Abstract: The present invention relates to multi-layered composite structures and to methods for the preparation thereof. The present multi-layered composite structures are light weight and capable of high load bearing making the present multi-layered composite structures especially suitable to be used as load bearing structures in, for example, automotive. Specifically, the present invention relates to methods comprising the steps of a) providing a mould for said multi-layered composite structure; b) layering said mould with two or more layers forming the outer surface of said multi-layered composite; c) filling said layered mould with a mixture comprised of non-expanded heat-expandable microspheres and closing said mould; and d) subjecting said closed mould to a temperature of 80° C. to 140° C. during 1 to 230 minutes thereby providing a relative pressure in said closed mould of 0.