In present time, the achievement of a sustainable building industry is a major issue. This must to meet new requirements regarding the selection and rational use of raw materials and energy resources by controlled minimization of the total CO2 emissions as well as the requirements for the quality, reliability and functionality of building materials and structures for provision of optimal indoor climate For these reasons, more attention is given to natural materials as alternative to obtain the products with high mechanical and thermal insulation properties, but with less impact on the environment and human health due to their renewability and biodegradability. In this respect, the use of lignocellulose residues as reinforcements in composite materials is more appreciated and studied in the last time, due to their advantages comparing with synthetic fibres: low cost, nontoxic, biodegradable, abundant, low density and very good mechanical properties. In present study the composite materials based on natural additives (diatomite) and mineral oils matrix reinforced with agro-wastes and residues from industrial process of vegetal oil (sunflower oil) manufacturing are obtained in laboratory scale. These composite materials were evaluated regarding their thermal insulating and mechanical properties comparing with existing commercial petroleum based insulation materials.