HOTTING UP
David Wilson, UK Technical Services Manager at Building Adhesives Ltd (BAL),
explains the importance of selecting the right products when tiling over underfloor heating.
For any tiling project, particularly those with underfloor heating, it is crucial to ensure that the subfloor is adequately prepared and that the right products are selected for fixing.
This is because heated floors create pronounced fluctuations in temperature, creating movement stresses in the installation during the heating and cooling cycles.
It is important, therefore, that the coefficient of thermal expansion of the rigid tiled finish does not vary too much from the heated subfloor. This is because small changes in expansion and contraction exert greater stresses on rigid tile finishes. In addition, in order to reduce the risks of tiles cracking or de-bonding, adequate preparation and, where applicable, commissioning of the floor heating system is crucial; as is the correct selection of adhesive and grout.
When installing tiles or flooring over a hot water pipe system, it is essential that the screed is fully dried. In the case of reinforced cement:sand-based screeds, this can range from six days, with a product such as BAL Quickset Cement, to a minimum of three weeks for a screed containing Ordinary Portland Cement (OPC), before commission of the underfloor heating.
For calcium sulphate screeds, whether anhydrite or alpha hemihydrate screeds, surface preparation and drying time is particularly important. The drying time is dependent upon the thickness of the screed and could be extended further, dependent upon site conditions. As a general rule of thumb, the drying time for a calcium sulphate screed, so the moisture content reaches 0.5% water by weight (generally accepted best practice), is approximately 1mm per day, up to 40mm in ideal drying conditions – i.e. air temperature of 20C with a relative humidity not greater than 65%.
twitter.com/TContractFloors UNDERFLOOR HEATING | 49
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70