Natural Hydraulic Lime (NHL) FAQs answer common questions about lime-based stucco systems, EcoMortar, breathability, curing time, strength grades, restoration use, and how NHL compares to cement and hydrated lime.
Natural Hydraulic Lime (NHL) is a 100% natural binder made from limestone that sets through a chemical reaction with water, providing breathability, flexibility, and strength without cement or additives. Mixed with sand, it forms a plaster or mortar suitable for walls, masonry, and lime-based stucco systems. Meoded offers Saint-Astier® NHL in different grades for sustainable, historic, and modern construction projects.
Natural Hydraulic Lime (NHL) is used for masonry, plastering, stucco, pointing, and restoration work. It is ideal for historic and modern construction because it offers strength, breathability, and flexibility. NHL is commonly used for exterior and interior walls, stone and brick masonry, lime stucco systems like EcoMortar, and moisture-sensitive structures.
NHL (Natural Hydraulic Lime) sets through a chemical reaction with water, allowing it to harden even in damp conditions. Hydrated lime (non-hydraulic lime) sets only by carbonation, reacting slowly with CO₂ from the air. NHL provides greater strength and durability, while hydrated lime is softer, more flexible, and better for plaster or limewash finishes.
Natural Hydraulic Lime (NHL) is a breathable, flexible binder made from limestone that sets slowly with water, allowing finishes to expand and contract without cracking. Cement sets rapidly and is rigid, making it more prone to cracks. NHL is ideal for masonry, restoration, and lime-based stucco systems like EcoMortar, offering durable, long-lasting finishes.
Yes, Natural Hydraulic Lime (NHL) is highly breathable. Its porous structure allows moisture vapor to pass through walls, helping regulate humidity and reduce condensation. This breathability protects masonry and finishes from trapped moisture, making NHL ideal for restoration projects, lime-based stucco systems like EcoMortar, and sustainable, long-lasting construction.
Natural Hydraulic Lime (NHL) is not fully waterproof, but it is water-resistant and highly durable. It can withstand rain and damp conditions without deteriorating, while remaining breathable to allow moisture vapor to escape.
These numbers indicate the strength and hydraulic set rate of Natural Hydraulic Lime. NHL 2 is the softest and slowest-setting, ideal for interior plasters and soft masonry. NHL 3.5 provides medium strength for general construction, including scratch, brown, and stucco coats. NHL 5 is the hardest and fastest-setting, suited for structural work and exposed exterior applications.
Yes, Natural Hydraulic Lime (NHL) is suitable for both interior and exterior use. Its breathability, flexibility, and water resistance make it ideal for interior plasters, masonry repair, lime-based stucco systems like EcoMortar, and exterior walls exposed to weather, ensuring durable, long-lasting finishes in all conditions.
Yes, premium Natural Hydraulic Limes, such as Saint-Astier NHL, are eco-friendly, contain zero VOCs and are made from 100% natural limestone with no synthetic additives. They are fully breathable, sustainable, and environmentally friendly, making them ideal for eco-conscious construction, masonry, plaster, and lime-based stucco systems.
For more information on breathable mineral materials and indoor air quality, see VOC safety standards.
Natural Hydraulic Lime (NHL) sets relatively quickly compared to non-hydraulic lime, but full curing takes longer. Initial set occurs within 12–48 hours depending on grade and conditions, while full carbonation and maximum strength can take several weeks. Proper curing ensures durable, breathable finishes for plasters, masonry, and lime-based stucco systems.
Yes, Natural Hydraulic Lime (NHL) is ideal for restoration and historic buildings. Its breathability, flexibility, and gentle curing process protect old masonry from cracking or trapped moisture. NHL allows walls to “breathe,” preserves structural integrity, and is compatible with traditional lime plasters, stone, brick masonry and limestone stucco systems like EcoMortar, making it perfect for heritage projects.
Natural Hydraulic Lime (NHL) based mortars are much less prone to cracking than cement-based products. Its flexibility and slow curing allow it to expand and contract with the substrate, accommodating movement without damage. When applied over a stable, properly prepared surface, NHL finishes maintain long-lasting, crack-resistant performance.
EcoMortar is a lime-based stucco system formulated with Saint-Astier Natural Hydraulic Lime (NHL) and sand. It provides a breathable, durable, and flexible finish for interior and exterior walls. EcoMortar combines the strength of hydraulic lime with traditional stucco techniques, offering long-lasting, sustainable, and aesthetically versatile finishes for modern and historic projects.
A lime-based stucco system, like EcoMortar, uses Natural Hydraulic Lime (NHL) instead of cement as the binder. It typically involves three coats—scratch, brown, and finish (stucco)—applied over a prepared substrate. Unlike rigid cement stucco, lime-based systems are breathable, flexible, and less prone to cracking, making them ideal for historic restoration and durable, sustainable construction.
