Sealed joint including water-absorptive, water-swelling coating at joint interface site for using leakage to repair leaks

A sealed joint, comprising:

• a first member;
• a second member;
• one of said first and second members having a portion fitted into a recess provided in the other of said first and second members;
• one of said first and second members on said portion and the other of said first and second members in said groove constituting a seal for normally sealing with the respective said other of said first and second members in said groove and said one of said first and second members on said portion for preventing infiltration of rain and washing water from one side of said sealed joint to an opposite side of said sealed joint;
• a layer of water-swelling material, which swells upon absorption of water to enhance sealing, being provided between said first and said second members at least partly within said groove, this layer being present in a sufficient quantity to re-establish a seal between said first and second members should said seal for normally sealing fail and leak water so that such water contacts said layer of water-swelling material and causes said layer to swell.