Monocouche Render Calculator — K Rend, Weber & Parex
Calculate monocouche render bags, mesh, bellcast beads, corner beads, stop beads and primer for K Rend, Weber and Parex render systems.
Wall & Render Details
Gross external wall area to be rendered
Total length along base of walls, for bellcast beads
Openings & Features
Each deducts 1.2 m²
Each deducts 1.8 m²
For corner bead calculation
Where render meets another material (not windows/doors)
Options
160g/m² alkali-resistant mesh with 100mm overlaps
Substrate primer (e.g. K Rend HP12) at ~5.5 m²/litre
Adds 10% extra for mixing and application losses
10% is standard for monocouche render
Price per 25kg bag for cost estimate
How We Calculate This
This calculator estimates all materials needed for a monocouche render system including render bags, reinforcing mesh, beads and primer. It supports K Rend Silicone TC30, Weber Monocouche and Parex Monorex GF — all of which have similar coverage rates.
How it calculates
Net wall area= Gross wall area − (Windows × 1.2 m²) − (Doors × 1.8 m²)
Render bags= Net area ÷ Coverage rate × Wastage factor. At 20mm thickness, all three render systems cover approximately 0.75 m² per 25kg bag (Weber Pral M: ~1 m²/bag at 15mm finished → ~0.75 m² at 20mm). Thinner application (15mm) increases coverage proportionally.
Coverage rates (per 25kg bag)
- At 15mm: ~1.0 m² per bag (Weber Pral M datasheet)
- At 20mm: ~0.75 m² per bag (standard)
- At 25mm: ~0.6 m² per bag
Accessories
- Mesh: 160g/m² alkali-resistant, factor of 1.15 for 100mm overlaps
- Bellcast beads: Along the base of all rendered walls (2.5m lengths)
- Corner beads: On all external corners, full building height (2.5m lengths)
- Stop beads: Around windows, doors and render terminations (2.5m lengths)
- Primer: ~5.5 m²/litre, applied to substrate before rendering
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Verify with your supplier.