Installing underfloor heating (UFH) in a refurbishment property can present major challenges and it is vital to ensure that the system is suitable. Insulation in the existing property needs to be brought broadly in line with the requirements of Part L of the Building Regulations;
Of the three standard floor constructions available - floating floor, suspended timber and screed – suspended timber floors have little impact on floor height build-up, although ceilings or floors will have to be removed in order to lay the floor heating tube. This is acceptable if they are being replaced anyway but if they have to remain in-situ a floating floor is a better solution. The floating floor construction is a popular option for retrofitting UFH due to minimal floor height build-up and straightforward installation, as it is laid over the existing deck. An average floor height build-up of 150mm means that screed is better suited to renovation projects where floors are being removed or sufficient height is available.
Sometimes a refurbishment property doesn’t appear to tick the boxes for UFH, but that doesn’t necessarily rule it out, and is where the use of a supply and design company can really help. This bungalow had 60mm loft insulation, 30mm floor insulation and no wall insulation, but heat loss calculations indicated that by using Nu-Heat’s floor construction SL14 (14mm Fastflo® in liquid screed with cliptrack), the system would achieve the required comfort levels. The owners agree that it has been exceptionally successful, especially as the primary heat source is an air source heat pump.
Victorian villa – single zone
UFH was retrofitted into the hallway of an 1850s Victorian property with a joisted floor, and issues concerning very high ceilings (3.2m) and thresholds into other rooms. Heat loss calculations showed that the presence of an enclosed porch at either end of the hallway made UFH viable, and hardwood thresholds were made to disguise the difference in levels between the hall and other rooms. The UFH was put between the joists with insulation and foil below. The floor covering used was ceramic tile with flexible adhesive and grout. The owner is now having UFH put into the new kitchen extension as they were so pleased with the system in the hall.
In many refurbishment projects, the installation of UFH is likely to be feasible, and once a good design and supply company has the project details they should give frank and unbiased advice on the viability of such a system.