Many people like the idea of a seaside home. But when looking for such a property, think twice about how it might be affected by flooding from the sea, or the damage that can be caused when heavy gales blow salt-spray and sand far inland.
While any form of flooding is bad news, flooding by the sea or any form of salt water is really bad news for buildings. Salt water can cause long-term damage to concrete and brickwork, and corrodes metal. It is particularly likely to cause serious damage to electrical systems.
Even when directly not exposed to flooding, damage and deterioration to property can still be caused by storms blowing salt spray, sand and even shingle inland.
Water in tidal rivers and estuaries is also saline, so flooding from these sources may cause salt damage.
Salt suspended in water is highly reactive chemically. It will quickly penetrate the usual materials used to construct homes, and holds on tight once it gets there. Salt is extremely corrosive, and corrosion is something you do not want happening to structural components of your home.
Salt causes serious damage to buildings
Salt water has seriously corrosive effects on concrete, including foundations, as well as bricks, mortar and plaster. Salt can penetrate concrete and slowly break it down, leading to weakness and instability that may emerge years later.
If a building is repeatedly exposed to salt water flooding, as can occur along the coastline of a storm-prone area, it can start to develop serious structural problems that could lead to collapse.
Salt will also corrode any metal used in buildings, such as cavity-wall ties and reinforcing bars.
Electrical equipment exposed to salt water will rapidly corrode. This might expose people to the risk of electrical shock. When a home has been flooded with salt or brackish water, the electrical systems need to be flushed with freshwater and then inspected to determine if any or all of the wiring needs to be replaced. That includes the wiring in the walls, the fuse box, and of course any appliances and electronic devices that may have been left in the home.
Wood may also become damaged by repeated exposure to salt water and spray. This is caused by ‘delignification’ where salt water penetration of wood leads to the formation of salt crystals on the surface and slowly pulls out lignin, part of the cell wall of the wood. Over time, this can cause structural damage as the salt eats into the wood.
What to do if a home is flooded by the sea
If a home has been flooded by salt water, professional advice should be obtained as quickly as possible. The best thing is to contact your insurers, who will be able to arrange help from an expert salvage company.
Affected areas of the building may need to be flushed with fresh water as soon as possible to wash the salt away. The building should then be thoroughly dried out using heaters and fans to remove moisture that might be embedded in walls and other structural components. Flood-damaged material should not be painted, plastered or otherwise covered until it is totally dry.
Like any flood damage, salt can also lead to the growth of mould in the long term if the damage is not handled appropriately. Mould loves moisture, and flooding penetrates hidden corners of a structure that can be very hard to dry.
It is particularly important to ensure that wall cavities are thoroughly dried out. Any insulation within a cavity wall will be ineffective if it is not completely dry, as water will conduct heat as well as encouraging the growth of mould.
Once dry, the house can be inspected to determine which, if any, repairs are needed to restore it.
Guarding against the risk of salt damage
Homeowners can take steps to prevent or at least reduce the risk of salt damage before it happens. Specially coated and treated materials are available for use in the construction of homes in areas susceptible to salt-water flooding. These can resist water penetration and make the chance of damage lower, as well as reducing the extent of damage when it does occur.
The use of suitable paints and other exterior finishes will also help reduce the need for frequent redecoration of homes near the sea.
It is important to check if a house is in an area at risk from flooding, and also to find out if a house has been affected by flooding in the past. Although much work has been done to improve flood defences along many parts of the coast, there are concerns that rising sea levels could result in such defences proving inadequate in the future.
It can be difficult to get insurance against flood damage on a home which has suffered from flooding previously, or is in a high-risk area. Even if cover can be obtained, insurers may well require very high premiums. Any problems with insurance will affect the value of a property, and this can lead to mortgage lenders not being willing to lend on the property.
It is therefore especially advisable to ask your building surveyor to make a full flood risk report when buying a seaside home, or one near a tidal river or estuary.