BREEAM Flood Risk Assessments Explained

BREEAM is the leading sustainability standard for UK buildings, and how a scheme handles flood risk is one of the things it scores. A BREEAM flood risk assessment is a site-specific study of a development's flood risk, written so the findings can support the relevant BREEAM credits, chiefly Pol 03, Flood and surface water management. It draws on much the same evidence as the flood risk assessment you submit for planning, but it answers to the BREEAM assessor rather than the planning authority, and confusing the two is where projects lose credits or pay for the same work twice. This guide explains what a BREEAM FRA covers, which credits it supports, how it differs from a planning FRA, and when to commission one. If you already know you need one, our flood risk assessment for BREEAM service is the place to start.

A BREEAM flood risk assessment uses much the same evidence as a planning FRA, but it is scored by the BREEAM assessor against Pol 03 — not by the planning authority against the NPPF.

• Site-specific study. A BREEAM flood risk assessment establishes a development's flood risk so the findings can support BREEAM credits, mainly Pol 03 (Flood and surface water management).
• Same data, different marker. It uses much the same evidence as a planning FRA, but a planning FRA answers to the NPPF and the Environment Agency, while a BREEAM FRA answers to the BREEAM assessor.
• Pol 03 has three parts. Flood risk, surface water run-off (benchmarked to The SuDS Manual, CIRIA C753) and reducing watercourse pollution.
• Commission it early. Around RIBA Stage 2, so mitigation is designed in rather than retrofitted and credits are not lost.
• Avoid paying twice. A well-prepared planning FRA usually provides most of the evidence a BREEAM assessment needs.

What is a BREEAM flood risk assessment?

A BREEAM flood risk assessment is a site-specific study that establishes a development's flood risk and shows how the design responds to it, prepared so the findings can support the relevant BREEAM credits. It looks at every source of flooding that could reach the site and at how those risks change over the building's lifetime.

That means rivers and the sea, surface water, groundwater, sewers and artificial sources such as reservoirs or canals, and how climate change shifts each of them across the building's design life. It also weighs the development's own effect on run-off, and whether the scheme could increase flood risk for neighbours. It is assessment work, in other words, not a desk check against a published map.

Which BREEAM credits does flood risk affect?

Flood risk sits in BREEAM's pollution category, under the credit Pol 03: Flood and surface water management, in BREEAM UK New Construction 2018 and Version 6. The credit is often described loosely as just "surface water run-off", but Pol 03 is broader than that, and it has three distinct parts.

1. Flood risk. Credits for siting and designing the development so flood risk to the building and its users stays low, judged against the site's flood zone. Where a site spans more than one zone, BREEAM takes the worst case.
2. Surface water run-off. Credits for keeping post-development run-off rates and volumes at or below the pre-development position, benchmarked against The SuDS Manual (CIRIA C753).
3. Minimising watercourse pollution. Credits for measures that reduce the pollution carried by surface water leaving the site.

Flood-resilient design can also support BREEAM's climate-change adaptation credit (Wst 05 in New Construction 2018), because safe finished floor levels and resilient construction speak directly to a building's long-term resilience. The exact credit references, thresholds and available points depend on the BREEAM scheme and version you are certifying under, so always confirm them against the relevant BREEAM scheme manual.

Where a site is protected by existing flood defences, Pol 03 can still award flood-risk credits — but only where the relevant agency confirms the defences reduce the risk to low or medium, and the land was previously developed.

How does a BREEAM FRA differ from a planning FRA?

A planning FRA is driven by the National Planning Policy Framework (NPPF) and Planning Practice Guidance, and it has to satisfy the local planning authority and the Environment Agency. A BREEAM FRA is scored against the scheme's Pol 03 criteria instead. The underlying work overlaps so heavily that the two are easy to confuse, which is exactly how the duplication creeps in.

The trigger for a planning FRA is set out in government planning guidance, and it is worth knowing where it bites before assuming a BREEAM project needs a separate report.

That overlap is the practical point. The same understanding of the site's flood zone, the same assessment of all flood sources, and the same surface water drainage strategy can serve both purposes when the work is set up with both in mind. A well-prepared planning FRA usually supplies most of the evidence a BREEAM assessor needs; see our guides on how to do a flood risk assessment and why expertise matters in an FRA. Done separately and late, it is where projects pay twice.

When should you commission a BREEAM flood risk assessment?

Early. To give yourself the best chance of the Pol 03 credits, the flood-risk work wants to be done while the layout is still flexible, ideally around RIBA Stage 2 (concept design). That is the point at which sustainable drainage, attenuation and sensible finished floor levels can be built into the scheme rather than bolted on afterwards. Leave it until detailed design or later and you risk losing credits, redesigning the drainage, or both.

The flood-risk credits available under Pol 03 are capped by the site's pre-development flood risk, before any mitigation — which is why the classification is worth establishing early.

Assessing early is usually cheaper too, which is the same lesson as the wider question of what an FRA costs: the work is far less disruptive when it shapes the design than when it has to correct one.

What a BREEAM flood risk assessment looks at

The scope mirrors a thorough planning FRA, then reads it against the credit criteria. In practice a BREEAM flood risk assessment covers the following.

• Flood zone and all sources. The site's flood zone and its risk from every source, taking the worst-case zone where a site spans more than one.
• Finished floor levels and resilience. Proposed finished floor levels and flood-resilience measures, set as they would be for a planning FRA.
• Surface water strategy. The surface water drainage strategy and post-development run-off rates and volumes, tested against the C753 benchmark and the SuDS hierarchy.
• Climate change. How climate change shifts the risk across the building's design life.
• Evidence for Pol 03. That the design meets the relevant Pol 03 thresholds for the scheme version.

How Unda can help

Unda prepares flood risk assessments that work for both planning and BREEAM, so you are not paying twice for overlapping work, and we coordinate with your BREEAM assessor so the available Pol 03 credits stay within reach. The detail, the scheme-version specifics and the quoting all live on our flood risk assessment for BREEAM service page, and where a scheme also needs to clear planning we can fold it into a single flood risk assessment for planning.

If you have a BREEAM project, the most useful next step is to arrange a flood risk assessment for BREEAM or talk to our flood risk consultants about it.