How to Install Basement Posts

Determine where to place the basement posts. Often support posts are set between existing posts in the center of the room. Posts can also be set underneath walls of the floor overhead to provide additional support. Both the ceiling support beam and floor should be in good condition in the locations you choose. The ceiling beam overhead should be solid and not show any signs of rot. The cement floor must have no cracks or signs of damage.

Measure the distance from the ceiling support beam to the floor. Subtract the amount recommended by the jack post’s manufacturer for the thread rod and top plate.

Cut the jack post support tube to the correct length, if necessary, using a circular saw. Remember to remove the amount you subtracted in Step 2 for the thread rod and top plate.

Position the bottom plate of the basement post under the support beam. Mark the location of the holes in the plate and set the plate aside. Drill holes in the concrete with a masonry drill bit that is the size specified by the post’s manufacturer at least 1/4 inch deeper than the lag bolts that come with the post’s assembly kit. Place the anchors into the hole and tighten each one two or three turns to expand them against the walls of the holes. Set the bottom plate over the holes in the concrete floor. Insert the lag bolts into the anchors and tighten them three to five turns with an adjustable wrench.

Set the basement post support tube into the base plate. Place the thread rod and top plate cap on the top of the post.

Hold a carpenter’s level against the side of the post to ensure the post is straight up and down. Extend the thread rod, using its adjustable hex nut, until the post is tight against the ceiling support beam. Mark where to drill holes for the top plate on the support beam. Insert lag bolts into the top plate and into the holes you drilled into the support beam. Tighten the bolts with an adjustable wrench.