Lime render and other Unilit natural hydraulic lime products

For more than 22 years, Telling Lime has provided solutions in restoration with our Unilit range of natural hydraulic lime mortars, lime render, grouts and decorative finishes. These combine the characteristics of porosity, adhesion and flexibility with modern day demands for consistency, ease of application and ‘non-synthetic’ stucco effect render.

Natural hydraulic lime products have the following characteristics:

  • Replication of the qualities of historic lime mortars assures their compatibility with natural mineral & lime mortar backgrounds
  • Conservation works can be continuous during the winter months with limited protection required
  • Resilience to flooding both in construction & remedy
  • Mortars that do not leech free lime deposits on to the mortar face
  • Tolerance of damp & salts transfer during setting without detriment to performance
  • Works are completed more economically without specialist skills
  • Mortars are never harder than the substrate to which they are applied
  • Moisture is extracted naturally & without time limit from masonry backgrounds
  • Lime bonding bridge coats ensure adhesion & compatibility for façade upgrading, negating the need to remove sound renders

Whilst harmful CO2 emissions occur during the production of both cement and lime, lime mortars are burnt at a temperature of 900ºC and cement at >1450ºC. A study of the lime cycle demonstrates that as much as 60% of CO2 created in the production is retained during the carbonation/setting process of hydraulic lime.

Natural hydraulic lime is suited for restoration and new build to promote traditional expansion joint free construction. Lime mortars allow the structure to move as individual elements rather than as a mass. External lime render, which provides a superb decorative finish for renovations and conversions, offers extremely high levels of flexibilty and durability. Unilit hydraulic lime products conform to the European Standard ENV-4951, NHL 2-3.5 and 5.0 for natural hydraulic lime.

Unilit hydraulic lime mortars are porous and allow the background to breathe and stabilise. A comprehensive range of products has been formulated to meet particular requirements. Unilit 20 is an insulating plaster that eradicates condensation and thermal shock on buildings of architectural or historical importance. Unilit 30 is suitable for salts containment applications such as in cellars and against rising damp.

Building and masonry mortars are supplied in various blends for new building in brick and stone and as a hydrate for blending with local sands, pre-bagged or pre-blended with limestone sand of an appropriate grade. Unilit grouts and mortars are suitable for stabilisation and consolidation works matching the physical and mechanical properties of the original construction.

Insulated Render
In new construction, the demand for a rendered insulated cladding system that is sustainable of source and made from recycled materials has led to the development of the Limetics system using Foamglas®, a 66% recycled cellular glass, and our hydraulic lime mortars. Inert, waterproof, non-combustible and highly resistant to impact, the system is particularly suited for schools and public buildings.

Recycled Encapsulated Energy
The thermal upgrading of solid wall structures and heritage buildings of historic importance creates unsurpassed challenges since overcladding is seldom an option. The only intelligent method of improving the thermal performance of the external walls of these buildings – largely constructed in lime mortar – is to insulate internally, but the natural “breathability” and through wall performance must be fully evaluated since:

  • Impermeable insulation mediums can lead to severe interstitial condensation
  • The outer surfaces of the building can become cold & damp & thereby subject to accelerated & aggressive weather attack
  • Moisture trapped within the shell of the building can cause mildew & fungal growth
  • Synthetic & impermeable plasters, linings, coatings & decoration are all potential contributors to fabric damage
  • Modern day insulation materials are a barrier to heat transfer, whereas wood fibre & other natural mineral slabs perform more like a storage radiator

Hydraulic Lime Floor Screeds, Concrete & Bonding Layers
Unilit offers lime concrete, wearing screeds, bedding and pointing mortars for stone and tiles. These can be laid without expansion or slip joints and prevents differential movement between the floor screed and the walls of lime built structures.

Application without a DPM will allow the floor to “breathe” with moisture from beneath the screed escaping as a vapour.

TECHNOpor® is a glass foam granulate (glass foam gravel) that is the ecological alternative for insulation to building floors. It is a lightweight, breathable aggregate made from recycled glass for use as a load bearing hardcore. It has a superior Lambda value to alternative methods requiring a reduced thickness to achieve the same thermal performance.

TECHNOpor® Perimeter 50 has a Lambda thermal performance of around 0.08. It is stable and load bearing with an exceptional compressive strength of approximately 500kN/m². The granule sizes are 30-50mm compacted by a vibrating plate.

When used in conjunction with underfloor heating, TECHNOpor® improves stability and ensures an open pore structure with a low coefficient of thermal expansion, thereby enhancing the storage of heat.

Lime Paints & Finishes
A comprehensive range of finishes is available in a choice of textures and colours to maintain the compatibility and porosity of the background.

Finishes include the Corical range of lime paints, lime washes, simulated marble coatings, granular aggregate finishes and roughcasts.

Telling provides a RIBA accredited CPD presentation for specifiers who wish to increase their knowledge in lime mortar technology.