Lime stucco, such as EcoMortar, is made with Natural Hydraulic Lime (NHL), making it breathable, flexible, and less prone to cracking. Cement stucco sets rigidly, dries quickly, and can trap moisture, leading to potential damage. Lime stucco is ideal for restoration, masonry, and long-lasting exterior or interior finishes.
Yes, EcoMortar is ideal for exterior applications. Made with Saint-Astier Natural Hydraulic Lime (NHL), it is durable, breathable, and flexible, allowing it to withstand weather and temperature changes. Its lime-based formulation reduces cracking and moisture issues, making it a long-lasting, sustainable choice for exterior stucco finishes.
Yes, EcoMortar is suitable for interior walls as well. Its breathable, flexible lime-based formulation allows it to regulate indoor humidity and create durable, elegant finishes. EcoMortar can be applied over masonry, brick, or plaster surfaces, providing a smooth or textured stucco finish that is both sustainable and aesthetically versatile.
Yes, lime stucco is naturally breathable, allowing moisture vapor to escape and reducing the risk of trapped moisture or mold. High-end lime stucco systems like EcoMortar retain this key property, delivering durable, flexible, and long-lasting interior and exterior finishes while supporting the health and longevity of masonry and plaster surfaces.
Yes, lime stucco naturally helps manage moisture. Its breathability allows walls to release trapped vapor, reducing condensation and the risk of mold growth. High-end lime stucco systems, such as EcoMortar, combine this property with flexibility and durability, protecting both interior and exterior surfaces while maintaining the integrity of masonry and plaster.
Lime stucco systems, such as EcoMortar, are typically applied in three coats: a scratch coat, a brown coat, and a finish coat. Unlike traditional cement stucco systems, no additional bonding coat or synthetic base (like Polybond or CI base) is needed over the brown coat, as the lime stucco naturally adheres and provides a durable, breathable finish.
Yes, lime stucco can be tinted or colored. Premium lime stucco systems, such as EcoMortar by Meoded, can be tinted or custom color-matched to virtually any shade. Because the color is integrated into the material, it creates a natural, consistent appearance that won’t peel or fade like surface-applied paints.
Yes, EcoMortar is fully compatible with historic and natural building systems. As a lime-based stucco, it offers breathability, flexibility, and vapor permeability similar to traditional lime mortars. These properties make it ideal for restoration, masonry preservation, and natural construction where cement-based systems could cause moisture damage.
Yes, lime stucco is more flexible than cement stucco. Its natural lime composition allows it to accommodate minor building movement without cracking, unlike rigid cement systems. This flexibility, combined with breathability, helps reduce stress, prevent trapped moisture, and extend the lifespan of the finish.
Lime-based stucco systems are highly durable when properly applied. They continue to harden over time, resist cracking through natural flexibility, and manage moisture through breathability. This combination helps prevent deterioration, making lime stucco a long-lasting exterior and interior finish that can perform for decades, even centuries, with proper maintenance.
Yes, lime stucco can be applied over existing stucco if the surface is stable, clean, and properly prepared. Loose or damaged areas must be repaired first, and proper priming or bonding preparation is essential to ensure adhesion and long-term performance of the lime stucco system.
Lime stucco should not be applied over non-breathable or unstable surfaces such as acrylic paints, elastomeric coatings, sealed masonry, metal, wood, or gypsum-based substrates. These materials trap moisture or move excessively, which can compromise adhesion and performance. Lime stucco systems perform best on mineral, breathable, and properly prepared substrates.
Yes, proper surface preparation is essential before applying lime stucco. Unlike cement systems, NHL-based lime stucco such as EcoMortar typically does not require synthetic bonding agents. Instead, a compatible mineral substrate or appropriate lath, along with proper dampening of the surface, ensures strong mechanical bonding and long-term performance.
Yes, NHL based stucco such as EcoMortar is well suited for straw bale construction. Its breathability allows moisture vapor to escape, helping protect the straw from rot and mold. Lime stucco’s flexibility and compatibility with natural substrates make it an ideal, time-tested finish for straw bale and other natural building systems.
Yes, lime stucco is highly recommended for coastal and humid climates. Its natural breathability allows moisture vapor to escape, reducing trapped moisture, mold, and salt-related damage. Unlike cement stucco, lime-based systems remain flexible and durable, making them one of the best-performing stucco options for high-humidity and coastal environments.
Choosing the right NHL lime depends on your application. NHL 2 is best for interior plasters and soft masonry, NHL 3.5 works for general construction and stucco systems like EcoMortar, and NHL 5 is suited for structural work or exposed exterior walls. Consider substrate, exposure, and desired finish when selecting a grade.
These Natural Hydraulic Lime (NHL) FAQs are designed to help homeowners, builders, and restoration professionals select the proper lime grade, understand curing requirements, and choose the right lime-based stucco system for long-term performance.
Natural Hydraulic Lime (NHL) FAQs are especially useful when selecting the proper lime grade for stucco, masonry, and historic preservation projects.