Working in Wales: Building Regulations Differences You Need to Know

‍‌‌‌‌​‌‌‌‌‌‌‌‌‌‌‌​​‌‌​​‌​‌‌​​‌‌‌​‍# Working in Wales - building regulations differences you need to know

If you treat Wales as "England with a different flag," you're going to get caught out. The legal framework looks similar on paper, but the rules that actually bite on site are not the same.

Wales uses the Building Regulations 2010 framework like England, but with Welsh-specific Approved Documents, its own energy targets, and a different building control setup. If you work near the border, you have to mentally flick a switch when you cross it.

1. No Approved Inspectors in Wales

In England, you can choose between Local Authority Building Control (LABC) or a private Approved Inspector / Registered Building Control Approver.

In Wales, that choice has gone.

Since late 2023, there are no private Approved Inspectors in Wales. All building control runs through the local authority building control team.

If someone offers to "do your building control privately" on a Welsh job, that should ring alarm bells.

What this means for you:

• On the English side of the border: you can still shop around between council and private.
• On the Welsh side: you budget time and fees for dealing with the council only.
• You cannot carry on with your usual Approved Inspector from England and assume it's fine. It isn't.
• If you try to use an English private inspector for a Welsh job, building control in Wales can refuse to recognise the work - and you'll be the one sorting the mess out.

2. Part L (energy) - Welsh version, Welsh timetable

Both England and Wales talk about "Part L - Conservation of fuel and power." That makes it sound the same. It isn't.

Wales has:

• Its own version of Approved Document L, published by Welsh Government.
• Its own timetable for tightening standards.
• Its own numbers for things like U-values, air-tightness targets and boiler efficiencies.

England is marching towards its Future Homes Standard on its own schedule. Wales has set out its own path.

On a practical level:

• You cannot price a job in Wales off your favourite English Part L summary sheet.
• SAP / energy calculations for Wales must follow the Welsh Part L rules, not the English ones.

Typical problem areas:

• Wall / roof / floor U-values
• Glazing performance
• Air-tightness test targets
• Minimum efficiencies for heating systems

If you under-spec because you've used English figures, you risk failing compliance checks and having to upgrade insulation, glazing or kit after the fact - on your own dime.

3. Part 6 / new-build energy performance

Wales has gone its own way on energy performance for new builds. You'll see references to:

• Different target emission rates
• Different fabric energy efficiency standards
• Extra requirements on air-tightness testing and low-carbon heating

The detail lives in the Welsh Approved Documents and related guidance. The headline is simple:

A new house in Wrexham is not assessed on the same numbers as a new house 15 minutes away over the border in Chester.

If your designer or SAP assessor uses the wrong jurisdiction, you can design the whole thing to the wrong target. When that unravels, it's usually on site, when someone notices the numbers don't line up with what building control in Wales is expecting.

4. SAP and other energy calculations

SAP (for dwellings) and SBEM/BRUKL (for non-domestic) exist across the UK, but the rules they're checking against are not universal.

For Welsh jobs:

• The assessor must select Wales as the location / regulations set.
• They must use the Welsh editions of any reference tables and targets.
• You, as the builder, must actually build to those specs: insulation thicknesses, boiler type, PV sizes, air-tightness levels.

If your assessor lazily runs everything as "England" because that's what they know:

• The design looks compliant on paper but fails when Welsh building control look at it.
• You end up over- or under-specifying, which hits either your cost or your compliance.

You don't need to become a SAP assessor, but you do need to ask one simple question early: "Have you definitely run this as Wales, using Welsh Part L?"

5. Welsh Approved Documents - not just a logo swap

For a lot of the Parts, England and Wales were aligned for years. Then devolution kicked in properly and Wales began issuing its own Approved Documents.

That means:

• There is an English Approved Document L, and a Welsh Approved Document L.
• The Welsh versions may have different examples, different performance standards, and different dates from which changes apply.

When you download guidance or grab a PDF:

• Check the front cover for "Welsh Government" or a clear "Wales" marking.
• Don't trust a random Google result or an old PDF saved on your desktop.
• Get into the habit of asking, "Is this the England version or the Wales version?"

If building control in Wales asks "which document did you work from?" and you wave an English Part L at them, you're on the back foot from that moment.

