Is unpainted stucco waterproof?
Three-coat stucco is the most common exterior cladding here in Southern California; properly installed, it's tough, durable, and attractive. But it's not waterproof. No matter how skilled the plasterer is, rain will get behind stucco. Can you leave stucco unpainted? The short answer is... yes, stucco can be left unpainted for a short period of time or forever! Most stucco systems (not EIFS) use cement based products in their base coats and in some cases in the finish coat too (traditional finishes) which are proven to last long periods of time.