2026 is an awkward year for Part L. Two things are true at the same time. You are still building to the standard introduced in the 2021 uplift, in force since June 2022. And the Future Homes Standard, the next revision of Part L, was published in March 2026 and takes effect from 24 March 2027. That leaves site teams doing two jobs at once: keeping today’s documentation watertight while getting ready for a much bigger step up.
For main contractors and site managers, most of the risk sits in the documentation, not the design. A scheme can be specified to pass and still fail on site if the evidence is not captured correctly. Here is what that means in practice.
What you are building to now
The 2021 uplift did two things that changed life on site. It introduced the Building Regulations England Part L (BREL) report, and it made photographic evidence mandatory.
There are two BREL reports. The design-stage report is produced from the SAP calculation before any building work starts, showing the specification has the potential to meet its targets. The as-built report is completed at the end and must be signed by both the SAP assessor and the builder, and it only stands up if the supporting evidence backs it.
That sign-off depends on photographs. Appendix B of Approved Document L1 sets out evidence requirements across six stages of the build: foundations and ground floor, external walls for each wall type, roofs for each roof type, openings, airtightness details, and building services. The photos have to be high resolution, geolocated with location, date and time, and named to a plot and detail reference so an assessor can audit them. The responsibility for capturing all of this sits with the main contractor.
Why Part L still fails on site
The regulation is not the hard part. The evidence trail is.
The volume is the first problem. A single plot needs images at multiple stages, and a stage missed cannot be recreated once the wall is closed up or the floor is poured. Get it wrong and the fix can mean opening up finished work, which delays the EPC, delays the BREL sign-off, and delays completion.
The second problem is the performance gap: the difference between how a home is designed to perform and how it actually performs once built. Insulation left with gaps, thermal bridging at junctions, or airtightness detailing skipped under time pressure all pull as-built performance below the SAP figure. The photographic requirement exists precisely to close that gap, which is why assessors and building control now expect proof rather than assurance.
Manual capture makes both problems worse. Photos taken on personal phones, saved to folders, renamed by hand and emailed in batches are easy to lose, easy to mislabel and hard to audit. When the evidence is disorganised, the assessor cannot sign, and the programme stalls.
What the Future Homes Standard changes
Part L 2026 is the largest change to the standard in decades. New homes will need to produce at least 75% less carbon than one built to 2013 standards, against roughly a 31% improvement under the 2021 uplift. In practice that means low-carbon heating, with heat pumps as the default, solar PV as standard, tighter fabric and a lower airtightness limit. Compliance will be assessed through SAP 10.3 first, with the Home Energy Model to follow.
For documentation, the direction of travel is clear. More systems in every home means more to install correctly and more to evidence. The new rules also strengthen handover: information passed to building owners must be provided in an accessible, usable format, not simply filed. The teams that treat evidence as an afterthought today will feel that shift most in 2027.
The dates matter for planning. The standard applies to new residential submissions from 24 March 2027, to higher-risk buildings from 24 September 2027, and to any plots not started by 24 March 2028. Any scheme entering design now is likely to be delivered under it.
Getting the evidence trail right
The practical lesson is the same for both regimes. Part L compliance is won or lost by whether the right evidence is captured, at the right stage, by the right person, and kept somewhere an assessor can trust.
That is where digital site tools earn their place. Capturing geolocated, time-stamped photographs against each plot as work happens, rather than reconstructing a folder at the end, removes most of the risk. PlanRadar gives site teams a single place to record inspection evidence, tie it to the exact location and stage, assign follow-ups where a detail is missing, and produce a clean, auditable record for the assessor and the building owner. And our AI features can also help teams surface gaps in that record before they reach sign-off.
Part L is only going to ask for more proof, not less. The contractors who tighten their evidence process now will find 2027 far less painful than those who wait.
Click the link below to book a demo and find out how PlanRadar can help you tighten your evidence process and tackle Part L.
