Professional Wall Painting Estimation
How to account for wall texture and why 'two thin coats' are better than one thick one.
Area Analysis
Estimating paint starts with finding the "Net Area." You multiply the height and length of all walls in the room, but you must subtract the area occupied by windows ($~1.5\text{m}^2$ each) and doors ($~2\text{m}^2$ each) to avoid over-buying expensive paint.
The Coverage Formula
Surface Texture and Porosity:
- Fresh Plaster: Highly porous. It "drinks" paint. First-coat coverage might drop to $8\text{m}^2/\text{L}$. Always use a primer.
- Previously Painted: Non-porous. Coverage usually hits the maximum theoretical limit of $14\text{m}^2/\text{L}$.
- Textured Walls: Sand-finish or stucco walls have more actual surface area due to the "bumps." Increase your estimate by 15-20%.
Home Improvement Suite
- Fabric Yardage Calculator – Estimate materials for curtains and upholstery.
- Electricity Bill Calculator – Impact of new lighting on your bill.
- Water Bill Calculator – Monitor renovation-related water usage.
Frequently Asked Questions (FAQ)
Do I really need two coats?
Yes, especially if changing colors. The first coat seals the surface, while the second coat provides the true color depth and "sheen" (gloss level). If you skip the second coat, you often see "brush marks" or patchy spots when viewed in sunlight.
How much extra should I buy?
Always round up to the nearest standard can size (1L, 4L, 10L). It's better to have 500ml leftover for future "touch-ups" for scuffs and scratches than to run out and have to match a new batch color.