New build compliance: what you need at each stage

Published 23 September 2026 — reviewed against the regs as they stand.

Quick answer: A new dwelling in England needs, in order: planning, which may ask for an energy statement, a nutrient neutrality assessment and the 110-litre water standard; before work starts, the design-stage SAP and BREL report with the Part O overheating assessment; during the build, photographs of the insulation and a water calculation before the sanitaryware is ordered; before completion, an air test on every dwelling and sound tests on attached ones; and within five days of completion, the as-built SAP, the completion BREL, the EPC and the Part G notice. The completion certificate waits for all of them.

The whole sequence on one page

The rest of this page takes each stage in turn.

1. Feasibility: before anyone draws it properly

Three things about the site can each add a report and a cost. It’s much better to know them before the land price or the layout is fixed.

• Is it in a nutrient neutrality catchment? If it is, the planning authority can’t grant permission until a nutrient budget shows the scheme adds no nitrogen or phosphorus to the protected water, and that usually means buying credits. The NutrientMonkey calculator gives you the budget free.
• Will planning impose the 110-litre standard? The tighter 110 litres per person per day water standard, instead of the default 125, is triggered by a condition on the planning permission, and councils in water-stressed areas commonly impose it. The water-stressed areas reference explains how to tell.
• What does the local plan say about energy? Many councils want a percentage cut in energy or carbon from renewables. A growing number set energy use intensity and space heating targets that standard SAP can’t demonstrate and need PHPP modelling.

2. The planning application

Planning deals with local policy, not Building Regulations. Where local policy calls for it, you’ll need an energy statement showing how the scheme meets the council’s renewables or carbon target. In an affected catchment you’ll need a nutrient neutrality assessment, prepared to Natural England’s methodology. In London, the London Plan adds its own carbon target on top of Part L.

The energy statement is modelled in SAP, so doing it properly now gives you a head start on the design-stage calculation later.

3. Discharging the pre-commencement conditions

Energy and water requirements are often attached to the permission as conditions, and some of them are pre-commencement: they must be discharged before any work starts. Read the decision notice carefully. “Prior to commencement” means exactly that, and work begun without discharging it is unauthorised. Typical ones are a detailed energy statement, confirmation of the 110-litre water standard, and, in a nutrient catchment, proof that the mitigation credits are secured.

4. The Building Regulations application

This is where most of the calculation work happens, and the cheapest point to change the answer.

• Design-stage SAP. The dwelling has to beat its target rates for carbon and primary energy and its fabric energy efficiency target, and meet the limiting values. The Part L guide explains the four tests. A design that fails now can be fixed by changing the specification on paper.
• Part O overheating. Every new home needs either the simplified method or a TM59 model. The Part O guide shows which. Glazing is the usual problem, and it’s far easier to reduce before the windows are ordered.
• The fabric and the junctions. Wall, floor and roof U-values and the junction psi-values are what the SAP runs on. Calculated junctions instead of default ones are often the cheapest way to close a SAP gap.

5. Before work starts

The regulations fix one deadline here. The target rates, the as-designed rates and the list of specifications the calculation depends on must be notified to Building Control by the day before work begins, on the design-stage BREL report.

Two other things belong here:

• Robust Details. If you’re building attached homes and want to avoid pre-completion sound testing, the plots must be registered with Robust Details Ltd before work starts, and the separating walls and floors built exactly to the registered detail. Details are on the sound testing page.
• A predicted energy assessment if the homes will be marketed off-plan. It comes from the design-stage SAP.

6. During construction

This is the stage people think needs nothing from the assessor, and it’s where most completion problems start.

• Photographs. Every dwelling needs its own set of photographs of thirteen insulation, airtightness and services details, taken before each one is covered. The photographic evidence guide has the list and a printable plot checklist.
• The water calculation. Do it before the bathroom and kitchen fittings are ordered. Many specifications pass by only a litre or two, so a larger bath or a higher-flow shower can tip it over. WaterMonkey checks a fittings schedule free.
• Specification changes. A different window, heating system or insulation product usually saves money for someone. Every change has to be reported at the as-built stage and the SAP re-run, and some turn a pass into a fail. Ask before the substitution is ordered, not after it’s fitted.

7. Pre-completion testing

• Air tightness. Every new dwelling is tested once the envelope is complete and sealed. The result goes into the as-built SAP, so a test worse than the design assumption can fail a plot that passed on paper. The pre-test checklist covers the usual leaks.
• Sound. Attached homes need airborne and, where there are separating floors, impact sound tests, unless they’re registered under Robust Details. Tests happen once the rooms on both sides are finished. How many tests you need depends on the number of plots and their construction types.

Book both early. Each test needs the building in a particular state, and a failed test has to be remediated and retested before completion.

8. Completion: the five-day window

Within five days of completion:

• The as-built SAP results and any specification changes go to Building Control on the completion-stage BREL report, signed by the assessor and the builder, with the photographic evidence.
• The EPC is lodged from the as-built SAP and given to the owner.
• The Part G water notice goes to Building Control under Regulation 37. The water calculation guide explains what it must say.
• The home user guide goes to the occupier.

Building Control can’t issue the completion certificate without these, and without the certificate the sale can’t complete. Five days is the legal backstop, not a target. Most of what goes in the completion pack can be prepared as the build progresses, so the window is used for signatures rather than chasing.

Commercial buildings follow the same shape

A building other than a dwelling runs on the same pattern with different paperwork. SBEM replaces SAP, and the BRUKL report replaces the BREL: one before work starts, one within five days of completion. The non-domestic EPC is lodged from the as-built model, and the air tightness limit is the same. Planning can still ask for an energy statement or BREEAM, depending on the council.

Conversions and extensions are shorter

• A conversion that creates a new dwelling needs SAP, the Part G water calculation and an EPC, but not the new-build target rates, the photographs or Part O. See SAP for conversions.
• An extension usually needs no SAP at all, provided it meets the limiting U-values and its glazing stays within 25% of the floor area. GlazeMonkey checks the 25% rule, and the extension guide covers what to do when it fails.

The bottom line

Nearly every late-stage compliance problem is an earlier stage that got skipped. The fixes that are free on a drawing cost scaffolding and plaster once the house is up. If you tell us where your project has got to, we’ll tell you what it still needs. The New Build Compliance Pack covers the SAP, EPC, water, air and sound testing as one job with one set of assumptions.