plaster - a mixture of lime or gypsum with sand and water; hardens into a smooth solid; used to cover walls and ceilings

render - a substance similar to stucco but exclusively applied to masonry walls

adorn, decorate, grace, ornament, embellish, beautify - make more attractive by adding ornament, colour, etc.; "Decorate the room for the party"; "beautify yourself for the special day"

coat, surface - put a coat on; cover the surface of; furnish with a surface; "coat the cake with chocolate"