At Roundtower Lime, we offer a comprehensive range of high-quality limes for use in heritage conservation, eco-friendly construction, and lime-based plasters and mortars. Whether you’re repointing a historic stone wall or applying a breathable lime render, our selection includes both Non-Hydraulic Lime (lime putty) and Natural Hydraulic Limes (NHL 2, NHL 3.5, and NHL 5)—each with its own set of performance benefits tailored to your application.
All our limes are carefully selected for purity, consistency, and compatibility with traditional and modern substrates. We stock top European brands and our own reliable Roundtower formulations, ensuring confidence and performance on-site.
Types of Lime We Supply
🔸 Non-Hydraulic Lime (Lime Putty)
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Also known as Fat Lime or Air Lime
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Sets slowly by absorbing carbon dioxide (carbonation)
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Offers superb workability and flexibility
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Ideal for interior plasters, limewash, lime mortars, and sensitive heritage restoration
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Remains soft and breathable—essential for delicate substrates
Natural Hydraulic Lime (NHL)
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Sets by hydraulic reaction with water and then through carbonation
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Comes in three strengths:
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NHL 2 – Soft and breathable, for interior plasters and soft masonry
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NHL 3.5 – Medium strength, for external renders and general use
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NHL 5 – High strength, for flooring (e.g. limecrete), seawalls, and exposed sites
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Offers faster set times and increased durability while remaining breathable
Why Choose Lime from Roundtower Lime?
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✅ Conservation-grade and CE certified
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✅ Extensive range: lime putty, NHL powders, and pre-mixed options
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✅ Technical support for mixes, applications, and site conditions
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✅ Used in national landmark projects across Ireland and the UK
Common Lime Applications
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Lime pointing for stone and brick
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Internal and external lime plasters
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Limecrete flooring systems
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Limewash and breathable paints
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Heritage and conservation masonry repair
Frequently Asked Questions (FAQs)
What’s the difference between Non-Hydraulic Lime and Natural Hydraulic Lime?
Non-Hydraulic Lime (lime putty) sets slowly through carbonation and remains soft and breathable. Natural Hydraulic Lime (NHL) sets faster through a chemical reaction with water, offering more strength while still allowing vapour permeability.
Which lime should I use for external rendering?
We typically recommend NHL 3.5 for external rendering unless the masonry is particularly soft—in which case NHL 2 is better suited.
Is lime compatible with modern building materials?
Lime is best used with natural, breathable materials like stone, brick, and can also be used on modern materials such as blockwork.
Why use lime instead of cement?
Lime is flexible, breathable, and sustainable. It prevents trapped moisture and allows solid walls to “breathe,” reducing condensation and long-term damage. It is also more forgiving on soft masonry.
Do you supply pre-mixed lime mortars or plasters?
Yes. We offer a full range of ready-mixed lime mortars, plasters, insulating plasters, and lime-based skims—made using NHL or matured lime putty, depending on the application.
