Abstract: A method of increasing the volume of a portable building which has a tilt up roof extension and a tilt down floor extension by attaching temporary rams and brackets on the roof extension and floor extension to give favourable thrust angles and deploying the extensions. The roof extension is braced with diagonal cross braces. Thereafter the rams and brackets are removed and the perimeter of the extension is closed in with panels carried to the site inside the core of the building. When the building is to be transferred to another site, the procedure is reversed. The core of the building when collapsed is only 2.5 m wide which enables truck delivery on a highway.