Underpinning job requires a professional contractor to do the work. If you are planning on expanding your home for another storey, it should be able to go through the regular process of getting permits for the construction wherein the underpinning task is included.
In order to have a successful underpinning job on your house, you need to hire first a professional contractor that can perform the task. This contractor should be able to provide you with a computation for the estimated expenses to be incurred and at the same time can also give you a proper layout plan on the job such as the length of time to finish the task, the materials needed, the steps in doing the task and where to start the work. A licensed and professional contractor should also be able to provide their own equipment and machineries to be used during the underpinning and it should always be supervised by a higher authority of their company.
Once the contractor is available, the budget that needs to be allotted on the job wherein the labor cost is also included and other projected expenses that you can tag as miscellaneous. The contractor should be the one to get the mandated permits in your place. These permits still fall on the construction category. You may also want to accompany the contractor. Permit such as building permit should always be visible in your place to avoid problems that may arise pertaining to permits.
The agreement between you and the contractor can possibly be in written form, too, so as to guarantee that there is existing work to be done. Asking for receipts and other documents is also you right as the owner or client. This way there is transparency between two parties. Lastly, always pay on time!