Building standard 3.3 - flooding and groundwater guidance review: research

5. Conclusions and recommendations

Conclusions

5.1 Building Standard 3.3 "Flooding and groundwater" requires that “every building must be designed and constructed in such a way that there will not be a threat to the building or the health of the occupants as a result of flooding and the accumulation of ground water”. The purpose of this study was to inform the review of guidance which supports Building Standard 3.3 and had the following specific aims:

• To identify and develop good practice that can be used by verifiers when assessing building warrant applications against building standard 3.3 - Flooding and groundwater, including improving the cohesion of flood risk assessment and mitigation across the planning and building warrant application processes.
• To identify the current guidance and practices used by the flood industry when designing dwellings and buildings to mitigate flood risk by incorporating flood resistance and recoverability techniques and products into building design.

5.2 An understanding of current practice and guidance was achieved via a literature review and online survey targeted at eight Local Authorities covering rural, urban and city areas (Aberdeenshire Council, Angus Council, Argyll and Bute Council, Clackmannanshire Council, City of Edinburgh Council, Highland Council, Orkney Islands Council, Scottish Borders Council) with additional response from industry professionals within JBA Consulting.

5.3 The survey identified that flooding and groundwater issues are almost always dealt with at the planning stage by planning and flooding officers, and, likely because of this process, it is much rarer for building standards officers to become involved on these topics. Comparatively few building standards officers check for compliance on flood risk matters, and when they do, Property Flood Resilience (PFR) almost never features, perhaps because of its (to date) limited uptake in Scotland. Where compliance is checked, there was no single approach taken across the Local Authorities surveyed. Approaches included: involving the flood officer (although it was noted that building standards and flood and planning officers rarely work together), viewing SEPA maps, flood risk assessment report (note that a flood risk assessment is usually undertaken at the planning stage), site investigation report and involvement of LA structural engineers. The most common matters which are checked are development location, finished floor level and drainage. The Building Standards Technical Handbook was identified as the document most commonly used for checking compliance, supporting an update to that Handbook. A potential needing for training on flood risk and PFR in particular was also noted.

5.4 From the literature review, a thematic analysis of the literature showed that flood protection measures include:

• Elevate the building on land.
• Elevate the building (up to 2m).
• Elevate the building (over 2m).
• Use of perimeter protection.
• Make it flood resistant (dry-proof).
• Make it flood recoverable (wet-proof).
• Make the building movable/temporary.
• Amphibious building.
• Design building to float.
• Self-elevating (jack-up) building/barge.
• Design building to be transitional.

5.5 Many of these measures fall into the category of PFR. CIRIA publication ‘Code of practice for property flood resilience’ C790 (2nd Edition) has recently become a key reference suite of four guides for PFR and this could be integrated into the Building Warrant and Completion stages of the building standards process, including site inspection. Table 4-1 and Table 4-2 in the preceding section provides a suggested approach as to how this could be achieved.

Recommendations

5.6 The following recommendations are made:

• Incorporate good practice on compliance on flooding and groundwater issues in an annex supporting the guidance in section 3.3 of the Technical Handbooks. This should include from Building Warrant assessment through to Completion stage and should include items such as development location, finished floor level and (where used) use of PFR.
• Clarify how section 3.3 builds on the planning process and can also address the same issue in some situations where the planning process does not.
• If PFR does become more widespread in Scotland, then consider options for further educating building standards officers in order to allow them to check compliance competently. Options could include expanded guidance, resources, Continuing Professional Development and training.
• Promote more cross department working on flood risk (e.g. across BS, planning and flood officers).