There are a variety of options and costs to doing so, from structural changes like reinforcing walls to resist water pressure and installing permanent pumps to remove water. (inc.com)
Will VAMS reinforce the walls of the egg - crate school? (vamboozled.com)
Tom Clancy's Rainbow Six Siege gives players unprecedented control over their ability to fortify their position by reinforcing walls and floors, using barbed wire and deployable shields, laying mines and more, or to breach the enemies» position using observation drones, setting charges, rappelling and more. (shortpause.com)