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Telling Lime Products - Breathable Insulated Lime Floors

Insulated Lime Floor - Screeds - TECHNOpor - Perimeter 50 - Thermal Improvement - Underfloor Heating

Unilit Insulated Lime Floor Solutions

Breathable lime floors are an effective and economic alternative to cement based and concrete floors, providing good insulation values and excellent compressive strength. Application of lime screeds with underfloor heating creates greater stability, open pore structure and extremely low coefficient of thermal expansion.

Unilit mortars remove the risk of thermal movement and thermal shock, producing a greater storage of heat within the floor when compared to cementitious screeds. Breathable insulated lime floors offer an alternative to cement concrete floors as well as providing good insulation values.

A lime floor is made up of three layers:

1. Free draining sub-base;

2. Lime concrete slab;

3. Lime screed which can contain underfloor heating.

Sub-bases consisting of TECHNOpor® Perimeter 50 foamed recycled glass reduce the risk of rising damp and offer an excellent thermal performance.

Unilit utilises a modern-day manufacturing process to create lime mortars with an early initial set that retains the traditional characteristics of flexibility, vapour permeability and a low salts content. The materials are easy to use by skilled masons or plasterers.

Unilit lime screeds can be waterproof, but remain permeable by ensuring the passage of moisture as a vapour between the floor and the interior. Rising damp can freely evaporate through the lime screed, preventing the build-up of a hydrostatic pressure within either the floor or the structure. The low salt content of the lime binder, as well as its permeability to water vapour, controls the risk of efflorescence (salts) after the finished screed or the tiled flooring has cured. Where stone, paving or tiles are then to be laid over the screed, the use of a Unilit bedding mortar will ensure the performance of the screed is maintained and the compatibility of the mortar with the stone.

Lime Floors - Advantages

Unilit natural hydraulic lime allows the laying of slabs and floor screeds without the requirement for expansion or slip joints. The application of Unilit screeds will also prevent differential movement between the floor screed and the walls of lime built buildings.

In new build construction, damp proof membranes are continuous under the floor and walls, but in refurbishment of old buildings, a DPM should be avoided because it can cause concentrations of moisture at wall junctions with an increased risk of rising damp.

By using lime as the binder in a floor slab or screed, the floor remains permeable to water vapour and “breathes” to prevent the build-up of moisture and subsequent movement of salt laden moisture from travelling in to the lower parts of the adjacent walls.

To dry out walls and control rising damp, Unilit 30 stabilising plaster is effective particularly where the walls are solid and the injection of a damp-proof course is either not feasible or permitted in listed buildings. Lime floors offer major benefits in traditionally built construction in comparison to membranes and cement/concrete floors.

Thermal Improvement & Time Saving Advantages

A lime slab is not required when using compacted TECHNOpor® glass foam granulates to create an insulated sub-base that can be topped with either a pre-blended Unilit screed or a site mix of Fen-XA NHL5 and a 0-5mm well graded sharp washed sand from 65-100mm thickness. This can be an economic method and can result in time savings.

Lime Screed with Underfloor Heating

The screed is laid in two layers, the first to the thickness of the heating pipes – approximately 25-30mm. A stainless steel wire mesh reinforcement (approximately 5cm spacing) is recommended to absorb the thermal stresses in the flooring due to the heating system. This is laid in the second layer of screed applied over the mesh to a minimum 40mm thickness. Greater thickness can be applied up to 100mm in the two layers.

TECHNOpor® Technology

TECHNOpor® is glass foam granulate (glass foam gravel) offering an ecological alternative for insulation to floors.

TECHNOpor® Perimeter 50 is a lightweight, breathable aggregate made from recycled glass, is capable of being used as a load bearing hardcore and has better Lambda value than alternatives. It therefore needs less depth for the same thermal performance.

TECHNOpor® has a Lambda thermal performance of around 0.08, is very stable and load bearing with an impressive compressive strength of approximately 500kN/m².

The properties of TECHNOpor® are as follows:

Structural Ability

  • The lattice structure creates a high compressive strength @ 500 kN/m²


  • The uniformed grain size & fines create the highest degree of drainage capacity without causing settlement in the building or slab


  • Meets the highest standard for inert building material
  • Leaching tests did not show any adverse effects

Fire Resistance

  • In compliance with Euro Class A1 sintering point above 700°C
  • Due to the inert properties of glass boasted by the air filled pores, TECHNOpor® provides excellent fire protection by preventing thermal conductivity


  • Neither humans nor the environment are affected by the processing or the finished product

Click the PDF image to view the technical information in full

Insulated Lime Floors

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Telling Lime Ltd
Booths Hall
Booths Park
Chelford Road
WA16 8GS

Email Telling Lime

Tel: 01565 756110
Fax: 01565 872999

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