Mineral wool insulation

A roof system comprises, in sequence: a support structure; a mineral wool insulation panel 13 comprising a core of mineral fibres 22 and a non-woven veil 23 secured to its upper surface by a binder; and an overlying weatherproof membrane 14 secured to the mineral wool insulation panel by an adhesive. The adhesive penetrates through securing portions of the non-woven veil to provide an adhesive connection between the mineral fibres of the insulating panel and the weatherproof membrane, the securing portions make up between 5% and 95% of the surface area of the non-woven veil. Preferably the securing portions make up 15 to 85% or more preferably 20 to 80% of the surface area of the veil. The veil may comprise a filler which may be selected from calcium oxide, calcium hydroxide, aluminium hydroxide, clay, talk, magnesium silicate, and mixtures thereof. The non-woven veil may comprise glass fibres. The mineral wool panel may be a dual density panel with a higher density of surface layer fibres. Also included are claims to a mineral wool insulation panel and the use of a non-woven vale bound to a mineral wool layer.