Which floor covering is best?
UFH can work in tandem with most floor finishes, but there’s no doubt some are more natural partners. The likes of stone and porcelain tiles are great conductors of heat, for instance, absorbing the warmth from the pipework and radiating it out effectively into the living space.
Laminate, vinyl and engineered wood floors offer a good heat transfer level, too, so they can all be successfully teamed with UFH – provided they’re designed to withstand with the operating temperatures (usually 27ºc). Floor sensors can be fitted at the installation stage to prevent the UFH from exceeding the maximum tolerance. You can even pair carpet with underfloor heating, provided the combined tog value is less than 2.5.
Before you make your final choice, however, you need to be sure the combination will achieve the output you need for the zone being treated. According to Nu-heat, stone and tiles can hit upwards of 70 Watts per m2 (W/m2) of heat. Vinyl sits just shy of 70 W/m2, while wood is at around 55 W/m2 and carpet with a two-tog carpet below 50 W/m2.
Pipe spacing and flow temperatures can be adjusted to deliver lower outputs as required, but this gives you a sense of what a UFH system is capable of with different coverings. Note that the rating of the UFH setup itself will higher (typically around 150-200 W/m2) than the final output achieved once the floor covering is taken into account.
and block); insulation; damp proof membrane; UFH pipes embedded in screed; and then your chosen floor finish.
Other options are available to suit specific project goals, including low-profile systems designed to minimise the height build up while still delivering good heat output. These were developed for the renovation market, since it’s difficult to add thick layers of insulation and screed to an existing house without making major changes elsewhere. Nu-heat’s Lopro range can be laid directly onto existing floors, for instance, with a total additional height build-up of just 15mm.
Self builders are now beginning to adopt these super-slim setups, too, as they recognise the benefits of gaining a few precious extra centimetres of head height on each storey (particularly if there are restrictions on the overall height of the building). Some low-profile systems are based on the use of pre-insulated ‘spreader plates’ that can sit in between joists, while others can work with thin liquid screeds.
Your UFH network will be hooked up to the boiler or renewable energy source via a manifold. This is the business end of the installation, delivering the exact mix of hot and cold water to achieve the desired temperature. Each zone you wish to heat will have its own pipe run so that it can be individually controlled by the relevant room thermostat (which might be wired-in or wireless, depending on the installation).
Installation & costs
So, you’ve set your heart on installing this hidden heating system – but how much should you budget? Well, that depends on a range of factors. Who’s designing the setup, for instance, and who’s installing it? Are you going for a standard screeded solution, or does your project require a low-profile system to minimise floor build-up?
Most self builders and renovators want the reassurance of having their UFH system specified and installed by a qualified professional. You (or your tradesperson) can get hold of multi-room UFH kits for around £20-£30 per m2, depending on the spec, total area to be treated and number of zones. Add the screed and labour to fit it, and you’ll be looking at more like £30-£40 per m2. You may be able to tighten up the budget if you have the skills and confidence to go down the self-install route – but even then, you’ll still need a pro to hook it up to the boiler and commission the UFH.
A typical bespoke system might start from around £40£60 per m2 installed (excluding the screed), although that can rise towards the £100 per m2 mark on smaller projects. But taking the design, supply and install route gives you the benefit of a single, specialist point of contact throughout the process, as well as for the lifetime of the warranty. At the higher end of this bracket, you’re looking at premium products such as thin-profile setups, systems that boost acoustic performance between storeys, and high-output options.
The exact install process will depend on the nature of the subfloor and the UFH product you’ve selected, but in general the first step will be to insulate and prep the floor structure This job would usually be done by your builder. Once this is done and the house has been made watertight, the UFH install team will position the manifolds and run the pipework (plus any infrastructure, such as cabling for controls). They’ll then pressure-test the system before hooking it up to the central heating network. You’ll want to lay your screed as soon as possible after the install to protect the pipework. Your plumber of UFH fitter will then commission the setup during the second fix stage (usually after the plastering is done).