Calcium Sulphate Screed
Kildea Concrete - floTherm Liquid Screed is a specially formulated calcium sulphate self leveling (flowing) floor screed. The product is a high quality factory produced screed to EN 13813.
Flowing screeds have many obvious benefits over traditional sand and cement screed: quicker to lay; thinner screed depth; less labour intensive; much lower risk of shrinkage or cracking but the main benefits are seen when they are used with underfloor heating systems. Flowing anhydrite screeds fully encapsulate the heating pipes without voids and need only to cover the pipes by 25mm, resulting in a much more responsive heating system which in turn is more economical to run.
- Apply up to 1000m² per day
- Low shrinkage
- Reduced screed thickness
- Maximizes underfloor heating
- BS EN 13813 CA - C30 - F6
Directions:
Preparation
The building must be weather tight prior to the placing of any screed material: the roof; external doors and windows must be in place and closed or covered and taped to prevent draughts.
All substrates must be suitable to receive the screed as per current good working practices.
All substrates for bonded constructions should be clean and thoroughly sound; they should be free from standing water, oils, greases, dust, loose particles or any other contaminants which may interfere with adhesion.
For floating (or unbonded) and underfloor heating constructions, it is imperative that the highest quality preparation is carried out. All insulation boards should be installed in such a way as to provide a clean even base. A suitable (500µm) polythene sheet should be applied over the insulation. All joints should be lapped to 100mm and fully taped. A suitable 5-10mm PE foam expansion strip should be fitted to the full depth of screed around the entire perimeter of the floor. Corners and joints should be constructed neatly and taped to form a watertight seal. All openings should be suitably sealed to prevent screed material escaping. Heating pipes should be laid as required and mechanically fixed every 300mm. It is recommended to also fill pipes with water to prevent lifting.
Isolation strips should be placed in door thresholds where there is likely to be a difference in operating temperature in underfloor heating circuits.
It is recommended to leave designated areas without underfloor heating pipes and clearly mark their location to allow the easy sampling for CM moisture readings without risk of damage to the heating system.
Application
The ready to use screed is transported to site by ready mix truck in quantities of 6m³ at a time.
The screed should be pumped into place using a suitable pump. The pump hoses should be first primed/lubricated with a slurry of binder and water.
The level should be set with tripod markers and a suitable laser level or water level before pumping commences.
After placing, the screed should be lightly tamped with T-bars or similar to ensure full compaction.
The screed should be protected from draughts during installation and for the first 3 days.
The screed should be dry (less than 0.5% moisture content measured by CM) before covering. This can be accelerated by the use of dehumidifiers or by commissioning of the heating system after 7 days.
Depending on the mix design, application and requirements of the floor covering it may be necessary to remove surface laitance. This can usually be accomplished by brushing with a stiff brush but may require the use of a floor buffer fitted with a suitable grinding disk. The removal of laitance is normally carried out after 7 days depending on site conditions.
Restrictions
Always isolate gypsum based materials from cement based materials when mixing. A relatively small amount of gypsum contamination in cement based mixes can cause deleterious expansive reactions.
Gypsum based screeds are not suitable for use externally or in area of permanent dampness.
Gypsum based screeds must be suitably primed prior to the application of subsequent cementitious materials, e.g. tile adhesives.
Handling Precautions
Larsen Products are generally safe provided they are used as instructed and that certain precautions normally taken when handling chemicals are observed e.g. do not allow any material to come in contact with food stuffs. Avoid contact with the skin. Do not swallow. Always read the safety information on the pack and the Safety Data Sheet before use.
Important Note
The information given in this data sheet is based on both current development work and may years of field experience. Whilst every effort is made to ensure that the information is reliable we cannot accept responsibility for any work carried out with our materials where we have no control over methods of application, site conditions, etc..