Roundtower NHL 5 is a durable, high-strength Natural Hydraulic Lime, specifically formulated for high exposure applications such as limecrete floors, wall copings, foundations, and marine or damp environments.
Produced without additives and fully compliant with EN 459-1, Roundtower NHL 5 provides a reliable, eco-friendly solution for situations requiring greater strength and resistance to moisture or frost—all while supporting the principles of traditional and sustainable building.
Key Benefits
✅ High Strength – Suitable for structural masonry, flooring, and exposed exterior work.
✅ Highly Vapour Permeable – Allows walls and floors to "breathe", reducing risk of trapped moisture and decay.
✅ Resilient in Wet & Frost-Prone Environments – Ideal for marine exposure, basements, and copings.
✅ Natural & Cement-Free – Contains no synthetic additives; compatible with traditional and eco-building techniques.
✅ Self-Healing Properties – Free lime supports autogenous crack repair.
✅ Carbon-Conscious – Lime naturally reabsorbs part of the CO₂ released during production.
Applications
🔹 Limecrete Flooring & Screeds – Commonly used in breathable solid floor systems with Glapor foamed glass or recycled aggregates.
🔹 Wall Copings & Parapets – Robust binder for weather-exposed elements needing durability and breathability.
🔹 Retaining Walls & Foundations – Especially in areas subject to moisture or salt-laden conditions.
🔹 Marine & Coastal Repairs – Suitable for masonry exposed to wind-driven rain or splash zones.
🔹 Load-Bearing Masonry & Vaults – Where increased compressive strength is required without compromising vapour movement.
Technical Specifications
| Property | Value |
|---|---|
| Compressive Strength (28 days) | 6.2 MPa |
| Compressive Strength (7 days) | 3.54 MPa |
| Free Lime Content | 21.9% |
| Setting Time | 312 minutes |
| Fineness (90 µm) | 5.8% retained |
| Fineness (200 µm) | 1.0% retained |
| Expansion | 0.5 mm |
| Bulk Density | 0.775 g/cm³ |
| Real Density | 2.75 g/cm³ |
| Blaine Surface Area | 9,642 cm²/g |
| SO₃ Content | 1.48% |
| Standard Compliance | EN 459-1 (NHL 5) |
| Packaging | 25 kg bags (56 per pallet) |
Handling & Best Practice
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Apply in temperatures between 5°C and 30°C. We always advise following best practices for curing and protecting fresh lime mortars and renders from direct sunlight and wind using hessian sheeting, which acts as a barrier between the freshly applied lime and the environment.
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Protect during curing from frost, rain, and excessive sun.
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Use the minimum water required for a workable mix to reduce the risk of cracking. Dampen substrates the day before and prior to application, allowing the surface water to be reabsorbed. Avoid rapid drying due to high temperatures, direct sunlight or strong winds by covering and curing with a light water mist as necessary.
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Store in dry conditions, off the ground, and use within 12 months of production date.
Why Choose Roundtower NHL 5?
Roundtower NHL 5 is the lime binder of choice when strength, durability, and moisture resistance are essential. Whether you're building limecrete floors, stabilising historic sea walls, or detailing copings on a traditional building, this natural, breathable, and conservation-friendly binder offers the performance and reliability demanded by specialist contractors, architects, and conservation professionals.
