Breathable Lime floors offer an alternative to cement concrete floors as well as providing good insulation values.
In new build construction the DPM run under the walls as well as the floor , in refurbishment of old buildings DPM should be avoided because they finish at the base of the walls at the perimeter of the floor resulting in concentrations of moisture at these points which can lead to an increase of rising dampness in the walls.
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.
4. Sub-bases consisting of TECHNOpor® PERIMETER 50 foamed recycled glass, which prevent water from rising in the walls along with providing a much better thermal performance.
Unilit Lime screeds can be made to be waterproof, but at the same time permeable to water vapour. They ensure the passage of water vapour between the floor and the interior. Where rising damp is expected to occur this can freely evaporate through the lime screed preventing the build-up of a hydrostatic pressure within the floor or building structure. The low salt content of the binder, as well as its permeability to water vapour eliminates all risk of efflorescence (salts) after the surface of the finished screed or the tiled flooring has dried.
Lime Floors – Advantages
Lime floors can provide major benefits to older traditionally built construction when used as an alternative to DPM & cement concrete floors.
By using Lime as the binder in a floor slab and screed the floor is allow permeable to water vapour “breathe” which prevents the build-up of moisture subsequent movement of salt laden water from travelling in to the lower parts of the adjacent walls.
Since the 1940’s many refurbishment of older properties up and down the country have had replacement cement floor slabs with DPMs installed This has moved moisture to the lower parts of the walls creating a further problem of the effects of rising dampness to the surface drying area of the wall plaster, the following lime flooring information will prevent the same from happening in the future.
To dry out walls and tackle the effects of rising damp please see Unilit 30 stabilising plaster.
Thermal improvement & Time Saving Advantages
The lime slab can be omitted when using compacted Technopor glass foam granulates which is an insulated sub-base this can be topped with Pre-blended Unilit C screed from 65mm – 100mm which can result in a time saving.
The lime screed can also be made by site mix Fen-XA NHL5 and 0-5mm well graded sharp washed sand.
Lime screed with under floor heating
The screed should be laid in two layers the first to the thickness of the heating pipes, approximately 25 – 30mm. To provide suitable reinforcement stainless steel wire mesh reinforcement (approx. 5cm spacing) is recommended to be laid into the screed (to absorb the thermal stresses in the flooring due to the heating system) and the second layer of screed applied over the mesh a minimum 30mm thick. Greater thickness can be applied up to 100mm total thickness for the two layers. Following layers or bedding layers should be applied 7 to 10 days after application.
TECHNOpor® is glass foam granulate (glass foam gravel) this is the ecological alternative for insulation to building 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 then alternatives so needs less depth for the same thermal performance.
Technopor® Perimeter 50 has a Lambda thermal performance of around 0.08 it is very stable and is load bearing with an exceptional compressive strength of approximately 500kn/ m². The grain sizes are 30 - 50mm granules which require to be compacted by Vibrating plate compactor where being used as flooring, 30% extra volume should be allowed for when calculating for a compacted application.
The properties of TECHNOpor® are as follows: