Roundtower NHL 3.5 White is a highly versatile, natural hydraulic lime binder, ideal for external plasterwork, rendering, pointing, and general masonry applications. With a clean, bright finish, it is especially suitable where a light or colour-matched mortar is required, such as on stonework, fair-faced brick, or decorative lime render finishes.
Produced to EN 459-1 standards, Roundtower NHL 3.5 White provides a balanced combination of strength, breathability, and workability, making it the preferred lime binder for new builds, solid wall construction, and restoration projects where slightly higher strength is needed compared to NHL 2.
Key Benefits
✅ High Whiteness – Ideal for colour-matched mortars and aesthetically sensitive work.
✅ Breathable & Vapour Open – Allows moisture to escape, reducing risk of trapped damp and condensation.
✅ Suitable for New Build & Restoration – Popular choice for lime rendering, pointing, and bedding.
✅ Strong Yet Flexible – Compressive strength of 5.5 MPa at 28 days, suitable for most external applications.
✅ Eco-Friendly Binder – Natural product with CO₂ reabsorption and low embodied carbon.
✅ Self-Healing Properties – Free lime content contributes to micro-crack sealing over time.
Applications
🔹 External Lime Renders & Base Coats – On stone, brick, and solid wall backgrounds.
🔹 Pointing & Bedding Mortars – Ideal for robust masonry work, including new builds and breathable wall construction.
🔹 Scratch & Float Coats in Lime Plastering – Particularly where a light finish colour is desired.
🔹 Mortars for Stone Matching – Suitable for projects where mortar tone is important.
🔹 Solid Wall Construction – Excellent for use in walls that require strength, breathability, and flexibility.
Technical Specifications
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Compressive Strength (28 days): 5.51 MPa
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Free Lime Content: 37.3%
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Whiteness (Y): 70–74
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Setting Time: ~1107 minutes (approx. 18 hours)
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Bulk Density: 0.604 g/cm³
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Real Density: 2.61 g/cm³
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Fineness (90 μm): 4% retained
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SO₃ Content: 1.42%
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Blaine Surface Area: 12,789 cm²/g
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Expansion: 0.1 mm
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Standard: EN 459-1 compliant (Natural Hydraulic Lime – NHL 3.5)
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Packaging: 25 kg paper bags (pallets of 49 or 56 bags)
Best Practice Guidelines
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Use the minimum amount of water needed for a workable mix. Excess water can compromise strength and setting.
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Protect from rain, frost, and direct sunlight during and after application.
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Apply in temperatures between 5°C and 30°C for optimal performance.
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Store dry, off the ground, and use within 12 months of production.
Why Choose Roundtower NHL 3.5 White?
Roundtower NHL 3.5 White is the go-to choice for tradespeople and conservation professionals looking for a clean, durable, breathable lime binder with added strength. Whether you’re plastering a new build, pointing a stone façade, or matching traditional mortars, this product offers consistency, purity, and long-term performance in both heritage and modern contexts.
