Underfloor heating: your essential guide to retrofitting

Underfloor heating is one of life’s luxuries many of us dream of and when you move to a new home, you may be presented with an opportunity to install warmth underfoot. Yes, there will be some work involved when moving away from radiators but installing underfloor heating isn’t an impossibility. In this article, we explore what’s involved when retrofitting.

What is retrofitting 

Retrofitting is the process of adding something that wasn’t there at the start. If you’re looking to move, you will almost always have to retrofit underfloor heating, unless you’re buying a brand new home where it’s part of the specification. Most commonly, homes are heated using a boiler-powered central heating system and, more recently, air source heat pumps, with wall-mounted radiators providing the heat.

Your most pressing question will probably be ‘do I need to rip floors up to install underfloor heating?’. As the system works by laying pipes or cables beneath a floor covering, a level of disturbance is to be expected but let’s look at the options.

Integrated underfloor heating

If you’re moving to an older home with the intention of renovating, changing the floor structure is a great time to add an integrated underfloor heating system. If the existing subfloor is concrete, it’ll probably need digging up to install an integrated system. An alternative is to explore ‘milling’, when channels are cut into concrete and underfloor heating pipes inserted into the gaps. A drawback to milling is a lack of insulation under the pipes, which impacts energy efficiency.  

If the existing subfloor is joisted, pipes can be laid in between the joists and insulation added, which is less disruptive. There is a fourth retrofitting option if the property is very new. Modern building standards mean the top layers of a subfloor can be screed and insulation, which is easier to dig up. Underfloor heating can then be installed and new screeding added after completion. 

Overlay underfloor heating

The most cutting edge underfloor heating can be installed without excavation work. Generally, the top floorcovering will need to be removed – such as carpet or laminate – to expose the subfloor, which is usually floorboards, tiles or concrete.

You may need to insulate under joisted floors, smooth out bumps and level the floor in preparation but generally no digging is required. Slimline/low profile underfloor heating is laid on top, and is usually thin enough to avoid increasing the height of doorways and ceilings. A self-levelling compound is commonly poured over to create a new, solid floor.

Types of underfloor heating available

‘Wet’ underfloor heating: works by hot water being pumped through pipes. Wet underfloor heating can be powered by a boiler-run central heating system or by an air source heat pump. A wet system is usually the most expensive option to install but it normally costs less to run in the long term.

‘Dry’ underfloor heating: no water is involved in dry underfloor heating. Instead, cables or pre-threaded mats are laid, through which electricity flows. A dry system can be cheaper to install than wet underfloor heating but the running costs are usually high.

Underfloor heating considerations

• Although rare, wet underfloor heating can spring leaks - remedial work could involve taking up the floor and possibly the subfloor

• Check that the timber floor you have is compatible with integrated underfloor heating

• Both wet and dry underfloor heating can be damaged from above, especially when items are fixed to the floor

• Underfloor heating repairs can be more complex than fixing a radiator, for example

• Not every underfloor heating system works with carpet, so check compatibility

• Air source heat pumps and underfloor heating can offer a very energy efficient heating combination

• The best outcome when retrofitting underfloor heating is when a professional trade is used

• Electric generally costs more than gas, so factor in running costs

If you’ve got a renovation itch you need to scratch, want to move to a new area or need more space, contact us for the latest available properties.