The Future Homes Standard includes transitional arrangements to give the building industry time to adapt. These arrangements determine which homes can be built to current Part L 2021 rules and which must meet the new FHS requirements. Getting the transitional timeline right is critical for developers — it affects procurement, design, cost planning, and land strategy.
Timeline Overview
The transitional timeline has three key phases:
| Phase | Expected Date | What It Means |
|---|---|---|
| FHS regulations laid | 2026 | Final regulations published and laid before Parliament |
| FHS comes into force | Late 2026 | New building control submissions must comply with FHS (unless transitional relief applies) |
| Transitional period | Late 2026 – Late 2027 | 12-month window for pre-registered plots to commence under Part L 2021 |
| Hard deadline | Late 2027 | ALL new homes must comply with FHS, regardless of registration date |
| Full enforcement | January 2028 onwards | No transitional relief available — FHS is the universal standard |
How the Transitional Arrangements Work
Individual Building Basis
The FHS transitional arrangements operate on an individual building basis, not site-wide. This is a crucial distinction and represents a stricter approach than some previous Building Regulation transitions.
On a large development site, different homes may fall under different regulations:
- Plots registered and commenced before the transitional deadline → Part L 2021
- Plots registered before but not commenced within the transitional period → FHS
- Plots registered after the FHS comes into force → FHS
This means developers cannot simply register an entire site before the deadline and then build all homes to the old standard over several years. Each individual home must have commenced within the transitional window.
What “Commence” Means
The definition of “commence” under the proposed transitional arrangements is broader than just starting the superstructure. Commencement includes:
- Drainage work — installation of below-ground drainage
- Foundation work — excavation and pouring of foundations
- Substructure — ground floor slab and below-ground construction
Activities that do not count as commencement:
- Site clearance and demolition
- Earthworks and land levelling
- Installation of site hoarding or temporary facilities
- Utility diversions or enabling works
- Planning or building control applications alone
The Registration Process
To qualify for transitional arrangements, a building must have a building control application (either an initial notice to an approved inspector or a full plans application to the local authority) submitted and accepted before the FHS comes into force.
The application must be for a specific building — outline or batch submissions covering unspecified future plots will not qualify. This means developers need detailed designs and SAP assessments ready for each plot they wish to register.
The Expected Registration Surge
Previous Building Regulation transitions (notably the 2021 Part L uplift) saw a significant surge in plot registrations in the months before the new standards came into force. The FHS transition is expected to trigger an even larger surge because:
- The cost differential between Part L 2021 and FHS is larger (3–5% additional build cost)
- FHS requires fundamentally different heating systems (heat pumps instead of gas boilers), not just incremental improvements
- Supply chain readiness for heat pumps and MVHR at the required scale is uncertain
- Developers have commercial incentive to maximise the number of plots that can be built to the lower-cost standard
This surge will strain building control capacity. Developers should:
- Engage building control early — capacity constraints mean lead times for application processing will increase
- Have SAP assessments ready — applications need to demonstrate Part L 2021 compliance at submission
- Prioritise high-value plots — focus transitional relief on plots where the cost saving is greatest
Strategic Considerations for Developers
Dual Design Strategy
Many developers will need to run parallel house type designs — Part L 2021 versions for transitional plots and FHS versions for post-transition plots. Key considerations:
- House type re-engineering — FHS homes need heat pump plant rooms (or external units), MVHR duct routes, thicker wall builds, and space for hot water cylinders. These are not minor modifications
- Foundation design — FHS floor U-values may require deeper insulation, affecting foundation design and construction sequencing
- Plot-level decisions — on mixed-regulation sites, careful sequencing is needed to avoid construction conflicts between Part L 2021 and FHS plots
Procurement and Supply Chain
The transition creates acute supply chain pressure:
- Heat pumps: UK demand will spike sharply as the deadline approaches. Early procurement and framework agreements with manufacturers are critical
- MVHR units: Specialist product with relatively few UK suppliers. Long lead times expected as demand increases
- Solar PV: Panels are widely available, but installer capacity for the volume of new-build installations may be constrained
- Triple glazing: UK manufacturing capacity is growing but may not match immediate demand. European imports fill the gap but add lead time
- Skilled labour: Heat pump installation, MVHR commissioning, and enhanced airtightness detailing require trained operatives — a workforce gap that takes time to fill
Cost Planning
The government estimates FHS adds 3–5% to build costs over Part L 2021. However, cost impacts vary by house type:
| Factor | Cost Impact | Notes |
|---|---|---|
| Heat pump (ASHP) | £3,000–£5,000 net uplift | vs gas boiler. Price gap narrowing as heat pump volumes increase |
| MVHR system | £2,000–£4,000 | Unit, ducting, commissioning. Design-stage integration reduces cost |
| Solar PV (typical 3–4 kWp) | £4,000–£6,000 | Panel, inverter, installation. Costs falling year-on-year |
| Enhanced insulation | £1,000–£3,000 | Thicker walls, triple glazing uplift, improved floor/roof insulation |
| Airtightness detailing | £500–£1,500 | Membranes, tapes, careful detailing. Lower with factory-built systems |
| Hot water cylinder + pipework | £500–£1,000 | Required for heat pump systems (no combi equivalent) |
These costs should be weighed against lower running costs for FHS homes (40–50% lower energy bills), which will become a marketing advantage and may support higher sale prices as energy efficiency becomes more prominent in buyer decisions.
