Types of Underpinning
There are three types of Underpinning methods which vary in permanence and cost depending on the property requirements:
1. Injection method (Temporary method - no warranty / no insurance / no engineering certification )
There are three types of Injections methods; Foam, Grout or Mud .
All Injections methods inject into the earth to help either raise or fill voids where required. These methods may often stop or slow the subsidence from reoccurring. As the method involves injecting into the unknown unstable ground, it cannot be guaranteed. The injection methods are not a permanent rectification and will most likely require your underpinning contractor to come back on a number of occasions. The injection methods will not be certified by a structural engineer. This injection method is commonly used on Non-structural structures; for example footpaths, factory floors, filling voids under residential floors, road way, bridge endings and rock anchors.
2. Concrete pile underpinning ( Permanent method )
Concrete pile underpinning will involve drilling in to the earth until rock is found or the suitable KPA is found. A structural engineer will supply a design for the concrete underpin and a geotechnical engineer will confirm the depth required. This method of concrete pile underpinning will be certified by a structural engineer and is permanent and will most likely not require ongoing works. This type of underpinning is used on structural buildings.
3. Screw pile Underpinning ( 50 year life span )
The method of screw piling involves drilling down to either gain greater depths and or to drill through water tables. A structural engineer will supply a design for the screw pile underpin and a geotechnical engineer will confirm the depth required. This method of screwpile underpinning will be certified by a structural engineer. This type of underpinning is permanent and will most likely not require ongoing works.
The limitations of screw piling is the greater size of machine needed to install the pile and the 50 year life span of the screw pile. This type of underpinning is used on structural buildings where it is possible for an excavator to gain access. It is mainly used to secure foundations on a new build and occasionally with the rectification of subsidence.
General Advice Warning.
The information on this web site does not take into account your personal situation. You should consider whether the information is appropriate to your needs, and where appropriate, seek professional advice from a REPQ registered Engineer's and seek independent legal advice from a construction lawyer with respect to your entitlements before claiming through body corporate and or insurance providers.