Underfloor heating in Wales: Part L Wales, new builds and renovations

Building regulations are devolved in Wales, so the Approved Documents that apply in Cardiff, Wrexham or Aberystwyth are published by the Welsh Government, not Westminster. The documents share their lettering with England, Part L still means conservation of fuel and power, but the figures, dates and extras differ, and the Welsh versions are the ones your building control body works to.

For underfloor heating the differences mostly push in its favour: Wales wants lower-carbon homes, lower flow temperatures and heating that is ready for heat pumps, and a heated floor is the emitter that delivers all three. This guide covers the Welsh Part L 2022, the 55°C rule, what is coming next, grants and VAT, and how delivery works. For the English rules, see our guide to underfloor heating, Part L and the Future Homes Standard.

Does Wales have its own Part L?

Yes. The Welsh Part L 2022 came into force on 23 November 2022, five months after England's June 2022 uplift, and it goes further. Do not quote England's figures on a Welsh job; the headline differences are:

The Welsh Government has also set the direction of travel: new homes from 2025 are intended to produce at least 75% less CO2 than those built to the previous requirements, as a step towards near-zero emissions from new buildings. In practice that means new Welsh homes are being designed around heat pumps and low-temperature heating now, rather than retrofitted later; the 2021 ministerial statement behind the 2022 uplift said all new homes must be future-proofed so low-carbon heating can be fitted more easily.

What does the 55°C flow temperature rule mean for underfloor heating?

It means the heating system must be designed for cool water. Under the 2022 changes, where a wet central heating system is newly installed, in a new build or as a full replacement in an existing home, all parts of the system should be sized to enable a maximum flow temperature of 55°C or lower.

For radiators that is demanding: at 55°C a radiator gives out far less heat than at a traditional 70 to 80°C flow, so compliant radiators get large. For underfloor heating it is business as usual. The floor is a huge emitter, so wet underfloor heating is normally designed around flow temperatures of roughly 35 to 50°C, comfortably inside the rule, and a heat pump later drops that further. Our guide to UFH flow temperatures with boilers and heat pumps explains the numbers.

The practical upshot for a Welsh renovation: if you are replacing a whole heating system anyway, underfloor heating is one of the simplest routes to a system that meets the 55°C requirement without oversized radiators on every wall, and it leaves the house ready for a heat pump. See underfloor heating with a heat pump for the pairing.

Do I need building regulations approval for underfloor heating in Wales?

It depends on the job, exactly as elsewhere in the UK, but always against the Welsh documents.

• New builds and extensions: the heating and the floor insulation form part of the building regulations submission, assessed against the Welsh Part L 2022.
• Replacing a whole heating system: controlled work, and the 55°C sizing guidance applies to the new system.
• Boiler and gas work: a Gas Safe registered engineer, who can self-certify.
• Electric underfloor heating: the final connection must be made by a qualified electrician under Part P and BS 7671, which apply in Wales as in England.

If your architect, SAP assessor or building control body asks for the heating specification, give them the design flow temperature, the pipe layout and the controls, and make sure any paperwork cites the Welsh editions of the Approved Documents.

What grants can you get in Wales?

Wales is covered by the Boiler Upgrade Scheme, which is open to people in England and Wales. It gives £7500 towards an air source or ground source heat pump when you replace a fossil fuel system (gas, oil, LPG or electric), through an MCS certified installer, and until March 2027 there is an extra £1500 for properties heated by oil or LPG with no mains gas connection. Most new builds are not eligible, and hybrid boiler-plus-heat-pump systems are excluded.

Lower-income households can also look at the Welsh Government Warm Homes Nest scheme, which offers free energy efficiency advice to everyone in Wales and packages of free home energy efficiency improvements for eligible low-income households.

On VAT, the usual UK rule applies. Until 31 March 2027 the 0% VAT rate on energy-saving materials applies only where a qualifying installer supplies and installs qualifying measures; from 1 April 2027 it is due to revert to the reduced 5% rate. Buying kit supply-only from a merchant, including MaxHeatUFH, is standard-rated, so our prices include 20% VAT. Our guide to underfloor heating grants and VAT covers the detail.

Which underfloor heating suits Welsh homes?

Everything in the UK toolkit works in Wales; the choice follows the floor, not the postcode.

• New builds: PERT-EVOH oxygen barrier pipe clipped over floor insulation and screeded, designed for a heat pump from day one.
• Older solid-floor cottages and terraces: low-profile overlay boards add underfloor heating over an existing slab without deep excavation, which matters in older Welsh stone housing stock where digging out floors is disruptive.
• Suspended timber floors: spreader plates between the joists heat the floor from below without raising it.

In a draughty older property, insulate and draughtproof as part of the job; the 55°C rule is far easier to meet when the heat loss is low. Browse complete systems in the water underfloor heating range.

Does MaxHeatUFH deliver to Wales?

Yes. Orders placed by 12pm Monday to Friday are delivered next working day across the UK, including Wales. There are 30-day returns and trade accounts with trade prices for installers. MaxHeatUFH supplies but does not install; we work with vetted approved installers across the UK, so you can order supply-only for your own installer or send an installation enquiry and we will pass the project to an approved installer and support them on the install.

Frequently asked questions

Is Part L different in Wales?

Yes. Wales publishes its own Approved Documents, and the Welsh Part L 2022, in force from 23 November 2022, requires a 37% carbon cut for new homes against the 2014 standards, a minimum EPC of B for new builds, and smart controls with remote access, going beyond England's 2021 uplift.

Does the 55°C flow temperature rule apply to underfloor heating?

It applies to the heating system as a whole when it is newly installed or fully replaced, and underfloor heating passes easily: wet UFH is normally designed for flow temperatures of roughly 35 to 50°C, below the 55°C maximum the guidance asks systems to be sized for.

Can I get the Boiler Upgrade Scheme in Wales?

Yes. The scheme is open to people in England and Wales: £7500 towards an air or ground source heat pump, plus £1500 more until March 2027 for oil or LPG heated homes with no mains gas connection. Your MCS installer applies for it.

Do new Welsh homes have to have heat pumps?

Not by name, but the 2022 standards push hard that way, and the Welsh Government's stated plan is that new homes from 2025 produce at least 75% less CO2 than under the previous requirements, with all new homes future-proofed for low-carbon heating. Underfloor heating suits whichever low-carbon source is chosen.

Do I pay VAT on underfloor heating kit in Wales?

Supply-only purchases include 20% VAT, from MaxHeatUFH or any merchant. The 0% rate applies only where a qualifying installer supplies and installs qualifying energy-saving measures, and it is due to revert to 5% from 1 April 2027.

How quickly can MaxHeatUFH deliver to Wales?

Next working day on orders placed by 12pm Monday to Friday, anywhere in the UK including Wales.

Sources: Welsh Government: written statement on energy efficiency measures for all new homes, GOV.UK: Boiler Upgrade Scheme, Energy Saving Trust: Welsh Government Nest scheme, VAT (Installation of Energy-Saving Materials) Order 2024 explanatory memorandum