Sales and Marketing
The transition creates an opportunity for developers who move early:
- Energy bill savings — FHS homes with heat pumps and solar PV will have significantly lower running costs than both existing stock and Part L 2021 new builds
- EPC ratings — FHS homes will achieve excellent ratings under the new HEM-based EPCs, differentiating them from older stock
- Future-proofing — zero carbon ready homes will not need retrofitting as the grid decarbonises
- Mortgage advantage — some lenders offer preferential terms for energy-efficient homes, and this trend is expected to strengthen
Compliance Methodology During Transition
The methodology picture was clarified in February 2026: SAP 10.3 is the sole compliance methodology at FHS launch, with HEM following at least three months later and a 24-month dual running period once both are available. This simplifies the early transition:
- Part L 2021 plots (under transitional relief) use SAP 10.2 for compliance, as they do today
- FHS plots at launch use SAP 10.3 only — HEM is not available
- FHS plots after HEM approval (3+ months after FHS launch) can use either SAP 10.3 or HEM via the ECaaS platform
- After dual running ends (24+ months after HEM approval), HEM becomes the sole FHS compliance route
On a mixed-regulation site, assessors may work with multiple compliance tools. For more detail on the methodology routes, see our Compliance Pathways page and our analysis of the SAP 10.3 confirmation.
Building Control Considerations
The transition affects building control processes in several ways:
- Increased application volumes before the deadline will strain both approved inspector and local authority building control capacity
- Mixed-standard sites require building control officers to verify which regulation version applies to each individual plot
- New competency requirements — building control bodies will need familiarity with HEM outputs and ECaaS documentation
- The Building Safety Regulator (BSR) under the Building Safety Act may introduce additional oversight requirements for FHS compliance
Frequently Asked Questions
When must new homes comply with the Future Homes Standard?
The FHS is expected to come into force in late 2026, with a 12-month transitional period ending in late 2027. After that hard deadline, all new homes must comply. These dates depend on the government response to the 2023 consultation being published in early 2026. See our Timeline page for the latest position.
What does “commence” mean under the transitional arrangements?
Commencement includes drainage and foundation work — not just superstructure construction. Site clearance, earthworks, hoarding, and enabling works alone do not count. Each individual building must have started meaningful physical construction.
Do the arrangements apply site-wide or per building?
Per building. This is stricter than some previous transitions. On a large site, some homes may fall under Part L 2021 and others under FHS, depending on when each was registered and commenced.
Can I register plots early to use the old regulations?
Yes, plots registered before the FHS comes into force can benefit from transitional relief. But registration alone is not enough — you must also commence construction within the 12-month transitional window. Expect a surge in registrations that will strain building control capacity.
What happens after the transitional period ends?
After the hard deadline (expected late 2027), all new homes must comply with FHS regardless of when they were registered. There are no further extensions or grandfather clauses. Unstarted registered plots that miss the commencement deadline must meet the new standards.
Related Pages
Future Homes Standard Overview
Complete guide to FHS requirements, timeline, and who it affects.
Compliance Pathways
HEM vs SAP 10.3 routes and how to demonstrate FHS compliance.
Part L Changes
Fabric specifications, heating requirements, and the notional dwelling.
EPCs & HEM
How Energy Performance Certificates are changing under HEM during the transition.