Abstract: A pile weatherstrip has an elongate base strip carrying a pile of thermoplastic fibres. A zone is formed adjacent the base of the fibres fused together and compressed to reduce their width. This provides a comparatively smooth and narrow zone that does not snag on the flanges of a carrier as the pile weatherstrip is inserted into the carrier. The zone can be produced by passing the weatherstrip through a nip formed by heated rollers. In an alternative embodiment, the fibres are fused together for their whole height. This has the additional advantage of providing an air-impervious barrier.