Terrazzo and cocciopesto are ancient floor finishes that are gaining ground again today in both restoration projects and contemporary architecture. Both techniques combine beauty with sustainability and each tells their own story of tradition and craftsmanship.
Terrazzo is a timeless classic that dates back to the 15th century in Venice. This seamless floor owes its charm to the combination of elegance, character and robustness. Terrazzo was originally created when Venetian workers mixed scraps of marble granules with lime or Roman cement to create affordable, decorative floors. Today, Venetian terrazzo is still immensely popular because of its durable nature and aesthetic versatility. This floor consists of three main components:
- Binder: cement or lime
- Aggregate materials (such as broken bricks, marble granules, shells, etc.)
- Natural color pigments
Cocciopesto is one of the oldest floor types in the world and is considered the precursor to terrazzo. This technique originated in ancient Rome, around the 2nd century BC. In ancient Rome, they used slaked lime mixed with pozzolane as a binding agent where it was used as a durable and waterproof building material. The name refers to the method: 'coccio'means' shard ','pesto'is derived from' pestare ', Italian for crushing or stamping. Cocciopesto is therefore literally a ground brick mortar.
The binding agent past and present
The binding agent forms the basis of both terrazzo and cocciopesto floors. Originally, in ancient Rome and 15th-century Venice, people mainly worked with air lime (CL) or natural hydraulic lime (NHL), mixed with pozzolanic materials such as crushed brick or volcanic ash. These calcareous mortars were durable, permeable to vapour and were ideal for humid environments. With the rise of cement in the 19th century and later epoxy (1950), various variations of the original are available. Each with their pros and cons:
Cement-based terrazzo is strong and quick-curing. It offers a tight result, but is not vapour-permeable and can be more sensitive to hairline cracks, rising moisture and the presence of salts when temperature changes.
Epoxy terrazzo has an even higher compressive strength than cement-based terrazzo, is very easy to maintain and offers an ultra-thin finish with intense color options. On the other hand, it is not vapour-proof and is therefore less suitable for historic buildings or damp surfaces.
Lime-based terrazzo or cocciopesto on the other hand, offers an authentic, warm appearance with a vapour-proof structure. This solution is ideal for restoration projects or for those who consciously choose a sustainable and healthy living environment.
For those who want to build a terrazzo or cocciopesto floor in accordance with the rules of the art, choosing the right binding agent is essential. Natural hydraulic lime, Tradi 100 (NHL 5) by Saint-Astier offers a perfect balance between technical performance, ecological value and historical correctness. NHL 5 by Saint-Astier, a pure lime without additives or cement, is ideal for applications where strength, moisture regulation and sustainability must go hand in hand.
Specifically for cocciopesto and calcareous terrazzo, NHL 5 offers:
High mechanical load capacity
Tradi 100 (NHL 5) by Saint-Astier offers excellent compressive and flexural strength, making the binder particularly suitable for walkable applications such as floors. Thanks to its high mechanical performance, it effortlessly withstands daily stress, making it perfect for durable terrazzo or cocciopesto floors that are used intensively, both in private homes and in public areas.
Performance in humid environments
In applications where moisture plays a role, such as bathrooms, cellars or kitchens, NHL 5 is an excellent choice because of its hydraulic curing mechanism. This natural hydraulic lime can also harden by reacting with water instead of air, which ensures strong water resistance. This allows it to be used safely in humid environments without the risk of premature degradation or weakening of the structure.
Breathability and moisture regulation
In contrast to cement or epoxy, NHL 5 is vapour-proof as a binding agent. This breathable character allows moisture from the surface to evaporate naturally through the floor. This prevents condensation problems, mold, problems due to rising moisture and internal stresses. This feature makes NHL 5 ideal for renovations of older buildings with problems such as rising humidity or insufficient ventilation.
Resistance to sulphates and salts
An additional advantage of NHL 5 is its high resistance to chemical influences such as sulfates and salts, which are often present in historic buildings or coastal areas. Where cement-based mortars can degrade quickly here, an NHL 5-based floor remains durable and stable. This feature makes it a reliable choice for restorations and applications in more severe climatic or chemical conditions.
Practical processing and usage tips
For terrazzo or cocciopesto, a standard ratio of 400 kg NHL 5 per m³ aggregates apprehended. If you want to add pigments, this may amount to a maximum of 2% of the weight of the calcium binder (e.g. max. 8 kg pigment at 400 kg NHL 5).
Indicative mix:
- 400 kg NHL 5
- 650 L quartz sand (0–4 mm)
- 350 L marble aggregates (4–8 mm)
- 160–180 L water (depending on the moisture content of the aggregates)
A terrazzo or cocciopesto floor is usually installed in a thickness of 30 to 60 mm, depending on the granules. The larger the granules and the better the granulometric structure, the thicker you can work and the lower the risk of cracking.
Recommended aggregate types and sizes:
- 30–40% marble aggregates of 4–8 mm or larger (8–12 mm): the larger and more abundant the aggregates, the more character the floor will have after polishing.
- 60–70% fine quartz sand (0–4 mm): provides extra hardness, better workability and a more level surface.
- Optional: 5–15% extra-fine fraction (0–0.5 mm): to make the mortar denser, less porous and easier to polish.
User manual:
- Dry mixing: Start by thoroughly mixing NHL 5 with sand and aggregates (such as broken bricks, marble granules, shells...).
- Add water: Add water gradually until desired workability is reached. The mixture should not be too liquid.
- Pouring and compacting: Apply the mixture into the formwork and compact thoroughly to avoid air inclusions.
- Curing: NHL 5 hardens slowly, an average of 7 days per 10 mm layer thickness. Count on a curing time of 28 to 60 days, depending on thickness and weather conditions. Keep the surface moist for the first few days to prevent cracking.
- Sanding: Start sanding lightly when the surface is plastic but no longer wet. Then let it cure completely for a final finish.
Waterproofing treatment: It is possible to use terrazzo or cocciopesto as a shower floor, provided the surface is treated with an appropriate waterproofing product. An impregnation, wax, oil or another hydrophobic agent such as RC M060+ is recommended. This treatment makes the surface water-repellent without fully blocking vapour permeability. Regular reapplication is required to maintain effectiveness; annual inspection is recommended.
Underfloor heating: Underfloor heating is not an issue, but must be turned off during installation and curing to avoid rapid drying, cracks, lime carbonation and poor adhesion. Once fully dry and cured, heating can be restarted gradually, beginning at 15°C and increasing by 2–3°C per day to the normal operating temperature, in order to avoid thermal shock.
Additional tips:
- To prevent overly rapid drying (especially during the first week), it is advisable to temporarily cover the floor with a vapour-permeable cloth (e.g., building fabric, moist jute, etc.).
- For large surfaces (>25 m²) and especially when underfloor heating is present, it is wise to provide expansion joints.
Terrazzo and cocciopesto combine beauty, tradition and craftsmanship. Thanks to modern, nature-friendly products such as NHL 5 by Saint-Astier, these traditional techniques can now be used again sustainably, qualitatively and with respect for the original. Whether it's a prestigious restoration, a characterful home or a modern interpretation of a classic — these floors will impress for generations.
