External plastering refers to plasterwork done on exterior walls. There are several types of external plaster, including stucco and pebbledash. Stucco is made of lime, sand, and water and is applied in three coats - a scratch coat, brown coat, and final coat. Pebbledash, also called roughcast, is a rough form of plaster where small gravel or pebbles are thrown onto a wet coat of plaster. It helps insulate buildings. Both stucco and pebbledash have been used historically and continue to be used for their decorative and insulating properties on architectural projects.