Gypsum lath was an early substrate for plaster. Also, drywall (plasterboard) came into common use replacing lime plaster on wooden lath. Metal lath and plaster, properly laid, forms a reinforced partition wall. The clay plaster rough coat varied to cover the irregular lath. The new building was of timber, with a lath and plaster exterior and thatch roof. Repairing damaged lath and plaster walls is generally more economical than replacing it. Temporary triumphal arches made of lath and plaster were often erected for royal entries. Three coats of plaster are required when using metal lath. In 1936 US Gypsum trademarked ROCKLATH for their gypsum lath product. This lath and plaster technique became widely used. This is not necessary for gypsum lath, which relies on a chemical bond. Often, the plaster needs the repairs, and not the lath itself. There are several reasons that a plaster and lath wall may fail. Split lath was nailed with square cut lath nails, one into each framing member. Types include expanded-metal lath, woven-wire lath, and welded-wire lath.