6. Why this bites border builders

If you work around:

• Chester / Wrexham
• Bristol / Cardiff / Newport
• Shrewsbury / Welshpool
• Hereford / Abergavenny / Monmouth

...it is absolutely normal to have jobs either side of the border in the same month.

Here's where people fall over:

• They use the same spec sheets and standard drawings in England and Wales.
• They price off English Part L assumptions then discover the Welsh job needs thicker insulation or better windows.
• They tell the client, "We'll get our usual private inspector on it," not realising that's not an option in Wales.

That turns into:

• Extra material and labour to fix under-spec'd work
• Delays while drawings and SAP calcs are re-done
• Awkward conversations with clients who thought you had it nailed
• Hit to your reputation with local authority building control

None of this is about being stupid. It's about systems that look identical at a glance but are quietly different.

Pre-start checklist for Welsh jobs

Run through this before you price or start any job in Wales, especially if you also work in England.

1. Location and jurisdiction

• Check the site address and postcode - are you definitely in Wales?
• Note on the job file: "Jurisdiction: Wales (Welsh Building Regs)."
• Tell your designer / QS / SAP assessor outright: "This is Wales, not England."

2. Building control route

• Confirm with the client: "We'll be using the council's building control - there are no private inspectors in Wales."
• Find the correct local authority building control team for that council area.
• Get their fee quote and process (building notice vs full plans) and build that into your programme.

If someone suggests a private Approved Inspector on a Welsh job, stop and double-check before anything is signed.

3. Drawings and design assumptions

Ask the designer/architect straight:

• "Have you designed this to Welsh Building Regulations?"
• "Are your standard details for Wales, not just copied from England jobs?"

Double-check spec notes on drawings for: U-values, insulation thicknesses, window and door performance. If anything looks like it's been dragged across from an English template, get it clarified in writing.

4. Approved Documents

For any technical question, make sure you or your designer are looking at the Welsh Approved Documents, not the English ones. On every PDF, check the cover: does it clearly say Welsh Government or Wales?

Delete or clearly label any old English-only PDFs in your shared folders so nobody grabs the wrong one in a rush.

5. Energy / Part L / SAP

Tell your SAP / energy assessor up front: "This project is in Wales. Please run it under Welsh Part L."

Ask them to confirm:

• They've used the Wales settings in their software.
• The spec they give you (insulation, glazing, heating, air-tightness) matches Welsh targets.

Get their design-stage report before you finalise your price, so you're not under-allowing on insulation or systems.

6. Contract and paperwork

In your quote or contract, add a simple line:

"Works priced and carried out to Welsh Building Regulations and relevant Welsh Approved Documents."

Confirm in writing with the client that building control will be via the local authority in Wales, and any design info they supply must be compliant with Welsh regs. This protects you if someone else has quietly used the wrong standards.

7. On-site checks before key stages

Before critical points (foundations, insulation, first fix, pre-plaster):

• Check your build spec against the Welsh documents or SAP report, not an old English crib sheet.
• Confirm with the building control officer if you're unsure - make it clear you're talking about a Welsh job.
• Keep copies of the Welsh guidance you actually used in the job folder.

Pin this up: the one-pager for your van

1. Is the site in Wales? Write "Jurisdiction: Wales" on the job.
2. Building control: council only, no private inspectors.
3. Tell designer/SAP: "This is Wales, design to Welsh regs."
4. Only use Welsh Approved Documents (check the cover).
5. Price to the Welsh Part L / SAP spec, not your English standard.
6. Put "Welsh Building Regulations" in your quote/contract.
7. At each key stage, sanity-check against Welsh guidance or the Welsh SAP report.

You follow that, and you massively cut the odds of nasty surprises on Welsh jobs.

What to do next

• Read: SiteKiln Building Regulations guides (England) - understand the English baseline
• Read: Guide 15.7 - Setting up properly
• Check: Welsh Government building regulations page for current Welsh Approved Documents

Sources (UK)

• Welsh Government - Welsh-specific Approved Documents, Part L (Wales), building control policy changes.
• Building Regulations 2010 (as applied in Wales) - shared framework but Welsh-specific implementation.
• Approved Inspector removal (Wales, 2023) - no private building control in Wales.
• Welsh Part L / energy performance - different U-values, SAP requirements and Future Homes timeline.

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