How to Install Floor Jacks for Sagging Floors

Wood Flooring

Floors begin to sag due to several issues, one of which is deteriorating old lumber. Other causes include home additions that have not been properly retrofitted for added weight or sinking concrete footings where current beam posts already exist. To fix the issue, adjust the existing beam post or add new adjustable posts. With a few specialized tools and materials, you can fix sagging floors without hiring a costly handyman or carpenter.

Things You'll Need

• Lumber for base plates
• Floor jacks
• Adjustable steel post
• Carpenters level
• String to check location of beam during adjustments

Instructions

1. Stack two 2x6 or 2x8 pieces of lumber to create a base plate where the floor jack will be used; the pieces of lumber should be a minimum 24 inches in length. Center the floor jack on the base plate under the beam. Use a hammer to place 16d nails around the floor jack to hold it in place. Some floor jacks feature holes on the base to allow for nailing.

2. Cut a 4x4 post to size so that is fits between the floor jack and beam. Adjust the floor jack so that the 4x4 post is snug between the lifting cylinder and the beam. Place a level flat on the surface of the 4x4 post to plumb it prior to making any adjustments to the beam.

3. Place an adjustable steel post in the desired position near the floor jack. Use clamps or nails to secure the top of the steel post to the beam that is being adjusted.

4. Adjust the beam with the floor jack. Pumping the hand lever will raise the beam to the desired level. If the beam is raised too high, turn the bleed nut slightly to lower the lifting cylinder to the floor jack. Be careful not to turn the bleed nut too fast which could cause damage or injury.

5. Adjust the steel post simultaneously with the floor jack. Turn couplings, which are located near the top and/or the bottom, by hand to accommodate the changes in beam height.

6. Hold the string from one end of beam and run it to the opposite end, and this will require the help of another person. While holding the string taut, check to see where the location of the beam is compared to the string. When the center of the beam is higher, lower the beam. When the center of the beam is lower than the taut string, raise the beam. The beam should be located within an eighth inch to the string throughout the entire length of the beam.

Tips & Warnings

• Use lumber that is free of defects such as warping, splitting, cracking or rotting.

References

• Sagging Floor Tips