Trades master copy
Last reviewed: March 2026
What Part S is
Part S is the EV charging bit of Building Regulations. It says when you have to provide electric vehicle charge points or at least cabling so they can be added easily later.
The aim is simple: if you're building new homes or doing big refurbs with parking, you build in charging from day one rather than digging it all up again in five years.
This guide is a summary to make Part S easier to use on site. It does NOT replace Approved Document S: Infrastructure for charging electric vehicles (current edition).
You must read and follow the full Approved Document S and the DNO/charger manufacturer guidance on load, cabling and protection.
This guide is written for England. Wales, Scotland and Northern Ireland have their own versions of building regulations - the principles are similar but the documents and approval routes differ, so check local requirements if you're working outside England.
Where it applies on your jobs
For small builders, Part S mainly bites when:
- You're building new houses or flats with associated parking (driveways, on-plot bays, garages, or spaces in a car park that belong to that dwelling).
- You're converting existing buildings into dwellings (barns, offices, shops to resi) and those new dwellings have parking.
- You're doing a major renovation of an existing residential building with more than 10 parking spaces when you're done.
Key point: Part S is only about associated parking on the site. On-street parking and car parks outside the site boundary don't count.
Key "trigger points" - when you actually need EV stuff
New residential buildings - houses and flats (S1)
If you build a new dwelling and it has associated parking, you must give that dwelling access to a charge point.
The rule for new residential buildings is essentially:
- Minimum of one charge point per dwelling with parking, or
- One charge point per parking space, where that's fewer.
Examples:
- 1 house, 2 spaces on the drive → at least 1 point.
- Block of 10 flats with 8 spaces in the residents' car park → every space needs a point (8 spaces).
- Block of 10 flats with 20 spaces → at least 10 spaces need points (1 per dwelling).
Dwellings from material change of use - barns, offices to resi (S2)
- If you're converting a building to create one or more dwellings and they have associated parking, each dwelling must have at least one associated parking space with access to a charge point.
- Heritage/listed/traditional buildings can sometimes get dispensation - that's one to clear with Building Control early.
Residential buildings undergoing major renovation (S3)
If you're doing a major renovation to a residential building and there will be more than 10 parking spaces when you're finished:
- At least one associated parking space per dwelling must have access to a charge point.
- All the additional associated parking spaces created by the works must have cable routes installed ready for future chargers.
- There's a cost cap: if doing full chargers and cabling would cost more than a set percentage (7% of the renovation cost), you can drop back to cable routes only - check AD S for the detail.
Small-print worth knowing
- Part S also covers non-residential and mixed-use with more than 10 spaces (S4), but most small domestic builders won't touch that often.
- Car parks outside the red line or on-street bays aren't "associated parking", so Part S doesn't force you to wire the road.
Routes to compliance for trades
For you on site, this boils down to: count the spaces properly, put points/cabling where the regs say, and size your electrics sensibly.
Count associated parking and agree the EV strategy early
At design stage, confirm:
- How many dwellings.
- How many on-plot/allocated spaces per dwelling.
- Whether it's new build, change of use, or major renovation with >10 spaces.
From that, the designer should tell you:
- How many actual charge points.
- Which spaces just get cable routes for future points.
Electrics and charger spec
Typical expectation is 7 kW AC chargers on domestic jobs (either tethered or untethered depending on the spec), sized and protected in line with BS 7671.
You need:
- Adequate supply capacity (check with the DNO where needed).
- Correct cable sizes and routes.
- RCD/RCBO protection and, if needed, PEN fault protection or equivalent device as per current EV charger standards.
Don't promise "chargers everywhere" in a block before someone's checked the main incomer and diversity assumptions.
Cable routes
Where the regs say "cable routes", you don't fit the charger now; you:
- Run suitable conduit/ducting and draw wires or pulled-in cables from the distribution board or feeder point to each space.
- Leave access so chargers can be fitted later without smashing up the finished car park.
Overlap with other Parts
Part S overlaps with:
- Part P (electrical safety).
- Part B (fire safety - especially in covered car parks).
- Part M (accessible spaces) - at least one accessible bay will normally need EV provision in bigger schemes.
Don't treat the charger as "just another socket"; cable routes and locations can affect fire and accessibility layouts.
Who is responsible for what
On a typical domestic or small scheme:
- The designer is responsible for working out the Part S obligations (how many chargers, how many cable routes, which spaces) and coordinating with the DNO on capacity where needed.
- The builder/main contractor is responsible for making sure the right ducts, cables and isolation points are built in - not "forgetting" them because the client hasn't bought an EV yet.
- The electrician/EV installer is responsible for designing and installing the actual charger circuits to BS 7671, manufacturer instructions and Part P, and for labelling/isolation.
- The client/owner/developer carries the hit if they duck Part S - Building Control can hold up completion, and future buyers will ask where the charging is.
Blunt version:
If you pour the drives, stripe the bays, and only then realise nobody ran the EV ducts, you're breaking it up on your own time. Same if you decide "we'll leave chargers out to save a bit now" - Part S doesn't care whether the current buyer owns an EV.
Simple rule to drum into your team
If you're building or converting homes with parking, assume it's a Part S job. Count the spaces, check the drawings for points/ducts, and don't concrete until the EV infrastructure is in.
On-site checklist (Part S)
Before you start
- Confirm: is this new build, change of use, or major renovation with >10 spaces?
- Count associated parking spaces per dwelling and agree the number and location of charge points and cable routes.
- Check with the electrician/DNO that the supply and main boards are sized for the EV load strategy.
While you're working
- Install ducts/cable routes from boards to each required bay or feeder pillar before you finish hard landscaping.
- Mark and protect cable routes so they aren't cut or buried under unexpected walls or kerbs.
- Coordinate with fire/access layouts in covered or shared car parks.
When you finish
- Make sure the specified number of chargers are installed, live and tested where required, and that the remaining "cable-route only" spaces really have usable routes.
- Label EV circuits and isolation clearly at the consumer unit/feeder.
- Hand over charger manuals, certificates and as-built EV layout to the client and Building Control.
Sources
Based on:
- Approved Document S: Infrastructure for charging electric vehicles (2021, in force from June 2022).
- Government FAQs and industry guidance on how many charge points/cable routes are needed on different dwelling/parking setups.
- Practical developer/installers' guides on Part S load, charger sizing and coordination with other Parts (B, M and P).
This guide was last reviewed March 2026. SiteKiln does not provide legal, financial or tax advice. All content is for general information purposes only. Always seek professional advice for your specific situation.
Know someone who needs this?
Working in Wales? The building rules are different. See our Working in Wales guides.
Working in Scotland? Building standards work differently. See our Working in Scotland guides.
Working in Northern Ireland? The system uses Technical Booklets. See our Working in Northern Ireland guides.
Was this guide useful?
Didn't find what you were looking for?
Spotted something wrong or out of date? Email us at hello@kilnguides.co.uk.
In crisis? Samaritans 116 123 ·