Most housebuilders we speak to have the first date in their heads: 24 March 2027. That’s when the Future Homes and Buildings Standards bite, and the received wisdom is “get the application in before then and you’re fine”.
It’s the second date that catches people out — and the definition sitting behind it. Getting that right now beats a nasty surprise in 2028.
The two-part test
The Future Homes Standard is delivered by The Building Regulations etc. (Amendment) (England) Regulations 2026 (SI 2026/335), made on 23 March 2026 and laid before Parliament the following day. The Regulations come into force on 24 March 2027, except that regulations 3, 4, 6, 7, 8 and 9 come into force for higher-risk building (HRB) work and work to an existing HRB on 24 September 2027.
For ordinary, non-HRB work, regulation 5 sets out the transitional protection. It applies to building work on a particular building where:
- a building notice, an initial notice, or an application for building control approval with full plans has been given to the relevant authority in respect of that building before 24 March 2027; and
- the building work to which that notice or application relates is commenced in relation to that building before 24 March 2028.
Both limbs have to be satisfied. Miss either one and the amendments made by regulations 3 and 4 — the new Part L, requirement L3 and the rest — apply to the work.
Two things are easy to miss here. The first is that this is expressed per building, not per site. An early full-plans application does not throw a blanket over a whole scheme; each individual building has to have commenced in time. The second is that “commenced” has a legal meaning, and it isn’t a generous one.
What “commenced” actually means
Regulation 5(5) is explicit: paragraphs (2) to (5) of regulation 46A of the Building Regulations 2010 apply to determine whether work is regarded as commenced. Regulation 46A was written for a different purpose — the lapse of building control approval — but it’s now doing double duty as the FHS cut-off test.
For the construction of a building (and for a horizontal extension), regulation 46A(3) says work is regarded as commenced when:
the sub-surface structure of the building or the extension including all foundations, any basement level (if any) and the structure of ground floor level is completed.
Read that again. Not “started on site”. Not “foundations poured”. The sub-structure has to be complete, including the ground floor structure, on that specific building, before 24 March 2028.
There are two variants:
- Complex buildings (regulation 46A(2)) — commencement is when the foundations supporting that building and the structure of its lowest floor level are completed. A “complex building” means one sharing a foundation plinth or podium with another building or structure, one with more than one storey below ground, or one intended primarily as a public building with capacity for 100 or more visitors.
- Any other building work (regulation 46A(4)) — commencement is when the work identified in the client’s statement as amounting to 15% of the proposed work is completed.
Site clearance, service diversions, roads and sewers, hoarding — none of that gets a plot over the line.
Higher-risk buildings work differently
For HRB work, work to an existing HRB, and stages of HRB work, regulations 6 to 8 use a different mechanism: protection depends on a valid building control approval application having been submitted to the regulator before 24 September 2027 and not being rejected before or after that date. There’s no separate commencement deadline — but a rejection kills the protection, which given Gateway 2 rejection rates is not a theoretical risk. Helpfully, where protection is triggered by an application for a stage of HRB work, it carries through to subsequent stages provided the original application hasn’t been rejected or lapsed.
And the older transitional arrangements are going
Regulation 10 revokes the transitional arrangements in the 2013 Regulations and removes part of the 2021 equivalent, subject to savings. If you have plots that have been sitting under a 2013 saving, they need to be started before 24 March 2028 too, or they fall into the new regime.
What you’re falling into if you miss it
It’s worth being clear about the size of the gap. From 24 March 2027 the amended Part L is retitled “Energy and greenhouse gas emissions”, requirement L1 is rewritten around minimising greenhouse gas emissions as well as conserving fuel and power, and a brand-new functional requirement L3 applies: when a building is erected which is or contains one or more dwellings, a system for on-site renewable electricity generation must be installed on the building or within its curtilage, designed so residents can use the electricity and capable of a reasonable output given the building’s design and surroundings. There are limited exemptions — buildings exempt under regulation 7(4), buildings where a reasonable output genuinely isn’t possible, and cases where an equivalent off-building on-site system already serves the residents.
The definition of “fixed building services” also widens to include lifts, escalators and moving footways in new buildings (excluding those within individual dwellings), and a new regulation 40C requires that information owed to new-dwelling owners under regulations 39 to 40B is actually provided in an appropriate format. Alongside all this sit the new Approved Document L Volumes 1 and 2 (2026) and Approved Document F Volume 1 (2026).
That’s not a tweak. A plot that slips from the old regime to the new one is a redesign, not a re-run of the calculation.
The practical move
Two things are worth doing now:
- Map your plots against both dates, building by building — application in before 24 March 2027, sub-structure complete before 24 March 2028. Any plot where the programme has the ground floor slab landing in early 2028 is a plot at risk.
- Model the FHS case for the plots you know won’t make it, rather than discovering the shortfall late. Fabric, thermal bridging and the L3 renewables requirement all move together, and the cheapest time to find the answer is before the house types are frozen.
If you’d like the Part L and SAP 10.3 modelling done properly — including bespoke PSI values for your junctions rather than defaults that quietly wreck the DER — get in touch and we’ll tell you how we’d approach your scheme.
Sources: The Building Regulations etc. (Amendment) (England) Regulations 2026 (SI 2026/335), legislation.gov.uk · Regulation 46A, The Building Regulations 2010, legislation.gov.uk · The Future Homes and Buildings Standards: Building Circular 01/2026, GOV.UK