In exterior stone paint projects, material shortages or excessive waste are common issues. In most cases, these problems are not caused by paint quality or workmanship, but by incorrect area calculation at the early planning stage. A frequent mistake is estimating material consumption based on building projection area or simplified wall dimensions rather than the real coating surface.

The application area of exterior stone paint must be calculated based on the actual exposed and unfolded surfaces that require coating. The first step is to measure the length and height of each exterior wall and sum all wall areas to obtain the total unfolded facade area. Next, deduct areas that clearly do not require coating, such as door and window openings, glass curtain walls, or other excluded zones. In practice, only the clear opening area of windows is usually deducted; if window frames or reveals are coated, the deduction should be adjusted accordingly.

Equally important is adding areas that are often overlooked but significantly affect material consumption. These include balconies, decorative moldings, cornices, columns, window sills, parapet walls, eaves, and all visible recessed or protruding surfaces. The final application area is calculated as:

Total unfolded wall area − non-coated areas + additional structural surfaces.

This result represents the net coating area. In real construction, a material loss allowance of 5%–15% should be considered. To ensure sufficient supply and smooth施工, adding approximately 10% to the calculated area is standard industry practice.