FL4520 is a black preformed, elastic self adhesive expanding tape seal. Sealing between the foam and joint surfaces is achieved through a combination of the pressure sensitive adhesive impregnation and the back pressure of the expanding foam. Moisture adaptive membranes adapt their water vapour permeability to the humidity stress. An increased ambient air humidity causes the diffusion resistance to also increase. FL4520 is suitable to be used as a water, vapour, air, sound and dust seal in expansion/contraction joints or in static gasket-type joints such as sills or mechanically fastened joints. With heavy rain tightness to 1050Pa in accordance with EN 1027, FL4520 meets all the requirements relating to an air tight and heavy rain tight sealing product. Fire resistant to DIN 4102 B1