Electric Underfloor Heating Wiring: What You Should Know Before You Tile

We get a familiar phone call quite often around Brentwood, Shenfield and the nearby villages:

“We are redoing the kitchen / bathroom and thinking of putting electric underfloor heating in. Is it a good idea and what do we need to do on the electrics?”

Done properly, electric underfloor heating (UFH) can be a really nice touch. Warm tiles, fewer radiators on the walls, and a very even heat in the room. Done badly, it is expensive to run, awkward to control and a pain to fix once the floor is down.

This guide runs through where electric UFH makes sense, how it compares with radiators, what UK wiring rules actually say and how we normally handle it on site.

Why people in Brentwood and Shenfield are asking for underfloor heating

In this patch of Essex there are a lot of:

• Kitchen extensions with big tiled floors
• New open plan living spaces
• Refurbished bathrooms and ensuites

Underfloor heating appeals because:

• It frees up wall space where a radiator would usually go
• It gives a more even, radiant warmth from the floor up
• It pairs nicely with modern insulation and large glazed areas

Energy Saving Trust explain that there are two main types of underfloor heating:

• Wet systems with warm water in pipes
• Dry systems with electric cables or mats under the floor

For many retrofits and single room projects, electric systems are chosen because they are thinner and easier to install than a full wet system, especially where the rest of the house is staying on radiators.

Electric vs wet underfloor heating: quick comparison

Energy Saving Trust and several independent guides all say roughly the same thing:

• Electric (dry) underfloor heating
  • Cheaper and simpler to install
  • Good for single rooms and refurb projects
  • More expensive to run per kWh than wet systems
• Wet underfloor heating
  • More expensive to install, often needs floor build up or major works
  • Works very well with condensing boilers and heat pumps
  • Can be cheaper to run, particularly with low temperature heat sources

One major supplier notes that electric UFH (Under Floor Heating) can be three to four times more expensive to run than radiators or a wet UFH system, depending on tariffs and usage patterns.

So in practice we rarely suggest electric UFH as the main heat source for a whole older house. Where it shines is:

• Bathrooms and ensuites
• Kitchens and open plan ground floors in well insulated spaces
• Specific rooms where comfort underfoot matters more than total running cost

For whole house heating, low temperature wet UFH with a condensing boiler or heat pump often comes out ahead on running cost, especially as the UK moves towards more efficient heating under the government’s heat and buildings strategy.

Where electric underfloor heating works really well

From what we see day to day around Brentwood and Shenfield, there are a few “sweet spot” rooms.

Bathrooms and ensuites

Warm tiles first thing in the morning are hard to beat. In many homes the towel rail keeps the room warm enough, and UFH acts more as a comfort layer.

Because bathrooms are classed as a special location in BS 7671, you have to follow strict rules on zones and RCD protection. The IET bathroom wiring guidance and several bathroom zone guides emphasise:

• All bathroom circuits must be RCD protected
• Cables and heating elements in zones 1 and 2 must meet specific IP ratings and be on 30 mA RCDs
• All fixed bathroom electrics must comply with BS 7671 and the zone layouts

That is one reason we always tie bathroom UFH into the overall bathroom wiring plan, rather than treat it as a separate “kit”.

Kitchens and open plan living areas

If you are retiling the whole ground floor, putting UFH under the new screed can give a lovely even heat and free up walls from radiators.

Independent comparisons suggest that underfloor heating can run at lower water or surface temperatures and can be up to 25 percent cheaper to run than traditional radiators when used with modern boilers and even more with heat pumps.

With electric UFH the key is:

• Good insulation under the heating mats
• Sensible zoning and controls
• Not using it as the only heat source in a poorly insulated room

Garden rooms and studios

Where you have a well insulated garden room and no wet heating, an electric underfloor system can be a neat way to avoid cluttering the space with wall heaters.

We often pair this with simple electric panel heaters or smart heating controls so you are not paying to heat the garden room at full power all day.

Wiring and safety: what the regulations actually say

Most of the customers we visit do not want each chapter and verse of the Wiring Regulations, but they do want to know that the electrics are done properly.

Here are the important bits.

Protective earthing and RCDs

IET Wiring Matters and IET guidance on floor and ceiling heating systems explain that:

• Electric floor heating elements must be installed with either a metal sheath, metal enclosure or a fine metallic grid connected to the protective conductor
• The heating system must be protected by an RCD with a rated residual operating current not exceeding 30 mA
• Special care is needed to avoid damage to cables and to provide additional protection where there is a higher risk of fire or shock

Bathroom zone guides add that any UFH cables running through zones 1 and 2 must be RCD protected and installed according to BS 7671 Section 753 and the manufacturer’s instructions.

