Abstract: The brick lining of a furnace or other high temperature enclosure is veneered by adhesively securing to the brick lining 10 blocks 11 of ceramic fiber material that have been made by a vacuum casting process and have been pre-fired prior to installation. An undercut rabbet 13 may be provided along the periphery of the cold face of the blocks to provide an additional key between the adhesive and the blocks. A jointing layer 14 of a resilient ceramic fiber felt is disposed between the side faces of adjoining blocks.