Roundtower NHL 2 Coarse (Premix)
Roundtower NHL 2 Coarse is a ready-mixed lime mortar manufactured from Natural Hydraulic Lime (NHL 2) and coarse kiln-dried sand, blended in a controlled factory environment to provide a consistent, breathable mortar for traditional masonry and conservation work. Supplied in a pre-blended 2:5 lime-to-sand ratio, it eliminates on-site batching while maintaining the vapour permeability, flexibility, and compatibility associated with NHL 2 mortars.
Designed for bedding, pointing, and coarse render coats, NHL 2 Coarse is particularly suited to softer masonry, historic buildings, solid-wall construction, and projects where moisture management and material compatibility are more important than achieving high compressive strength. Being cement-free and vapour open, it allows traditional walls to dry naturally while reducing the risk of trapped moisture within the building fabric.
Technical Data
| Property | Value |
|---|---|
| Product Type | Ready-Mixed NHL 2 Lime Mortar |
| Binder | Natural Hydraulic Lime (NHL 2) |
| Mix Ratio | 2:5 (Lime : Sand) |
| Aggregate | 5mm Kiln-Dried Sand |
| Yield | Approx. 13.5 Litres per 25kg Bag |
| Render Coverage | Approx. 1.4m² @ 10mm Thickness |
| Brick Coverage | Approx. 25 Bricks per Bag |
| Water Addition | 4–5 Litres per 25kg Bag |
| Open Time | Minimum 8 Hours (Weather Dependent) |
| Standard | BS EN 998-1 & BS EN 998-2 |
| Packaging | 25kg Bags |
| Vapour Behaviour | Highly Breathable & Vapour Open |
Key Benefits
Ready-Mixed for Consistency
Factory blending ensures a consistent lime-to-sand ratio, eliminating variability associated with site mixing and helping deliver predictable performance across larger projects.
Breathable & Vapour Open
Allows moisture vapour to move naturally through the wall structure, helping traditional masonry dry out while reducing the risk of trapped damp and condensation.
Suitable for Softer Masonry
The feebly hydraulic NHL 2 binder develops a softer, more flexible mortar than stronger hydraulic limes or cement mortars, making it particularly suitable for:
- historic brickwork,
- rubble stone,
- soft stone masonry,
- and traditional solid-wall buildings.
Excellent Workability
Carefully selected sands and factory-controlled blending provide good workability, extended open time, and ease of application for both masonry and rendering applications.
Low Shrinkage Risk
The balanced mix design helps minimise shrinkage and reduces the risk of cracking when used as part of a breathable render or mortar system.
Cement-Free Construction
Contains no Portland cement, helping maintain compatibility with traditional building materials and breathable construction methods.
Typical Applications
- Pointing historic masonry
- Repointing stone walls
- Bedding soft brick and stone
- Coarse render base coats
- Traditional masonry repairs
- Conservation projects
- Breathable solid-wall construction
- Heritage restoration work
- Eco-building projects
Why Use NHL 2 Coarse?
Roundtower NHL 2 Coarse provides the same breathable, flexible characteristics as Roundtower NHL 2 but in a convenient ready-mixed format. It is particularly useful where consistency, ease of use, and reduced site mixing are priorities.
The coarse aggregate grading makes it especially suitable for:
- bedding masonry,
- pointing wider joints,
- and base render coats,
while the NHL 2 binder remains compatible with softer traditional masonry and conservation work.
For projects involving historic stonework, lime rendering, or traditional solid-wall construction, NHL 2 Coarse offers a practical way to achieve a reliable, breathable mortar without compromising material compatibility.
Typical Applications by Use
| Application | Recommended Use |
|---|---|
| Bedding Mortar | Soft brick, stone & rubble masonry |
| Pointing Mortar | Traditional stone & brickwork |
| Base Render Coat | Scratch & float coats |
| Conservation Work | Heritage & listed buildings |
| Solid Wall Construction | Breathable masonry systems |
Installation Overview
1. Surface Preparation
Substrates should be:
- clean,
- stable,
- free from dust,
- and appropriately dampened before application.
2. Mixing
Add approximately 4–5 litres of clean water per bag and mix thoroughly. Allow the mortar to stand briefly before remixing and application.
3. Application
Suitable for:
- bedding,
- pointing,
- masonry repairs,
- and coarse render coats.
4. Protection & Curing
Protect fresh work from:
- frost,
- heavy rain,
- rapid drying,
- and direct sunlight during curing.
5. Storage
Store dry, off the ground, and protected from moisture prior to use.
