizontal mortar joints. The bricks will be reused so try not to damage them, however, some will need to be cut to square up the new vents. Then take out the old mortar, and mix up some new mortar that you will spread onto the bottom and the end piece of each brick as it is put into place. Make sure the mortar joints are even and clean before they dry. Finally, cover the brick edges on the bottom with a sculptured layer of mortar before putting the vertical bricks in place. This will create a kind of vertical louver. And there you have a vertical crawl space vent.
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How to Add Brick Foundation Vents to Crawl Space – Home Improvement – Today’s Homeowner