Flood resilient construction
Flood barrier. Reproduced with permission from Befloodready.uk
Buildings at direct flood risk can be adapted or retrofitted with measures that can help reduce the impact of flood events, or even to prevent a flood from occurring.
In recent years there has been a range of guidance documents and websites published providing further information on the steps that can be taken to make properties more resilient to flooding. Several of these are outlined below.
There are two types of approaches: flood resistance and flood resilience.
Property Level Resistance
Resistance measures are designed to, as far as possible, keep flood water out of a property (dry-proofing), or to slow the rate of water ingress. Specific measures include aperture barriers (door and window boards), flood resistant doors and air brick covers.
Garage aperture barrier. Reproduced with permission, Phil Emonson, JBA consulting.
To be effective, measures need to be used in conjunction with each other to ensure every water ingress point is properly and fully protected. Measures also require careful attention to the upgrading and maintenance of the building fabric to ensure water resistance is complete.
For instance, brickwork pointing might need to repaired, and holes for wiring and cables will require sealing with silicone or a similar water resistant material. Additionally, attention needs to be paid to adjoining properties to ensure they too resist water.
Consequently, the integration of measures requires careful surveying, planning and skilled procurement and installation to ensure flood resistance standards are met.
Resistance products can be either permanent, always in place and not requiring activation, or temporary requiring installation or activation in advance of a flood or when a warning is received.
Above a certain threshold, it is recommended that water should be allowed to overtop barriers to ensure floodwaters do not cause structural damage or increase the risk of building collapse. Buildings can usually be protected to a water depth of 600mm.
Property Level Resilience or Repairability
In contrast, resilience measures are installed under the assumption that water will enter a property, but that interventions and modifications will seek to minimise damage.
This wet-proofing allows a property to be reinstated and reoccupied as quickly as possible after a flood. It might include the integration of surfaces that can be cleaned, sanitised and dried after a flood (hardstanding floors or stainless steel kitchens). It may also include sacrificial surfaces that can easily be removed and replaced. Consequently, the terms repairability and recoverability are sometimes used in conjunction with resilience.
Other measures might include ensuring electrical points are raised above water ingress levels, upgrading electrical networks and installing water pumps to assist with post-flood recovery.
Resilience measures usually involve alterations to the fabric and fixtures and fittings of a property. Given this, the immediate aftermath of a flood event, when a property is being stripped out and refurbished, is considered to present a prime ‘window of opportunity’ to integrate resilience measures.
Other approaches to creating flood resilient buildings
There are other approaches to living with flood risk. Although relatively uncommon in the UK, properties can be designed to rise and fall with water levels. These are referred to as amphibious buildings. Some building owners have converted the lowest flood of their properties into spaces that can be easily cleared in advance of a flood, and have concentrated living on the first floor and above. In one instance in Northumbria, an existing property was raised on stilts for this purpose, whilst a store in flood prone Mytholmroyd received permission to build on stilts.
What does a future-proofed home look like? - BBC News What does a future-proofed home look like? - BBC News
Sources of further information and guidance
Six Steps to Flood Resilience
The Six Steps to Flood Protection documents offer a step by step approach and easy to understand guidance for what to consider at the various stages of property protection purchase, installation and operation.
There are two versions of this document:
To download the six steps guidance for property owners, please click here.
To download the six steps to flood resilience document that has been designed for local authorities and professions, please click here.
The steps are very briefly summarised below.
Step 1
Understand the Risk
Knowing the level and source of your risk is important in order to make a decisions on how to protect your property.
Step 4
Design and Specification
The survey will recommend a combination of products. Check that these are right for you and your circumstances.
Step 2
Planning a Scheme
Find out what types of products are available and how they might be funded.
Step 5
Product Installation
Some manufacturers install their own products. Others will be installed by a third party.
Step 3
Property Surveying
The next step is a survey of your property, including a check for all possible points where water can enter.
Step 6
Maintenance and Operation
All products – even automatic ‘fit-and-forget’ ones – will need to be periodically maintained.
BRE Flood Resilient House
The BRE Flood Resilient Repair Home aims to show alternative replacement products in repairs to a flood damaged house that will not be affected by subsequent flooding; products that are resilient.
It also shows how simple measures such as placing electrical outlets higher up walls and using doors and windows with flood resisting seals can help minimise future damage. And, if water does get in, an automatic ‘sump pump’ connected to drains in the floor quickly gets water out of the house again.
Further information on the demonstration house can be found on the BRE website.
BeFloodReady
BeFloodReady provides guidance and information on Property Flood Resilience (PFR), helping homes, businesses and communities to be better prepared for flooding.
The website is available here: https://www.befloodready.uk/
BeFloodReady also has a Youtube channel with useful demonstrations of resistance and resilience measures available.
The Flood Hub
The Flood Hub has been designed to be a one stop shop for flood information and resources to support householders, businesses and communities across the North West in becoming more flood resilient.
Information about Property Flood Resilience on the Flood Hub website
The National Flood Forum Blue Pages
The National Flood Forum is a charity that was established to help, support and represent people at risk of flooding.
The National Flood Forum Blue Pages is a directory of property flood products and services. Different categories of flood products and services are searchable. Where applicable, the relevant standards or criteria that should be met is also detailed.
Find our more on the National Flood Forum Blue Pages website
The Property Flood Resilience Action Plan
The Property Flood Resilience Action Plan details a strategy for enabling better uptake of resilience measures for properties at high flood risk.
Ciria Code of practice for property flood resilience
A Code of Practice (CoP) was developed to set the benchmark for those installing or constructing PFR. It details six standards specifying what should be achieved when delivering PFR. Supporting guidance was also produced to explain how the standards could be met and explains how a six staged process aligned with the standards complies with the CoP and follows good practice
The code is accompanied by guidance documents, including a fact sheet on the code of practice for households and businesses (C790c) and guidance for planners on how the Code of practice can be applied (C790d).
The Code of Practice, and further supporting documents can be downloaded from the Ciria website.