Dedicated circuits and load

Because UFH can draw a fair bit of current, we usually put it on dedicated circuits from the consumer unit rather than tack it onto an already busy ring.

Typical approach:

• New radial circuit sized for the total UFH load in that zone
• Local isolator outside the bathroom or in an accessible position
• Thermostat and controls wired in accordance with the system design

If your consumer unit is old or has limited RCD protection, this is often the moment when a consumer unit upgrade or at least an EICR is worth talking about, which we covered in detail in our earlier articles on:

• EICR testing for landlords
• Consumer unit upgrades and modern RCD protection

(Your web team can link this post to those blogs once they are live.)

Who can install what: DIY vs electrician

A lot of electric UFH kits are sold in DIY sheds and online. The small print usually says something like:

“Matting can be laid by a competent DIYer, but all electrical connections must be made and tested by a qualified electrician.”

One installer guide spells it out clearly: laying the mat or cable is one thing, but continuity and insulation resistance testing, thermostat wiring and connection to the mains must be done by a competent electrical contractor who can test and sign off the work for Building Regulations.

Our typical division of labour on projects in Brentwood and Shenfield:

• Tiler or main contractor:
  • Prepares the subfloor
  • Lays insulation boards if needed
  • Lays the UFH mats or cables following the design plan
• Volt East:
  • Checks the heating element resistance before and after laying
  • Runs the supply cable back to the consumer unit or local point
  • Installs the thermostat and any floor probes
  • Connects, tests and certifies the circuit to BS 7671

That way everyone stays in their lane and the homeowner gets a properly documented system.

Rough costs and running cost expectations

Money always comes up in the conversation, so it is worth giving some ballpark figures.

Independent cost guides and Energy Saving Trust data say:

• Electric UFH supply and install often comes in around £50 to £85 per square metre for typical domestic jobs
• Wet systems can be in the £85 to £110 per square metre range
• Electric systems are usually more expensive to run than wet systems on gas or heat pumps, unless you are very disciplined with timers and zoning

The key takeaway we share with customers:

• Electric UFH is best treated as a comfort upgrade or a targeted heating solution in key rooms
• Do not plan to run it flat out all day in a poorly insulated space
• Combine it with decent insulation, good controls and sensible set points

If you are more focused on whole house efficiency, our recent post on energy saving electrical upgrades and our article on smart heating controls are worth a read too, and your team can cross link those from this page.

How Volt East usually handles UFH jobs around Brentwood

On the electrical side, a typical project with us looks like this:

1. Design chat
   We talk with you and your builder or tiler about which rooms are getting UFH, what type of floor build up you are having and what the main heating system is.
2. Check the board and wiring
   We look at your consumer unit and existing circuits to see if we need new ways back to the board or if there is spare capacity. If things are very dated, we might recommend an EICR or a board upgrade first.
3. UFH circuit design
   We plan the size of circuits, RCD protection and thermostat locations so everything stays compliant and tidy.
4. First fix and testing
   We run cables, connect thermostats and test the heating elements at the correct stages before the floor goes down.
5. Final connection and sign off
   Once tiling or floor finishes are done, we power up, test, and show you how to use the controls.

On many jobs we combine this with:

• New LED lighting and switching in the same rooms
• Integration with home automation for app control and scenes

FAQs: Electric underfloor heating in and around Brentwood

Is electric UFH too expensive to run with current electricity prices?

It depends what you use it for. Suppliers and cost guides point out that electric UFH can cost three to four times more per kWh than a wet system on gas, but if you only use it in a bathroom or kitchen for timed comfort, the absolute cost can still be reasonable.

Can I just connect the mat into a local spur myself?

You really should not. Underfloor heating is a fixed electrical installation, not a plug in appliance. IET and manufacturer guidance is very clear that the final connection, testing and certification must be done by a qualified electrician working to BS 7671 and building regulations.

Do I need an RCD for underfloor heating?

Yes. Current Wiring Regulations and bathroom zone guides require RCD protection for UFH circuits, especially when they run in bathroom zones. In practice we will always put electric UFH on 30 mA RCD protected circuits.

Is it better than radiators?

Comfort wise, many people prefer the feel of warm floors and even heat. Cost wise, it depends on the type of system and what powers it. When paired with a condensing boiler or heat pump, wet underfloor heating can be up to 25 to 40 percent cheaper to run than standard radiators according to industry data. Electric UFH, by contrast, is more of a targeted comfort solution than a cheapest possible heat source.

If you are planning new tiles or a full refurb in Brentwood, Shenfield, Hutton or the surrounding villages and are on the fence about electric underfloor heating, we are happy to walk it through with you.

We can look at your existing electrics, explain the wiring and safety side in plain language and give you a straight answer on whether UFH is the right call or if a different heating setup would suit your home better.