Abstract: Flexible base web of a construction covering comprises a main layer extending at least over the greatest part of the thickness of the web and is constituted of a non-woven mineral fiber mat containing predominantly discontinuous mineral fibers. Said mat contains further blend fibers. The mat is manufactured using a dry method by means of an air stream whereby said blend fibers have become blended inside the mat during the dry method forming of the mat. The portion of said blend fibers is greater in the proximity of one of the surfaces of the mat than in the middle due to subsequent needling of the mat.

Abstract: In the method for manufacturing a product in the form of a mat containing mineral fibers and a binding agent, the binding agent is mixed with the fibers before the formation of the product. The material used as the binding agent includes thermoplastic particles, such as fibers, a powder, or particles in a dispersion, which are supplied to the fibers being formed of melted mineral into the stream of air. The fibers and the binding agent are carried by a turbulent air flow, in which the heat contained in the melting mineral and the fibers forming therefrom are used for melting or softening thermoplastic particles into a state, in which they effect the binding of the fibers to each other.