Pre-mixed powder mortar for making single-layer and single-product macroporous dehumidifying plasters, cement-free, composed of pure natural hydraulic lime (NHL 3.5 and NHL 5), Eco-Pozzolan, natural sands, recycled materials, light aggregates and special additives, with very low emission of volatile organic compounds. Indicated for the renovation of existing masonry, also of historical value, subject to rising damp. Product resistant to acid rain, the leaching action of rainwater, the alkali-aggregate reaction and soluble salts.