Wales: where building regulations diverge from England

Building regulations in Wales are not the English regulations with a Welsh cover. Powers over building regulations for buildings in Wales transferred to Welsh Ministers at the end of 2011, and the two sets of Approved Documents have been drifting apart ever since. A practice that downloads its guidance from gov.uk and applies it to a site in Cardiff will get the energy standard wrong, miss a fire suppression requirement that has no English counterpart, and overlook a drainage consent that is not a building regulation at all.

This article is about Wales. Welsh planning applications are determined under Planning Policy Wales and the adopted Local Development Plan.

Why the two systems diverged

Before devolution of the function, one set of regulations and Approved Documents covered England and Wales. Since the transfer, each administration has amended its own, on its own timetable, in response to its own policy.

The practical consequence is that there are two parallel libraries. The Welsh Approved Documents are published on gov.wales and the English ones on gov.uk, and they carry the same letters for different content. Part L in Wales and Part L in England are not the same document.

Welsh policy also sits on a different statutory footing. The Well-being of Future Generations (Wales) Act 2015 requires public bodies to work towards long-term goals, and that framing runs through Welsh building and planning policy in a way that has no direct English equivalent.

Energy standards and their timing

Wales made its own amendments to the energy and ventilation parts, which came into force in late 2022. The published target for new dwellings in Wales is a 37 per cent reduction in carbon emissions against the previous standard, compared with the 31 per cent uplift England introduced in 2021. Check the current Welsh Approved Document before you fix a specification, because both administrations have signalled further change.

What the gap means in design terms: a dwelling designed to comply in England may not comply in Wales on the same fabric and services. The usual adjustments are to fabric efficiency, airtightness, and the heating system, with heat pumps doing more of the work in the Welsh calculation.

Two practical points for a cross-border practice.

The compliance calculation has to be run with the Welsh version of the methodology and the Welsh target, by an assessor who works in Wales regularly. And where planning policy or a condition requires a percentage improvement on the regulations, the baseline is the Welsh baseline, which changes the number that condition produces. An Energy Statement for a Welsh scheme therefore needs to be built on the Welsh standard from the start rather than converted afterwards.

Sprinklers in all new homes

This is the Welsh requirement English practices most often miss, and it has cost real money on real projects.

Wales requires automatic fire suppression systems in new residential premises. The requirement came from the Domestic Fire Safety (Wales) Measure 2011 and applies to new and converted residential premises, with new houses brought in from 1 January 2016. England has nothing comparable for houses, and its requirement for blocks of flats is based on building height.

The design consequences arrive early:

• A water supply capable of delivering the system's flow and pressure, which may need a larger connection or a tank and pump.
• Space for that tank and pump, usually at ground floor or in a garage.
• Pipe routes and drops coordinated with the structure and the services zones.
• A commissioning and maintenance regime for the occupier.

Specify the system against the relevant residential standard and get the water undertaker's confirmation of available flow and pressure in writing at design stage. A scheme that discovers the supply is inadequate after the slab is down has an expensive problem.

Where the building is larger or more complex, the fire strategy becomes a document rather than a specification, and a Fire Safety Strategy prepared by a fire engineer is the right route. That remains a fire engineering document requiring a competent professional whichever side of the border it sits.

Drainage approval is a separate consent

Schedule 3 to the Flood and Water Management Act 2010 was brought into force in Wales in January 2019. It is not in force in England.

The effect is that construction work in Wales with drainage implications, above a small threshold, needs its drainage system approved by a Sustainable Drainage Systems Approving Body before work starts. The approving body sits within the local authority and is separate from both the planning function and building control.

So a Welsh scheme can have planning permission and still be unable to start, because it has no drainage approval. Three things follow:

1. Programme the application in parallel with planning, not after it.
2. Design to the Welsh statutory standards for sustainable drainage, which are published by Welsh Government and are not the English non-statutory standards.
3. Expect adoption and maintenance arrangements to be part of the approval rather than a condition to be settled later.

The Drainage Strategy for a Welsh site should be written to serve both the planning application and the drainage approval, which saves one round of redesign.

Water, overheating and charging

Three areas where the two systems have taken different routes and where assumptions are dangerous.

Water efficiency is dealt with in Part G in both systems, but Wales applies its own consumption requirement, so take the figure from the Welsh Approved Document rather than the English one.

Overheating was given a dedicated Approved Document in England. Wales has approached the same risk differently, and the Welsh position should be checked rather than assumed, particularly on single aspect flats and south facing glazing where the English assessment method is not necessarily the one that applies.

Electric vehicle charging also has a dedicated English Approved Document. For a Welsh scheme, check whether an equivalent requirement is in force and what Planning Policy Wales and the Local Development Plan ask for, because the provision may come through planning rather than through the regulations.

Transitional provisions to watch

Each amendment comes with transitional arrangements, and they are the mechanism by which a project stays on the older standard. The usual structure is that work must have been notified before a stated date and must have started, building by building, before a later one.

Two things to get right. The transitional test is normally applied to each individual building rather than to the site as a whole, so a plot that has not started by the deadline falls under the new standard even if its neighbours did not. And the notification has to be the right kind, which means confirming with the building control body that what you lodged qualifies.

Record the transitional position for every plot in a schedule and keep the dated evidence. On a phased scheme this is the single most valuable piece of record keeping available.

The higher-risk building regime created by the Building Safety Act 2022 is also being implemented differently in Wales, so do not assume the English gateway process applies to a Welsh tall building. Confirm the route with the Welsh building control authority before programming the design stages.

Keeping a cross-border practice straight

Four habits that prevent most of these problems.

Keep two separate Approved Document sets in the office, clearly labelled by nation, and never cite one in a document for the other jurisdiction. Put the nation at the top of every specification and compliance note. Use consultants who work regularly in Wales for the energy calculation, the sprinkler design and the drainage approval. And treat the drainage approval as a consent with its own programme, not as a condition.

The same discipline applies to the documents you submit with a planning application. PlanScope's drafting is grounded in English policy, so a Welsh submission needs its national policy references checked and replaced by whoever reviews the draft.

Before you start a Welsh project, download the Welsh Approved Documents, confirm the water supply for the suppression system and open the drainage approval conversation with the local authority. You can browse the report types by category to see which supporting documents the application will need.

This is general guidance, not legal advice. Check the position with your building control body, the drainage approving body or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.