I want to build onto an existing single storey building that has strip foundations. What are the options to beef up the existing foundations?

Options for beefing up the foundations of an existing single storey building are:

1.underpin the existing foundations

2. build a steel frame to support the upper storey; this will require the addition of pad foundations to support the framework

In both cases, you will need structural engineers’ calculations to prove the strengthened foundations will be adequate for the extension.