Fitting buildings with means of sealing them, for example using bulkheads or shutters, makes it possible to keep the water outside the building. This applies not only to large openings, such as doors and windows, but also to the small openings such as perpends, ventilation grilles, conduits, letterboxes and the like. It is difficult to completely seal a building. Despite the measures and systems described here, water will almost certainly penetrate into the building, meaning that these measures will have to be combined with water-resistant materials.
In many situations, flood protection in a public area or outside the building will offer a stronger and more controllable measure. Mostly this will also be cheaper, since temporary flood protection around multiple buildings requires less effort than separate temporary protection for each individual building.
Buildings with functions that require few openings, such as underground parking garages, are easier to construct in such a way that they can be sealed off.