With more than 5m properties in England at risk of flooding, Catherine Hill of Peter Cox examines the options for protecting properties from rising waters and how to recover if the worst happens
Winter months are often characterised by heavy rainfall across the UK, with extreme weather sometimes causing flash floods. Storm Bella was the latest to bring serious flood risks to property owners, with the Met Office issuing 112 flood warnings from Cornwall to Kent of potential damage to buildings in December.
Between 10-13 days of rainfall is predicted in the UK across January and February, and with one in six (around 5.2m) properties in England at risk of flooding from rivers or the sea, it’s important those responsible for property maintenance and construction know how to prepare for flood warnings and prevent damage.
Floods can strike quickly and without warning, which means damage can be costly and difficult to repair if the right preparations haven’t been made in time. Damage mitigation is therefore important at this time of year, and that professionals understand where their properties might be at risk.
Resistance vs resilience
For properties in at-risk zones, it is important to assess protection measures before floods occur. These actions fall into two categories: flood resistance or flood resilience measures. Resilience measures look to mitigate and reduce the damage caused by flooding in a property, covering situations where water enters the structure. Resilience measures can be included in a building’s fabric or fixtures, through fittings that can be installed to reduce the consequences and impact of flood water entering the building.
On the other hand, flood resistance measures seek to prevent water ingress by creating watertight barriers to minimise the likelihood of floodwater entering a building and causing damage. This can include both temporary flood resistance products, which require fitting prior to a flood event (such as when a weather warning is in place), or permanent flood resistance products that do not require activating. With the right permanent resistance measures in place, such as waterproof membranes and drainage systems that safely divert water from the property, damage can be prevented.
General design philosophy
Once flood resistance and resilience measures have been taken into account, there’s a common methodology for ensuring no water ingress in a building. This is a combined approach that involves two barrier methods. First, floodwater is excluded from the building using various barrier methods, which are applied to the structure and to points of entry such as doors and service penetrations. These barrier measures, if breached or damaged during a flood event, will be backed up by internal waterproofing methods, which should in any substructure (cellars or basements) comply to BS8102 2009.
In retrofit scenarios, a waterproofing system is often now adopted. These are known as drained protection measures involving hidden cavity drainage membranes, drainage channels, floor gullies and a pump. This means penetrating floodwater will be controlled and diverted behind the membranes and finishes before being pumped out of the building at a faster rate than it can enter the premises.
In case of overtopping, protracted periods of ingress or bypassing of prevention measures, such as leaving a door open inadvertently, the internal finishes are designed to be resistant and “recoverable” quickly. This will protect vulnerable parts of a property – particularly those at lower-ground or below ground levels, where water is most likely to get in and cause lasting damage.
What to do in the event of flood damage
If a property succumbs to flood damage, it can create dangerous situations from an electrical, structural and hygiene point of view. Before clean-up, you should reach out to trained experts to evaluate the affected property and identify all the damage and structural hazards. This allows the clean-up and rebuilding process to take place as efficiently and safely as possible. It’s also worth consulting a qualified electrician, as they can check all the electrics in the building are safe and establish what equipment can safely be used during the clean-up process.
Property experts can help to assess damage to the structure and recommend a course of action for restoring a property to its pre-flood state, while they will also have access to specialist equipment like a pump and generator. Having a clear plan can help to reduce the stress of dealing with the aftermath and ensure restoration takes place before water damage causes timber decay.
Flooding is a fairly common occurrence across the UK and, statistically, a home is more likely to be flooded than burgled so it is incredibly important for both property owners and those in the construction industry to investigate flood protection options.
When a flood does occur, damage can not only be costly and difficult to repair, but it can also be incredibly dangerous and distressing. It’s important to prepare a property as best you can to reduce damage should a flood occur. A proofing combination of effective resilience and resistance measures gives a property the best chance of restoring it to its original state in the most timely and safe manner possible.
National commercial manager
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