No, skim coat plastering is generally not suitable for exterior walls. Skim coat plaster is primarily designed for interior applications. Exterior walls are exposed to various weather conditions, moisture, and other external factors that can affect the durability and performance of skim coat plaster. For exterior walls, it is recommended to use specific exterior-grade materials that are designed to withstand the elements and provide adequate protection. These materials are typically more durable and weather-resistant than skim coat plaster, ensuring the longevity and integrity of the exterior surfaces.