Egger D4 Joint and Joist Adhesive is a unique expanding glue which is up to 5 times stronger than nailed fixings. It is used for bonding the panels to the joist and within the tongue and groove joint as well as for sealing nail heads and adjacent areas. It is ideal for gap filling on uneven surfaces and joists and helps to eliminate squeaks that can happen with fully nailed floors. Once applied, it foams out of the board joint to prevent moisture ingress or stepping of joints.