Renovating a House in a Flood Zone
Are you considering purchasing or renovating a property located in a flood risk area? While the price can appear advantageous, it’s important to be aware of the potential risks to your home, and the specific concerns to take into consideration if you plan to renovate a property in a flood zone. From planning permission and insurance to design and construction strategies, here's what you need to know to make sure you're prepared.
What’s a flood zone?
As many as 1 in 6 properties in England are subject to a significant risk of flooding, whether from rivers, reservoirs, surface water, the sea or other sources. While no area is completely free of the risk of flooding, it’s particularly important for owners of properties in moderate- or high-risk flood areas to be prepared and understand how these risks can be managed. In the UK, flood zones are defined in three categories. Flood Zone 1 refers to land identified as having an annual probability of less than 1 in 1,000 (under 0.1%) of river or sea flooding, making it a low-risk area. Flood Zone 2 refers to moderate-risk areas assessed to have up to a 1% chance of river flooding, or up to 0.5% chance of sea flooding. Lastly, Flood Zone 3 is defined as land with a likelihood of flooding of over 1% in any given year, making it a high-risk area.
How can I protect my property from flooding?
In the UK, flooding costs billions of pounds each year, impacting coastal areas such as Cornwall, West Sussex, and Peterborough, as well as places affected by rivers and surface water, such as Yorkshire, Lincolnshire, Merseyside, Cumbria and parts of Kent. The Environment Agency has moreover warned that flooding is expected to become more frequent and severe throughout the UK, due to climate change. To better understand the risk in your area, you can contact the Environment Agency to access a report on your property’s flooding history.
If your house is located in one of these at-risk zones, it’s important to take measures to make sure that if there is a flood, the damage will be as limited as possible. The main goal, however, is to try and make sure that flood water is not allowed into the property in the first place.
Planning permission for works in flood risk areas
One of the initial issues with refurbishing a property in a flood zone is obtaining permission to carry out the renovation work in the first place. Councils can be somewhat hesitant to grant planning permission for properties located in high-risk zones, since developments are likely to have an impact on the soil and existing drainage systems. If you are looking to carry out any renovation work that will require planning permission, you are likely to be required to carry out a flood risk assessment for your proposed works. The goal of this assessment is to evaluate the risk and how it will be managed and mitigated, even taking future changes due to climate change into account. It also aims to make sure that the development will not have a negative impact on flood risk elsewhere.
If you are looking to carry out renovation work in Flood Zone 2 or 3, you will need to have a land survey carried out, which will be another cost to include in your budget. This is to make sure that the development you are looking to carry out will not interfere with the soil drainage of the local area. The larger the area you are looking to develop over, the more difficult it is to be granted planning permission. If you are looking to develop in a Flood Zone 3, the land survey that you will be required to submit as part of the planning application will additionally need to be more detailed. These Flood Zones do not necessarily take into account all the rivers in an area and cannot be taken as a definitive guide to which areas are liable to flood and which are not. If you are looking to develop in a Flood Zone 1, you will only be required to submit a land survey as part of your planning application if your development is very large, which for a renovation or refurbishment project is unlikely to be the case. This does not include just flood risks from rivers only, it also includes lakes and the ocean.
Flooding Insurance
Another administrative consideration to bear in mind is the cost of flood insurance. While insurance can certainly be significant for vulnerable properties, it’s obviously well worth it to make sure restoration work and repairs are covered in the event of flood damage. You can have a surveyor complete a flood risk report or contact the Environment Agency for evidence to provide of your property’s flood risk. While some flood insurance is often included in your standard home insurance, if your home is at risk it’s especially important to be aware of exactly what is covered. For example, you may need additional contents insurance to cover the cost of damage to your belongings.
There is a new scheme entitled Flood Re, which is a joint venture between the British government and leading insurance providers, to make flood insurance more affordable, due to the increasing frequency and severity of flooding in the United Kingdom due to climate change. Laws are also beginning to move more in favour of the customer: you cannot have a claim denied because you did not supply a detail that the insurance company did not ask you for.
What to consider for a home refurbishment project
The primary consideration when refurbishing your house in a flood zone is to prevent water from entering the property in the event of flooding. The simplest way is to make sure the ground floor of the house is above the level that flood waters would be expected to rise to in a worst-case scenario. However, you may find it difficult to get planning permission, especially if the proposed floor level is significantly above that of the neighbouring houses. To get round this, you can have tanking installed: this is a waterproof band inserted into the wall which helps stop flood water penetrating into the rooms of the property. Doors and windows can be fitted with low-level, hinged flood barriers which can be quickly deployed in the event of rising water levels.
In addition to preparing your home to avoid water entering, another way to prevent damage is to make sure that you receive forewarning if the water levels are rising. One way is to install a sensor and alarm, that will give you time to move your important possessions to an upper level of the property. While the drawback with this system is that you would have to be in, it is better to have this warning than nothing at all. You can check upcoming flood risks via the Flood Information Service, and sign up to get flood warnings if you live in England, Scotland or Wales.
Design and building solutions in flood-prone areas
As potential water levels rise, it becomes more and more difficult to prevent water from ingressing, due to the increase in pressure. At this point the nature of the solution shifts from simple solutions to the more radical. One solution that you can opt for is to have the house built on stilts, or piles, to simply move it above the projected water levels. Nowadays, these stilts can even be of variable length, so that under normal circumstances the house is at ground level, but when there is a flood, the house floats up on them, and then descends again once the water levels have receded. This is not yet common in the UK, but is common in the Netherlands which experiences frequent flooding. Stilt houses can be a more expensive solution than others, but it also means that no matter how much rainfall there may happen to be, the interior of your house will not be flooded.
Depending on your location and how bad the flooding in your area tends to be, occasional flooding may be inevitable. You should therefore design the interior of the house so that any water that comes in does as little damage as possible, and that it can flow out of the house as easily as possible. The likelihood of flooding will also have an impact on your choice of materials and construction methods for the project. For example, you may wish to avoid using a lot of wood in the construction, since this will not stand up well to flood waters and could even end up rotting. Go for materials such as engineering bricks for your exterior cladding: they will stand up very well to water and have the added benefit of not being flammable. If the property has cavity walls, make sure that they have weep holes in them to drain out any water that may find its way in. The best material to choose for the floor is a ground-bearing concrete slab; this way water will not collect under the floor and you won’t need to install a pump to evacuate it. You may also opt for closed-cell floor insulation, which is not vulnerable to water damage.
Are you looking to renovate or refurbish a property in a flood zone? The right experts are key to successfully planning, designing and executing your project. Get in touch with an architect near you at find-my-architect.com to start bringing your renovation project to life!