Building standard 3.3 - flooding and groundwater guidance review: research

Executive Summary

1. The current Scottish Government Building Standards include provisions on flood risk assessment and mitigation within their published Domestic and Non-domestic Technical Handbooks (2022). 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 groundwater”. The purpose of this study was to inform the review of guidance which supports Standard 3.3, including identifying current good practice on flooding and groundwater and suggesting improvements and adoption for those matters moving forward.

2. This 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 responses from industry professionals.

3. The online 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 and the strong steer in National Planning Framework 3 and 4 towards the avoidance of flood risk.

4. 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, flood and planning officers rarely work together), viewing SEPA maps, flood risk assessment report (noting that a flood risk assessment is usually undertaken at the planning stage), site investigation report and involvement of local authority structural engineers. The most common matters which are checked are development location, finished floor level and drainage. The Building Standards Technical Handbooks were identified as the documents most commonly used for verifying compliance, supporting an update to those Handbooks. A potential need for training on flood risk and PFR in particular was also noted.

5. One of the key good practice findings of the literature review was the CIRIA publication ‘Code of practice for property flood resilience’ C790 (2nd Edition). C790 is a key reference suite of four guides for PFR, which could be integrated into the building warrant verification process, including site inspection. A suggested good practice approach for this, together with checking compliance for other flood mitigation measures such as development location and finished floor levels are included within this report.

6. It is recommended that this good practice approach should be included in an annex supporting the guidance in section 3.3 of the Technical Handbook. Additionally, consideration to 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 and also promotion of greater interdepartmental working on flood risk (e.g. across building standards, planning and flood officers).

7. Lastly, it is noted that the PFR code of Practice has requirements for post installation audit and whilst this is embedded within grant structures in England, installation relies more on property owners in Scotland and therefore the post installation audit may be beyond the remit of Local Authorities and could be overlooked.