When foundations settle it may be required to simply arrest and stabilize the condition at the current settled elevation, providing it has not been allowed to settle beyond a reasonable condition. Certainly, when laymen are capable of noticing a settlement conditon, this may be indicative of the problem going beyond this noticable condition and simply raising the structure back to a level should be considered. Generally, this demarcation of detection is in the range of 2 inches.
The process of underpinning involves the installation of piles to a stable zone below the foundation walls. The process we install is typically referred to as Jack-Down Piles. These are smart piles that structurally design themselves, as sections of interlocking steel pipes are individually hydraulically pressed down into the bearing soil using the weight of the foundation and superstructure as the resistance.
Depending on the diameter of the steel pipe sections and the condition of the ground, as well as spacing, there may be as many as 10 to 20 of these interlocking steel pipe sections installed, which is continued until there is a point of resistance where the foundation shows signs of wanting to lift. If only stabilization is required then this point of resistance would effectively provide for that condition. However, if raising the foundation is the objective then all the installed locations would be universally raised until the structure's level elevation has been reached.
Each pile is then filled with concrete and capped off, leaving the structure reliably supported on an underpinning system that could easily last lifetimes. This underpinning method is an excellent structural element when perserving historic properties. Be sure to contact Gunner Corp when experiencing foundation settlement concerns, foundation underpinning is only one possible remedial application within our arsenal.