You can reduce the amount of water entering your property by using ‘flood boards’ on the outside of doors, window frames and air bricks.
Makeshift flood boards
The most basic method is to construct a strong wooden or metal barrier that is secured flat against the wall or frame surrounding a door or window. The pressure of floodwater itself will help seal the barrier. This can be enhanced by adding suitable material to make the seal between the wall and the board, for example a blanket or silicone type sealing compound.
The efficiency of makeshift flood boards will depend on the strength of the walls and the durability of the fixings used to secure the wood or metal panels used.
Purpose-made flood boards
Purpose-made flood boards for doors, windows, and air bricks will be more successful than sandbags for minimising floodwater entering a property. They are available commercially, but can be easily made by someone with DIY knowledge. In either case the product or materials will need to be purchased and installed in advance of a flood.
Do remember that in cases of very severe flooding (where floodwater is more than one metre deep) keeping water out of your property can do more harm than good. Unless your building is specifically designed to withstand such stresses, the hydrostatic pressures involved with deep water can cause long-term structural damage and undermine the foundations of the property.