Waterproofing Area Calculator (Bath, Terrace & Cost)
Estimate waterproofed floor and dado wall area, liquid coats, membrane rolls, and material budget for bathrooms and terraces in Nepal.
Floor 4.50 m² · walls 10.32 m² · terrace 0.00 m² · gross 14.82 m² before waste. Confirm product coverage and joint details on site.
How this works
Net waterproofing area combines floors, dado walls, and optional terrace:
floor = L × W
walls = 2 × (L + W) × dado height
net = (floor + walls + terrace) × (1 + waste%)
litres = net × coats × L per m² per coat
rolls = ceil(net / roll coverage)Worked example
A 2.5 × 1.8 m bath with 1.2 m dado, 10% waste, 2 coats at 0.5 L/m²:
- Floor 4.5 m² + walls ≈ 10.3 m² → gross ≈ 14.8 m²
- Net ≈ 16.3 m² → liquid ≈ 16.3 L → membrane rolls by coverage
Sources
- Coat counts and coverage follow product datasheets; always detail joints, drains, and upstands per manufacturer and designer.
FAQ
How do I calculate waterproofing area for a bathroom in Nepal?
Measure the floor length and width, then add the four walls up to the waterproofed height (often 1.0–1.5 m dado, full height in showers). Multiply floor and wall areas, add waste for corners and upstands (typically 8–15%), and use that net area for membrane rolls or liquid coats. This calculator does that arithmetic for bathrooms, wet kitchens, and terraces.
How many coats of liquid waterproofing do I need?
Follow the product datasheet. Many cementitious or acrylic systems specify two coats on floors and walls, sometimes a third on terraces or high-risk joints. Enter the coat count and the stated litres per square metre per coat to estimate total liquid. Always prime and detail joints as the manufacturer requires — quantity alone does not make a system waterproof.
Should I waterproof the terrace as well as bathrooms?
Yes, if the terrace is open to weather or sits above living space. Use the terrace fields for open-to-sky slabs. Terrace systems often need more coats, protection screed, and proper slope to drains. Pair this estimate with the tile or screeding calculators if you are finishing the surface after waterproofing.
Does this include labour and protection screed cost?
The optional cost field is a material budget per square metre (membrane or liquid + accessories as you define it). Labour, screed, tiles, and drain hardware are separate. Enter a dealer quote for materials only, or a full installed rate if you have a contractor lump sum per m².
What waste percentage should I use?
For simple rectangular rooms, 8–10% is common. Use 12–15% for irregular shapes, many floor drains, or membrane systems with large overlaps. Over-ordering a little is cheaper than a mid-job shortage on a wet-area package.