In some places, we found that there had been previous attempts to stabilize and support the foundation, though this jack is only supporting the plywood directly above which will be a problem when the rest of the joists settle around it. However, using concrete blocks as a base is not as effective as a proper concrete footer, because it could potentially settle just like the foundation piers and walls. A proper concrete footer is installed several feet deep to a more solid plane to ensure long term stabilization and support.