If you’re planning a new extension, conversion or replacement dwelling in North Somerset, there’s a high chance you’ll need a Flood Risk Assessment (FRA).
Large areas of the district fall within modelled tidal and fluvial flood zones, and the council’s own planning map shows extensive areas affected by both current and future flood risk.
Because of this, most planning applications in North Somerset require an FRA, even for relatively small domestic projects.
At Gibson Architecture, we are well‑regarded for the quality and success of our Flood Risk Assessments. We provide them either independently or as part of our full planning package.
Why Flood Risk Assessments Are Needed in North Somerset
North Somerset Council’s Planning Map includes detailed flood layers showing:
- Existing tidal flood risk
- Modelled future tidal flood risk
- Fluvial (river) flood risk
- Surface water flood risk
- Climate change allowances
These layers demonstrate that many communities (including Weston‑super‑Mare, Uphill, Worle, Wick St Lawrence, Banwell, Congresbury and the coastal belt) fall within areas of elevated flood risk.
Because of this, the council routinely requires an FRA for:
- Extensions
- Replacement dwellings
- New dwellings
- Barn conversions
- Outbuildings
- Changes of use
- Prior Approvals in flood zones
Even small domestic extensions can trigger the requirement.
When a Flood Risk Assessment Is Required
You will need an FRA if your site is:
1. In Flood Zone 2 or Flood Zone 3
This includes both tidal and fluvial flood zones.
2. Over 1 hectare in size
Even if in Flood Zone 1.
3. At risk from surface water flooding
North Somerset has extensive surface water risk areas.
4. Affected by climate‑change modelled flood levels
Future tidal modelling often extends far inland.
5. Within a Critical Drainage Area
These areas require additional drainage considerations.
6. A change of use to a more vulnerable category
E.g., converting a barn into a dwelling.
7. A replacement dwelling
Even if the footprint is similar.
If you’re unsure, we can check the flood layers and confirm your requirements quickly.
What a Flood Risk Assessment Includes
A professional FRA typically covers:
1. Site Levels & Topography
Existing ground levels, finished floor levels and surrounding landform.
2. Flood Zone Classification
Tidal, fluvial, surface water and groundwater risk.
3. Modelled Flood Levels
Including future climate change allowances (often 2080–2125).
4. Flood Depth & Hazard Analysis
How deep water could get and how hazardous it would be.
5. Safe Access & Egress
Whether occupants can safely leave the site during a flood.
6. Mitigation Measures
Such as:
- Raised floor levels
- Flood‑resilient construction
- Raised electrical sockets
- Non‑return valves
- Resilient materials
- SUDS drainage strategies
7. Sequential & Exception Test Commentary
If required (we can prepare these too).
8. Drainage Considerations
Surface water management, infiltration potential and discharge rates.
Our FRAs are detailed, clear and tailored to the specific risks of each site.
Do I Need the Sequential or Exception Test?
Most householder extensions do not require the Sequential or Exception Test.
However, you may need them if:
- You are proposing a new dwelling
- You are intensifying use (e.g., converting a barn to a house)
- You are building a replacement dwelling in Flood Zone 3
- The council specifically requests them
We can prepare these tests where required.
How Much Does a Flood Risk Assessment Cost?
Typical costs depend on:
- Size of the development
- Flood zone
- Complexity of modelling
- Whether Sequential/Exception Tests are required
For most domestic projects in North Somerset:
Typical FRA cost:
£350 – £650
(Standalone or included within our planning package)
Sequential/Exception Tests are additional if required.
H2: How Long Does an FRA Take?
Most FRAs can be completed within:
5–7 working days
More complex sites (e.g., replacement dwellings in Zone 3) may take slightly longer.
H2: Why Choose Gibson Architecture for Your FRA?
We are known locally for:
- Clear, robust and well‑structured FRAs
- High success rates with North Somerset Council
- Fast turnaround times
- Accurate interpretation of modelled flood data
- Practical mitigation strategies
- Integration with planning drawings and design
We can provide FRAs:
- Independently, if you only need the assessment
- As part of a full planning package, including drawings, design and submission
This ensures your application is comprehensive, compliant and ready for approval.
Thinking About a Project in a Flood Zone?
If your property falls within a flood‑affected area, and most in North Somerset do, we can help you understand the risks and prepare a compliant, high‑quality Flood Risk Assessment.
Get in touch:
01934 805987
gibsonarchitecture.co.uk
Weston‑super‑Mare, North Somerset
