We work in conjunction with specialist screeding contractors to offer combined Underfloor Heating and Screed packages. All screeds are specified and laid to British Standards.
When planning for an underfloor heating and screed installation the customer must ensure their floor area is suitable. The base slab must be clean and level (i.e. to British Standard with a +/- deviation of 5 mm) and with finished floor levels indicated.
The depth from the base slab to finished floor level must be enough to accommodate the insulation and screed. (The underfloor heating pipes are buried in the screed and therefore don't add to the height requirement).
If floor levels are out the screed thickness may increase leading to additional costs, or worse if the screed thickness is reduced, cover over the heating pipes may be insufficient.
Screeds come in a multitude of thicknesses and compositions, the main ones are listed below.
Fibre ScreedThis is the most common screed installed over underfloor heating, typically being laid 75 mm thick. It is a factory mixed sand and cement levelling screed with polypropylene fibres which reduce the likelihood of cracking.
Anhydrite ScreedThis is a flowing floor screed using an alpha hemihydrate calcium sulphate. An advantage is that the screed is immediately ready to use following delivery. The product is produced by Tarmac & Lafarge Gyvlon. Anhydrite screeds are perfect for incorporating thermal and acoustic insulation and underfloor heating. For underfloor heating the insulation must be tanked to prevent the screed leaking under the insulation. Not suitable for wet areas or where falls to drains are required.