Inputs
Mix ratio: 1:4 (cement:sand) + plasticiser
Results
Enter your wall area then click Calculate.
TXTexas IBC / IRC (AHJ amendments)
References & Sources
Standards Cited
- ASTM C926 — Standard Specification for Application of Portland Cement-Based Plaster
Defines external render/stucco systems, coat thicknesses, and application methods - ASTM C1063 — Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster
Specification for substrate preparation and lath installation for stucco/render
Formulas Used
- Render volume:
volumeM3 = wallArea x (thickness x numberOfCoats / 1000)
Source: ASTM C926 - Dry product mass:
weightKg = (wallArea / coveragePerBagAt10mm) x (totalThicknessMm / 10) x 25kg x (1 + wastage/100)
Source: Representative manufacturer coverage data — This is dry product mass. Installed render volume is reported separately because wet/in-place density is not a bag-weight conversion. - Bags required:
bagsRequired = ceil((wallArea x totalThicknessMm/10 / coveragePerBag) x (1 + wastage/100))
Source: Representative manufacturer coverage data — Coverage per 25kg bag at 10mm: sand-cement 1.2 m2, lime 1.5 m2, polymer 1.3 m2, insulating 0.8 m2
Key Assumptions
- Dry product mass and bag count use the same representative 25kg-bag coverage assumptions — Representative manufacturer product data; verify the selected product datasheet
- Recommended mix ratios: sand-cement 1:4 + plasticiser, lime 1:1:6, polymer and insulating are pre-mixed — ASTM C926 / ASTM C1063
- Coverage per 25kg bag at 10mm thickness: sand-cement 1.2 m2, lime 1.5 m2, polymer 1.3 m2, insulating 0.8 m2 — Representative manufacturer product data; verify the selected product datasheet
- Typical wastage allowance of 10-15% for render — Industry standard practice